Thanksgiving Cool Down...Will it Really Happen or is it Model Fantasy?

GFS hints at big cold and possible storm last week of November. Is it possible, or will the cool down be less severe with less of a chance of a storm?

...stratosphere still warming...still looks like this could eventually downwell into an east based -NAO, and a -AO/-EPO. However, we'll see if this warming continues and if it eventually downwells into a 500mb block...



There are two possible issues here.

1. The development (or lack there of) of a Polar Vortex. The 12z GFS develops a big one, and displaces it due to a -NAO and HUGE +PNA into SE Canada causing by far the coldest air of the young winter...



Right now though there is no sign of a PV anywhere over the western hemisphere:



And, with an overall +NAO/+EPO/-PNA pattern persisting for at least the next 10 days I'm not sure if we'll see some sort of big storm occur that forms into a PV...right now the Euro has no signs of a PV at 240 hours, and still has a very +EPO/NAO, with a neutral-negative PNA:



And, while the ECM does have a S/W over the Plains at 240 hours, it isn't nearly as deep as the one the GFS has at 240 hours...this S/W gets pulled into the GFS's PV...there is also no sign of a deep PV over the N. Pole at 240 hours on the ECM, although it's there on the GFS:



So, big model differences at 10 days out...the GFS has a huge PV with a trough sitting over the Plains that eventually deepens as the PV becomes displaced...the GFS also has a developing +PNA at day 10 although it isn't too strong yet...the Euro is vastly different with the Pac pattern...so, getting to the Pac pattern, my next big concern:

2. The Pac jet will be ripping for at least the next 10 days. The GFS slows it down by day 16, but at day 10 the ECM shows no sign of weakening the +EPO and slowing the Pac jet down...the GFS ensemble members are different from the op in this matter as well, and do not slow down the pac jet that much either, and don't have a huge PV over SE Canada either...right now, there is some tropical forcing over the central and eastern equatorial Pacific. This may be strengthening the Hadley cell over the central/eastern Pacific and be the reason for the raging Pac jet right now...the EWP model shows this persisting for at least 10-15 days...



If this is the case the Pac jet will not slow down and allow for a huge Turkey day cool down like the GFS is showing...note that a lot of the ensemble members still show a strong Pac jet at the end of the run (FWIW at this point), and only like 2 or 3 other members (out of 11 pertributions that are different than the GFS) show a displaced PV making it into SE Canada:



The GFS (upper left) is the most negative with the NAO, most negative with the EPO, and by FAR the most positive with the +PNA...this should throw up a red flag that the cool down the GFS is continuing to show near the end of its run is very possibly complete fantasy...what may be happening is the GFS is seeing the stratospheric warming and down welling it too quickly.

So, despite the stratosphere warming there still are no guarantees of a big cool down. While the warming continues to strengthen, we don't know when the warming may downwell into high latitude blocks, and where they may occur. FWIW, the strongest warming does appear to be over western Canada/Alaska/N. Pacific. If the strong block ends up here, over Alaska/Aleutians, this could cause the cold to end up over the west/MW when the Pac jet does relax some, especially if the we don't get a Greenland block out of this. FWIW, there is some good stratospheric warming over like the Iceland/UK area, if we get a block there it may be an east based block. Again, no guarantee for cold over the east. If we get the best tropical forcing to be focused near the dateline as this warming downwells into high latitude blocking in 2-4 weeks, then we may indeed get a Greenland block to form. However, there is definitely no guarantee of that happening, and right now the pattern doesn't look good for cold, especially over the east as we end November and head into the beginning of December.

NOTE: TO ANYONE STILL VIEWING THIS BLOG

Since I see on the good ol' hit counter that a few people are still viewing this once and a while, I guess I should point you to my new site that I update more often:
http://ohweather.weebly.com/index.html
Hope to see you there

-Ohweather

Lake Effect Sunday-Sunday Night

Since lake effect can be so “fun” to predict, I am not going to try and summarize a multiple day lake effect event in one map. Instead, I am going to try to be as precise as possible for the 24-36 hour out range, so I am just going to issue a map for the next day. Here is the map for snow valid from 12z Sunday-12z Monday. It should be noted that the amounts shown are the amounts I expect to fall. In most cases the accumulations will be lighter.

A cold front will sweep through the area Sunday. It will come through the western Lakes Sunday Morning, the central lakes (Huron, Erie) Sunday afternoon, and the eastern Lakes (from Buffalo east) Sunday night. It will usher in much colder air, and will set off some lake effect. However, the air will not be all that cold behind the initial front. What could set off some major lake effect is a S/W that will rotate through 12-18 hours behind the front.

By late Sunday afternoon over the UP of Michigan/far NE Wisconson H850 will range from –2 to –6C. There will also be an upper low sitting to the NE of the area. This should be good enough to get lake effect rain/snow. During the day tomorrow I don’t foresee much accumulation across the UP, and the precip should be mixed, as air temps will still be in the mid-upper 30s. There could be some light accumulations across the higher elevations in the far NW corner of the UP, but other than that there shouldn’t be any accums. However, the winds will be whipping so it will be very nasty. Over the eastern UP the 850MB temps will likely be too warm, around –3C and there isn’t too much higher terrain, so the eastern UP will probably see mainly rain through tomorrow afternoon.

Sunday night surface temps will cool to the low-mid 30s across the UP, and 850MB temps will cool to the –5 to –10C range over the UP. This should change most of the precip over to snow over the western UP, especially over the higher terrain. The snow could be somewhat intense because there will be moderate lake induced instability, plenty of moisture in place, and a high inversion layer. The only limiting factor will be a somewhat limited fetch, but still several inches of snow is likely in the higher elevations of the western UP Sunday night, except for near the lakeshore. Farther east where 850MB temps will be a little warmer and there is less higher terrain the precip will probably remain mainly a rain/snow mix most of the night, but the precip should be pretty heavy so some slushy accumulations are possible, but nothing too significant.

Over the lower peninsula of Michigan the surface temps and upper level temps should remain a few degrees too warm for snow during the day Sunday, and there will be some subsidence behind the front. So tomorrow over the LP of Michigan don’t expect any snow, and only a few showers with the frontal passage.

Late Sunday evening though a S/W will start moving through the northern LP of Michigan, so by 6z Monday there should be some lake effect starting to set up over the northern LP (in and around Gaylord) behind the S/W. Precip type will still be an issue though as air temps will fall into the mid-upper 30s and 850s will only fall to around –5C, so a rain/snow mix seems likely. The fetch won’t be particularly long, but there will be moderate lake induced CAPE and there will be some decent moisture in place, along with a pretty high inversion layer so the precip will be somewhat intense. With that said, so areas inland from Lake Michigan over the northern LP could see some light slushy accums, but nothing significant.

Farther south in MI, the S/W probably will not get there until late Sunday night, but there could still be some light lake effect rain/snow before that, but again temps will be marginal. Later at night as the S/W comes through the precip will pick up in intensity as 850MB temps fall to around –6C, and there is increased moisture and lift as the S/W comes through. Temps will still be marginal, but this looks like one of those “snow when the precip is heavy and drizzle when it’s light” situations late Sunday night over southern Michigan. There could be some light slushy accumulations over southern Michigan as well where the heaviest precip falls, but again nothing to heavy.

Downwind of Lake Erie it won’t get cold enough for snow until late Sunday evening. However, by late Sunday night a southwest flow will develop with 850MB temps of –3 to –6, so western NY (including Buffalo) should get some pretty heavy lake effect precip Sunday night. However, temps really don’t look good for snows. Surface temps still in the mid-upper 30s and 850s only down to –4 or so over western NY, so I think most of the precip will be rain in the Buffalo area Sunday night. There will be some snow/grapple mixing with the rain in Buffalo metro, but nothing should stick. In the higher elevations just south of the city there could be some more snow mixing in, and maybe some slushy coatings, but it really looks like the heaviest precip could go north of there, more towards Buffalo, so even the hill tops south of Buffalo shouldn’t get much more than a couple inches, and lower elevations near Buffalo shouldn’t get much accumulation at all, at least through Sunday night.

Downwind of Lake Ontario it could barley get cold enough late Sunday night to get some snow mixing in with any precip in the higher elevations downwind of Lake Ontario (Tug Hill).

For areas south of the lake effect zones (Wisconsin, Illinois, Indiana, Ohio, northern PA) there could be some light mixed rain/snow Sunday night as the S/W mentioned above a few times comes through. No accumulations expected in these areas, however.

Note: S/W=shortwave, which is basically just a weak cold front.

Note: I don't expect much snow downwind of Lake Superior in Canada through Sunday night as temps will remain too warm.

The Lake effect won't stop on Monday though. It will continue through Wednesday. I will make forecasts for it one day at a time like I have done for Sunday.

New Post Coming Fairly Soon

I know I haven't posted since Saturday, but I am usually pretty busy. The forecast I posted Saturday so far looks like it's going to verify halfway decently so I see no reason to sneak in an update, and there really aren't any major storms over the next couple days that need our attention, I'm not going to post because I don't have too much free time to work with...but on Friday (late in the day) I will have another detailed extended forecast.

So...Last Night I Laid out Where the Troughs and Ridges Would Be

Here are the regions the forecast discusion below covers...look for your region below...regions are bolded.

So now I am going to lay out what those troughs and ridges will do to the weather each part of the country will be seeing:
NW: Remaining dry and warming up through Wednesday. Then by Thursday, as everything starts shifting east you should start seeing some cooler and wetter weather from the trough that will be building over the NW. Cool and unsettled conditions should last through next weekend.
SW: What fall? Should remain warm and dry. Next weekend however as the trough really digs off the NW coast there could be enough moisture for some rain across northern California and Nevada.
Upper Midwest: There currently is a front moving through eastern MN/IA and into WI. That is bringing some showers/thunderstorms to that area today, and will continue to this afternoon, before clearing out and cooling off tonight...the rest of the Upper Midwest should remain dry with near normal temps today and tonight, but tomorrow a cold front will start pushing through. Expect some showers with the front but nothing too heavy. Behind the front it should dry out but will be much cooler, 10-15 (50s for highs) degrees below normal. There will likely some frosts/freezes over the Midwest Tuesday morning, especially over northern Minnesota. Tuesday will remain cool and dry but Wednesday another S/W will rotate around the cut-off low over Canada, so on Wednesday expect some clouds and maybe a few sprinkles, along with some breezy conditions. Then Wednesday night after the S/W comes through the bottom falls out and much of the upper Midwest sees frosts/freezes. Thursday will be dry but cool...Thursday night the winds will be even light than Wednesday night so we will be able to radiotionally cool down better Thursday night, so widespread HARD FREEZES are very possible Friday morning...but on Friday temps should rebound back into the 50s and will be dry, but again Friday night/Saturday morning there could be widespread freezes over the upper Midwest. By Sunday, the trough over the east will begin lifting out so temps should start to moderate. But, the trough and cool weather will take the Canadian high pressure with it, so the chances for precip will increase by next Sunday over the upper Midwest.
Southern Planes/Texas: The northern portions of this region (Missouri, Nebraska, Kansas) will see some showers and a cool down as the front moves through and a trough sets up over the east. But, the ridge over the west should prevent an extreme cool down, so frosts/freezes are unlikely anywhere in this region. Farther south over Oklahoma, Texas, Arkansas, and Louisiana the ridge over the west should extend into these areas, so they will remain dry and warm through the next week.
Great Lakes: The northern Lakes will be impacted by a cold front today, which will usher in some cooler air (highs in the 60s) and may cause a few showers/storms over northern MI/WI today/tonight as it passes, but nothing huge. The southern lakes should remain seasonable and dry today and Sunday, except for eastern OH, PA, and NY where an upper low over the east should cause some showers, heaviest over NY and central PA where over .5" may fall. Then on Monday things remain interesting, as a strong cold front approaches the western Lakes. On Monday western MI and WI should see scattered showers/storms as the front comes through, and Monday night those areas will cool into the 40s, and the northern/western Lakes could start seeing some Lake effect rain setting up. The rest of the lakes Monday will be dry and seasonable. But, on Tuesday the front will clear the rest of the lakes. Again, a few showers/storms and breezy conditions will be associated with the front, but moisture and instability will be limited so they won't get out of control. So, on Tuesday MI will be seeing clouds/showers and cool conditions (highs in the upper 50s/lower 60s) as some lake effect continues through the day. The eastern Lakes region (OH, PA, NY) will see scattered storms, with temps being slightly above normal in western NY/PA as the front won't come through until later, and near to below normal in Ohio as they will see a morning frontal passage. Tuesday night there may be some light lake effect rain here and there, but nothing widespread as the air mass will be drying out some...temps in the 40s Tuesday night. Wednesday a shortwave (S/W) will start coming through the northern Lakes, giving those areas a very cool day with breezy, cloudy conditions and maybe some showers. Highs over the UP of Michigan may struggle to get to 50 Wednesday. The rest of the lakes (southern MI, OH, PA, NY) will be partly sunny with breezy conditions, and with highs in the lower 60s. But, by Thursday the S/W will reinforce the cold over all the lakes...so on Thursday expect mostly cloudy skies with showers over all of the lakes...expect highs in the mid-upper 40s over northern MI, lower-mid 50s over southern MI/northern NY, and mid-upper 50s over PA/OH. Now...as for frozen precip it could be cool enough for some sleet/snow to mix in over the UP of MI Thursday morning...surface temps will be in the upper 30s so nothing will stick...Thursday night the heart of the cold air will be in place...so...the UP of Michigan will likely see some snow showers Thursday night. Temps again will be in the mid-upper 30s so little if any snow will stick...even the northern portions of the southern peninsula of Michigan could see some snow/sleet mix in Thursday night, as well as areas downwind of Lake Huron over western Canada. Now, in southern MI, northern OH/NW PA, and western NY it should be warm enough for any precip to fall as rain. But, inland areas that won't see lake effect showers/clouds (SW Michigan, inland areas of northern Ohio, northern Indiana) could clear out enough to see frosts/freezes...so in the lakes Thursday night it will be a tale of lake effect rain (or snow) or frost/freezes. Friday with such cold air aloft all of the region will see instability showers popping up, with maybe a little snow mixed in over northern MI. Highs in the 50s. Saturday the lakes will start to moderate, but there could again be some light lake effect rain/snow over the northern Lakes Saturday morning, maybe a few sprinkles over the southern Lakes, and areas that don't see precip will again see frosts/freezes Saturday morning in the Great Lakes. Saturday highs will start rebounding, 50s and maybe lower 60s over the southern Lakes. Sunday should be a nice day. Any lake effect should be gone with highs in the 50s/60s.
Ohio Valley: Should remain fairly dry and seasonable through Sunday. The eastern portions of the OV however will see some rain this weekend from the upper low over the east. A cold front will sweep through Tuesday, bringing a slight chance of rain and a cool down. Wednesday will be dry but chilly, except for the mountains in WV/PA, where the mountains could ring out some moisture coming off the lakes and produce a few showers. Thursday will be more of the same. Chilly and mainly dry with highs in the 60s. Friday and Saturday morning there will be some frost over a lot of the region, with widespread frosts/freezes over central OH/IN. Otherwise things will remain dry and a little cool through the weekend.
Southeast: The SE is currently a little rainy and chilly, this should continue through the weekend (Sunday will be a little better but still not great). Monday-Tuesday should be dry/warm. The front will also sweep through the SE on Wednesday. Maybe an isolated shower/storm but nothing extreme or too severe. The end of the week and into the weekend will be a little cool, but still pleasant with highs ranging from the 60s in TN to the 70s over much of the region, and still some 80s over southern AL/GA/FL. Things should remain dry but cool over the weekend.
Northeast/Mid Atlantic: Will remain damp through the weekend, with highs in the 60s/70s. By Monday things should dry out and the region will see highs ranging from the lower 60s over northern Maine to the mid 70s near DC, with upper 60s and lower 70s in between. More of the same Tuesday. But, Tuesday night a front will sweep through the region. Expect a few showers along the front, but nothing widespread. By Wednesday temps will be much cooler, upper 50s over New England and to the west in the GLs, and lower-mid 60s in the I-95 corridor. Things should be pretty dry. On Thursday a S/W will reinforce the cooler air, so much of the region will be in the mid-upper 50s, with some 60s trying to hang on near the coast. Friday morning there will be widespread frosts/freezes in the interior regions of the NE. Friday will again be dry but cool, highs in the 50s/60s. More of the same through the weekend. Should be fairly dry but cool with highs in the 50s/60s during the day and lows in the 30s/40s at night with a lot of frost inland.

Weather Discussion Through Next Week

NOTE: SINCE BLOGGER SUCKS, THE IMAGES AREN'T SHOWING UP IN THE POST...SO YOU WILL HAVE TO CLICK ON LINKS...SORRY FOR THE INCONVINIENCE...(I removed the vulger language that once was here)...

Discussion Through Next Week

BEFORE READING: I WILL WARN YOU, THIS DISCUSSION IS VERY IN DEPTH AND MAY BE A LITTLE CONFUSING TO SOME, WHICH IS OK! IF SOMETHING CONFUSES YOU, READ MY NOTE AT THE END OF THE POST!

Large Scale Pattern:

Global Water Vapor With Stuff Drawn On It

Currently the water vapor is LIT UP with several key features that will determine the large scale pattern for this up coming week…lets look at them and see what they are expected to do:
-Upper low over eastern US. This will slowly start weakening and moving off to the NE over the next couple days as the S/W over the north central US picks it up. It will leave enough of a trough over the eastern US to allow the upper low and associated front to move through much of the Midwest/NE early next week, and really cool things off.
-The upper low to the SW of Alaska and over the Sea of Japan are going to be very important, as they are going to cause the two ridges over the Pacific to amplify. The one over the NW Pacific will continue to drift NE over the next couple days. It will take the northern branch with it, causing the ridge over the western Pacific to grow northward. The ridge building will cause the upper low to the NE of the ridge (SW of Alaska) to drift more to the south, causing a trough over the central Pacific. The upper low drifting south will amplify the ridge over the East Pac/western US, and it will be oriented more N-S. This will cause the northern Branch to blast into Canada moving SSW-NNE, so it will be tapping the Arctic air. The amplification of the ridge over the eastern Pac will coincide well with the AO and NAO going negative. This will cause the northern branch, which is moving well north into Canada and tapping arctic air to dive back to the south over the eastern US, causing a trough over the east.
-Described above is an amplified pattern…it will consist of a ridge over the western Pacific, trough over the central Pacific, ridge over east Pac and western US, a trough diving into eastern US, and the westerlies south over much of the Atlantic basin, which will impact tropical activity, which I will get to later.
-Now, this pattern will take a couple days to fully develop…but by Sunday night it should pretty much in place, and the upper low/cold front currently off the Pac NW coast will start moving through the northern US and bringing the coldest air mass of the season with it…
Here is what the set up will look like by Monday:

What the pattern will look like on Monday

Things will be starting to amplify more over North America. And, as you can see an upper low and trailing cold front will begin dropping down into the northern US, and will bring a pattern change. Now, you may be wondering: How come the S/W currently moving through the northern US isn’t going to cause a large trough in the east and cause a pattern shift?

500MB analysis for Friday evening at 9PM EDT

Well, currently the pattern is a little more zonal. So, the S/W is moving more W-E than anything. Also, the upper low over the SE US is currently amplifying the ridging over the western Atlantic/NE US, which is causing the jet to move north back into Canada. So, this S/W is just going to give the NE US a glancing blow.

As mentioned above, over the next couple days what will happen is the upper low over the east will weaken and move east some, causing the ridging over the Atlantic move more to the east. Also, the pattern over the Pacific will be amplifying. So, we will get the northern branch diving down towards the NE US a little bit, instead of being deflected more to the north, so the S/W will move farther south than the current one. Also, the S/W will be stronger than the one currently moving just north of the US…

Before we move any farther, lets time the front that the S/W will drag through early next week and discuss its impacts:
Timing the cool down:

Timing the front

Here is the timing of the front…here is what to expect with the frontal passage:
-Some clouds and showers. The front will be strong and will add lift, but there will be some ridging ahead of the front limiting moisture return.
-Some gusty winds. It is a strong front, so winds could gust as it comes through.
Here is what to expect after the front passes through:
-Temps 5-15 degrees below normal.
-Some frost in interior portions of the NE, the GLs, and Midwest.
-Partly cloudy skies. Cool air aloft will cause some instability but little moisture behind the front. Maybe some lake effect rain showers, but nothing extreme.

As we get towards Tuesday and Wednesday, the upper low that will drag the front through will likely run into the –NAO block, stall out, become negatively tilted, and strengthen into a large cut-off upper low over Hudson Bay. This will cause the trough over the east to really deepen, and will also cause weak S/Ws to rotate down through the GLs, which will bring continually cooler air and will cause an increase in lake effect rain, and maybe some mixed precip over the northern lakes. (we’ll cross that bridge when we get there). But, all you need to know is that if you live in the NE, expect cool and unsettled weather from when the front goes through Tuesday/Tuesday night into the weekend. But, by the week of the fifth the cut off over Hudson bay will finally start to shift east…as the pattern continues to change…let me briefly touch on what the pattern will do Tuesday-next weekend:

On Tuesday we will still have the same setup…ridge in western Pac, trough in the middle, ridge in the eastern Pac/western US, trough developing in the east, and some ridging over the Atlantic. But, now we need to think back to the huge upper low currently over the Sea of Japan. Currently it is amplifying the ridge over the western Pacific as it slowly moves around the ridge. By Monday and into Tuesday, that upper low will be working around the northern side of the ridge. As that happens, it will cause the ridge to flatten and spread east some. This will nudge the upper low/trough over the central Pacific east, which will shove the ridge over the western US east, and by the weekend will start pushing the trough over the east to the east. By the end of next weekend, the trough that originally will be in the central Pacific will be over the western US, and the ridge that will be building over the western US will start pushing east, although with a –NAO the trough over the east will be stubborn to get out, so the ridge will start getting flattened by the trough over the east, which will slowly start moving out next weekend…this is where I will leave off…the end of next weekend…and pick it up from there tomorrow…

Now, earlier I mentioned I would get to tropics…right now, there is Kyle. Kyle is a strong TS, and may become a minimal hurricane. It may clip SE New England and will be going into Nova Scotia. There is also a tropical wave in the Atlantic, which the NHC is giving a 20%> of developing over the next 48 hours…currently it is lacking heavy thunderstorm activity, and is being impacted by shear, that won’t be going away for a few more days. So, this system likely won’t become anything significant over the weekend. If it does happen to develop, currently the ridge over the Atlantic is strong, so the wave should continue moving to the WNW for the next few days. But, later next week as the trough digs over the eastern US, if there is anything left of this system the trough should wisp it out to sea…

NOW, I UNDERSTAND HOW SOME OF YOU MAY BE A BIT CONFUSED, AS THERE WAS A LOT OF STUFF IN THAT POST AND SOME OF IT WAS A LITTLE COMPLICATED. SO, IF YOU ARE CONFUSED, PLEASE, LEAVE A COMMENT BELOW THE POST. IF I GET ANY COMMENTS I WILL PROBABLY MAKE AN EDUCATIONAL POST AT SOME POINT TOMORROW OR SUNDAY, SO WE ALL CAN LEARN. IF YOU ARE CONFUSED, LEAVE A FRICKIN COMMENT ABOUT WHAT YOU ARE CONFUSED ON! THAT IS WHY THERE IS A PLACE TO LEAVE COMMENTS BELOW EACH POST!

Hello folks! Welcome to my Blog! A new Winter is Closing on us!

During the summer I really got lazy and didn't post on here all that often...mainly because I was pissed because the format for pictures in a blog post infuriates me...anyway...I am going to start posting here much more often...now...this year I am not going to have a lot of free time...a lot of homework every night...but I should still be able to post whenever things get interesting weather wise...here are some new things I will be trying this year:
-3 to 7 day discussions, to discuss the pattern in the medium range and possible upcoming storms.
-7 to 14 day discussions, to discuss the longer range pattern, and maybe hype up a storm...maybe...
-Also, I want YOU to get involved...a lot of us who read the blog are weather enthusiasts who are still learning...which is GREAT! It's awesome that you guys want to learn more...so...if you have a question...about anything...please utilize the "comment" button below each post and ask a question if you have it...I will be more than happy to answer any questions...

So, check back often, ask questions, and enjoy reading! I will likely have my first post with real substance Friday...

Tropics Heating Up! Three Areas of Concern

Sorry for the inconvenience, but blogger fucken sucks with the way you uploaded images can only be before the text...so I tried using a site to host them so I could put them where ever I wanted...but they show up as x's...so I'll post a link below each pic to where they're being hosted...sorry for this...

We have three “invests” in the Atlantic this evening, all of which may develop. Lets first focus on Invest 90L, out on the eastern Atlantic:

http://img523.imageshack.us/my.php?image=invest90dr5.jpg
Currently there appears to be a weak swirl just to the east of the heaviest convection. So, this system is not terribly well organized but if convection continues to fire as it is now the circulation will organize more and further intensification will occur. But, is the environment favorable for this?

http://img523.imageshack.us/my.php?image=eastatlanticshearsl9.png
http://cimss.ssec.wisc.edu/tropic/real-time/europe/winds/wm7shr.GIF
Currently, shear is fairly low over the system, 10-15 knots. This will not accelerate development but it is low enough to allow further slow development, if other factors contribute:

http://img515.imageshack.us/my.php?image=sstspp7.png
Currently, it is over marginal SSTs for development, 27-28 degrees Celsius…again…this will not cause rapid development but will not prevent it from slowly occurring if other factors fall in place.

http://img127.imageshack.us/my.php?image=saldd2.png
http://cimss.ssec.wisc.edu/tropic/real-time/wavetrak/winds/m8split.html
As you can see, Invest 90L is riding just out ahead of a very strong burst of the SAL (Saharan Air Layer). This, will also prohibit rapid development, however, this system is moving quite quickly so may stay just ahead of the SAL. So, right now all factors are marginal development, so I am calling for slow development. I believe this system may become a depression as early as Sunday and probably will by Monday.
As for where this thing will go, there is a strong subtropical ridge to the north of it. This will steer it to the WNW over the next few days. Once it gets near the Bahamas by Thursday, it will start approaching a large weakness in the ridge due to a large trough over eastern North America. This should allow this system to curve out to sea, perhaps near Bermuda but away from the US, if it does develop. More on future strength:
Down the road, it appears that this invest may encounter higher shear due to a band of sub tropical jet stream energy on the southern side of a large ridge, perhaps again slowing any development.

http://img127.imageshack.us/my.php?image=futurelowlevelsteeringstn9.png
As you can see on the above image from the GFS (which doesn’t even have the system at this point) that the flow will be very brisk from the ESE at the mid levels near where the system will be around this time. This could very well tear the system apart. Right now, the few models that have run on this are showing a strong TS/weak Hurricane by Thursday. Right now, I do not know that this will come to fruition. I am calling for slow development to a weak tropical cyclone (TD/weak TS) through Tuesday, but then a halting of development and perhaps a weakening thereafter through at least Friday. To be honest, I do not know if this will be around next weekend. So, to me this is a watch and see just incase but don’t expect anything big system.

The next invest on our list is Invest 91L in the northern Gulf of Mexico. This one is much closer to home and bears watching:

http://img127.imageshack.us/my.php?image=invest91pb1.jpg
Over the last few hours, a weak spin has been evident on the visible satellite, near or possibly under the deep convection. This system is not what I would call on the verge of becoming a depression, but is over a fairly good environment for strengthening and already has deep convection and some kind of at least mid level, if not low level circulation.

http://img515.imageshack.us/my.php?image=westatlanticshearyg5.png
http://cimss.ssec.wisc.edu/tropic/real-time/atlantic/winds/wg8shr.GIF
As shown above, this system (which is associated with an old frontal boundary) is under low shear, 5-10 knots. This is favorable for development. However, it should be noted that there is an upper low near Cuba. This is causing higher shear to the southern portion of the system and may restrict outflow to the S-SE quadrants of the system.

http://img515.imageshack.us/my.php?image=sstspp7.png
Invest 91L is also over warm waters, 28-29 degrees Celsius. This is also favorable for development. There are a couple of inhibiting factors though, both of which can be seen on water vapor imagery:

http://img515.imageshack.us/my.php?image=gomwvxu2.png
The upper low mentioned above is causing some shear on the southeastern quadrant of the system. This may slow development some. This upper low may also limit outflow for the rest of the weekend. But, the upper low should get out of the way by Monday. There is also some very dry air to the north of the system. This is also limiting outflow to the northern quadrant of the system. This will likely not go away at all over the next few days. So, the environment is marginal for development currently, but will become more favorable by Monday, but some dry air may still be a problem over the coarse of this systems lifespan. So, I believe slow organization will continue through Sunday, perhaps into a depression as early as Sunday evening. After Sunday, there is no reason why slow to perhaps moderate intensification won’t occur until Tuesday, when this system will run into Texas. So, I expect a moderate tropical storm (perhaps as strong as 50-55 knots) by the time this hit Texas on Tuesday. As for where exactly it will go, there is a decent ridge to the NW of this invest. This ridge will slide east over the next couple days. This should steer Invest 91L to the SW in the short term, then to the west late Sunday through Monday, and then as the ridge becomes farther east of the system by Tuesday, a turn more to the NW seems logical. This would put landfall somewhere between Corpus Christi and Houston Tuesday afternoon. I will have a full projected path once this thing is named.

http://img515.imageshack.us/my.php?image=invest99bz1.png
As for Invest 99L (above) it has a well-defined LLC, but there is no deep convection, because this thing is encountering very dry air and increasing shear. No development is expected as this system continues to the WNW over the few days.

August Outlooks

Note: These are my first attempt at long range forecasting. They are highly experimental, and I am trying these to see if I have any skill in long range forecasting, and if I will be making these maps monthly.
Discussion:
During the month of August, it appears that there will be a large ridge over the western US, and an occasional trough trying to dip down over the GLs/NE. It appears that from time to time, the ridge in the west may try to build east for a couple days, but nothing persistent. In the west, there will be a dry SW flow on the west side of the ridge. I have put the coast in slightly lower temps than the rest of the west due to the cooling effects of the Pacific. However, in the rest of the west, under the ridge and with a SW flow, it looks like it will be warm and fairly dry. So, I put much of the inter mountain west in above normal and fairly dry conditions. In the extreme NW, a trough may be trying to build down, so I added normal precip and near normal temps. In parts of the SW, I did not go crazy with temps and added in normal (may end up busting a little above) precip, due to the monsoonal flow. Now, you may be wondering why there is a large area of below normal on the edge of the heat ridge and well above normal precip. Well, it looks like it will be quite stormy on the northern edge of the ridge, as it usually is. Which is why I put in below normal temps and above normal precip in that area. The above normal precip I have fairly high confidence in. However, I am a little concerned that the temps may end up being closer to average instead of below average in that area, due to warmer night time minimums, even if day time maximums are below normal. In the south central states, I put in above normal temps and below normal precip. The flow around the high the majority of the time will be out of the NW, which is a fairly dry flow, so I expect fairly dry conditions in that area with above normal temps. In the NE, I added above normal precip and put in above normal temps for most of the NE, but with a small area of cooler weather noted closer to the Canadian border. This is because a trough will be effecting the area from time to time, which easily agrees with the above normal precip. However, why did I put in above normal temps? A few reasons...one of the big reasons is despite the troughiness for the majority of the summer, temps have been normal to above normal in the NE, mainly due to nighttime lows being warm. Although I really have no reason to explain it, this reason made me lean against below normal temps. Another reason is, the heat ridge may try to build east from time to time, causing above normal temps as that happens. The third reason...which may just by me going out on a limb...the models are hinting that the trough axis may try to setup a little farther west...over Ontario/the northern GLs...opposed to Quebec...this would put the NE US in a warm, moist SE flow ahead of the trough. So, on a perhaps slightly shaky decision, I went with above normal in much of the NE/Mid Atlantic for these reasons. NOTE: I CAN SEE HOW THIS CAN LEAD TO A BOUT OF MAJOR HEAT IN THE EAST. And in the SE I went with above normal temps and normal precip because the ridge will extend east into the SE.

Dolly Update: Dolly Still Threat to Western Gulf

Note: 12z=8AM EDT...0z=8PM EDT
Discussion:
Dolly's interaction with the Yucatan, although brief really disrupted the circulation last night, so Dolly has spent all of today trying to develop an inner core, so it really hasn't strengthened yet. However, it looks like a small inner core has formed, and now an "eyewall" is trying to form, although up to this point it isn't very pretty yet. The reason the system is having a tough time wrapping deep convection all the way around the center is because of dry air off to the SE of the COC. However, it appears that Dolly will be moving away from the dry air, which should help convection wrap all the way around the center. Right now, outflow is good in all quadrants except the S/SE quadrant, where some dry air is getting pulled into the system. Also, wind shear is very low and is expected to remain that way. Also, oceanic heat content is moderately favorable for intensification in Dolly's path over the next day. So, over the next day, once Dolly can wrap that "eyewall" all the way around the center, I see no reason while a modest to fairly quick strengthening won't occur. After that, all factors will remain favorable for intensification, except for oceanic heat content which will become a little less favorable for intensification. It will not cause a weakening in Dolly, but will slow strengthening. This little "cooler eddy" of water as described by the NHC may save the western Gulf coast from a major hurricane, but again with modest to good conditions for strengthening over the next 36 hours while it is over water, I believe a CAT 1 hurricane will easily be reached, if not a CAT 2. (less bullish than yesterday, due to inner core taking longer to get organized) Now that you know the reasoning for the intensity forecast, here is the reasoning for the track:
The reasoning for track is similar to yesterday, but with a more westerly movement than expected today, the track has been shifted slightly to the left. Currently, a ridge is keeping Dolly on more of a westerly track rather than a NWerly track. However, this ridge is expected to break down over the next day and allow Dolly to move more WNW. The ridge breaking down will also cause Dolly to slow down some over the next day. However on Wednesday as Dolly approaches landfall, a ridge will start building to the north of Dolly. This will nudge Dolly more to the west again just before landfall. Right now, this solution is supported greatly by all models, as there is a very tight model consensus for both track and speed. Landfall looks to be very near the TX/MX border. This could pose a threat to the Brownsville area which is fairly heavily populated.
Forecast intensities:
12z Tue: 55 knots
0z Wed: 65 knots
12z Wed: 80 knots
0z Thu: 50 knots
Landfall intensity: 85 knots (~97MPH)
Not as bullish as yesterday, due to the Yucatan disrupting the circulation more than expected (not surprising, given that it was a developing cyclone), but you can't blame me for being a little bullish at first, because all the factors were/are there for intensification, but the center took a while after getting back out over water to organize. Still, far southern TX/northern MX need to prepare for a storm surge of 4-7', power outages, and perhaps some structural damage, especially to mobile homes.
NOTE: Some of the links are time sensitive, and I wrote this around midnight. I believe the NHC link, dry air link, shear link, and model link are all time sensitive, so they may not look exactly the way they did when I wrote this discussion.

HURRICANE ALERT: DOLLY POSES MAJOR THREAT TO WEST GULF COAST

Right now, all other weather issues will have to be put to side, because this will probably dwarf all of them. All things are pointing to a strong hurricane moving through the western Gulf and into the southern Texas coast. This storm will make Cristobal look like a puff of wind and a squirt of rain. Based on radar and satellite imagery, it is clear that Dolly's center has relocated to just WSW of Cancun. Also based on radar and satellite imagery, it is over the southern area of deep convection, and is rapidly organizing. Also, with the re-location, the center will just graze the Yucatan, so strengthening will not be inhibited at all until landfall on Wednesday.
Full discussion/reasoning:
With the relocation of Dolly, I went north of 0z guidance. But, over the next 48 hours, Dolly will follow the flow around a high pressure over the southern US/northern Gulf. It appears the ridge will be braking down some to the N of Dolly, so Dolly will continue moving in a similar WNW direction over the next 48 hours. But, with the ridge weakening some Tuesday, the forward motion of Dolly should slow some. On Wednesday, the ridge may try to build back a little bit north of Dolly, and with Dolly being farther north than originally progged, it looks like the ridge may cause Dolly to move a little more the the south on Wednesday. However, no matter how you look at it, landfall will occur in either extreme northern Mexico, or south/central Texas. As for intensity, the ULL that is currently causing some shear to Dolly is expected to get out of the way quickly here, and may actually help the outflow which is already very good. Also, Dolly will be moving over warm Gulf waters. In summary, Dolly has and will continue to be in an environment that features good outflow, low shear, and warm SSTs so I see no reason while a fairly rapid strengthening trend will not occur until this thing hits land. Hopefully, this thing will not explode like several hurricanes have over the last few years.
Intensity forecast (could change, bottom line is this will bring major impacts to where it makes landfall):
0z Tue: 65-70
0z Wed: 85-90
0z Thu: 105-110 (near landfall).
Just a note, the area between Brownsville and Corpus Christi are pretty sparsely populated, and that is where the current track has this going. However, a slight deviation in track (which could very well occur) would bring this thing into more populated areas. In summary, everyone from northern Mexico to central Texas need to start preparing now for a hurricane making landfall. A large area of heavy rain and damaging winds accompany hurricanes, and destructive storm surges can also occur, and extend well away from the center, so do not focus on where the center will make landfall because the effects of hurricanes are felt over large areas.

Cristobal Forms; Impacts to Carolinas, and Possibly Cape Cod

(Click on images to see full size)

(To avoid confusion, the Outer Banks are in the "low impacts" zone, and the shoreline of mainland NC is in the "minimal impacts" zone)

(18z=2PM EDT)

Well, the area of low pressure that was in the Gulf earlier in the week has played a trick on us. Instead of drifting through the SE US, and giving them some much needed rain, it tracked across Florida, and has since fed off the warm Gulf Stream, and has been named a tropical storm. Forecast Discussion:

Over the next day, Cristobal will continue to follow the very weak steering currents around the periphery of a high. So, a slow NE motion will continue. After that, an approaching trough will break down the high, so Cristobal will not be forced towards the coast. The trough will be bringing in a nice blast of westerlies, so an increase in foreword speed is expected. Ahead of the trough, steering currents will still be out of the SW, so as I said a NE motion is expected to continue. By Tuesday, the trough will catch up to Cristobal. This will cause a further increase in the continued NE motion, and will also cause Cristobal to become extra tropical. As for intensity, low shear and warm SSTs should allow for a little more strengthening over the next day or so. However, I do not expect a rapid increase in intensity, especially over the next 24 hours due to the center being exposed, and proximity to land. After that, the storm will move over cooler SSTs and shear will increase in association with the trough, so a weakening storm and an extra tropical transition will begin by late Monday. Intensity forecast:

18z Sunday: 50-55MPH

18z Monday: 60-65MPH

18z Tuesday: 45-50MPH

Other tropical notes: Bertha has again become a hurricane over the far northern Atlantic, but is soon to become extra tropical. It is by far the longest lived July storm on record (17 days and counting). The tropical wave in the Caribbean (Invest 94L) has not developed over the last few days, and is still just an open wave with no center of circulation. However, it is in a favorable environment for development, and may develop over the next few days as it moves over the Western Caribbean. This system is expected to effect the Yucatan Peninsula, and then the Western Gulf Coast, so all interests in those areas need to keep tabs on this system.

NOTE: This new layout which I am digging has one side affect. The warning box, blog archive and other weather links (recently added to tropical links) are all at the bottem of the page.

Invest 94 Really Starting to Disappoint; Development in Gulf of Mexico?

The tropical wave in the central Atlantic that looked like it would develop a couple days ago has really looked not impressive since then. Today there have been some intermittent bursts of convection, but nothing really organized. And it appears that the low level circulation has weakened. The reason for this is some shear and the system moving through some drier air. These limitations are not killing the system completely but are preventing it from developing. Over the next few days the environment will be similar, so now I am backing off my earlier prediction of this thing developing, and am giving this thing a 50/50 chance of becoming a depression by Friday. After that, I am not going to speculate much more, but what's left of it, or potentially a developing storm will keep moving through the Caribbean. Down the road the environment may become more favorable for possible development, so this system still needs to be monitored. No matter what the Lesser Antilles will see heavy rains and gusty winds. In summary: Lesser Antilles, expect some gusty weather. Even if this system doesn't develop in the short term, it is a potent tropical wave and needs to be watched down the road in case it runs into a more favorable environment.

GULF SYSTEM: A weak low pressure has developed off of Florida's gulf coast. No imminent development is expecting, but it is in a low shear environment and is over very warm waters, so if convection can keep firing near this thing it may slowly organized. Right now, steering currents are very weak. But, with that strong, building high to the east of this system, I think this thing will slowly more to the north over the next couple days. With its proximity to the coast, and right now the lack of a a nice spin, I don't think this will turn into too much. Now, there is an outside chance at development. This thing will either move more north to NNE and go into the FL peninsula. This would not permit development, but would bring more rain to Florida. Or, the high will build faster, and the low will move more north to NNW, and hit in the Florida panhandle. This may allow some organization into perhaps a TD or weak storm, due to low shear and warm SSTs. There is a slight chance if this staying over water long enough to become a named storm, but either way this thing will bring some much needed rain to FL and the SE. After landfall over Florida, the strong ridge to the north of this will cause it to meander around over the SE the rest of the week, enhancing precipitation some. Later this weekend, as a front approaches and weakens the ridge, any residual moisture from this may enhance precip some over the NE/Mid Atlantic.

Bermuda Gets Pounded!

http://www.youtube.com/watch?v=yHjf3HrBikw

Bernuda has been getting pounded today by Bertha, with winds close to hurricane force, high seas and heavy rains. This will continue this evening. Today, as Bertha finally got going and moved out of the cooler pocket of water she created due to upwelling, strengthened, and will likely be upgraded to a hurricane at the 5PM advisory. The above Youtube video is from earlier today showing tropical storm conditions on Bermuda.

Invest 94 Update: Not as Impressive as Last Night, But Development Still Expected

This afternoon of visible imagery there was a well defined center. However, it is just south of that northern curved band. To be honest, this thing is not looking organized right now. However, I still think it is on the verge of becoming a depression, so it is only a matter of time before we get a burst of convection over the center which would likely prompt an upgrade to depression. Now, where it goes from here and how strong it gets are still in question. The models are a little farther south than yesterday, and some of them are no longer showing this developing. Based on the rather poor satellite presentation, I am not expecting as quick of a development as I hinted at yesterday. But this thing is in a favorable environment for development and already has a low level circulation, so I still think that we will see a depression form by sometime Tuesday, a storm by sometime Wednesday, and possibly a hurricane by the weekend. Based on the above, all of the Lesser Antilles, Puerto Rico, and Hispaniola need to monitor this. Where it goes after this week is still highly uncertain, and how strong it gets is also uncertain.

Invest 94 Named in Atlantic: Big Time Development Possible

On Sunday Invest 94L was named in the central Atlantic. This evening, there has been a flair up of convection that has a clear cyclonic swirl. As of right now (around midnight) I believe this is already on the verge of becoming a depression, so I have high confidence that a depression will be named at 5AM or 11AM Monday by the NHC. The models are already plowing this thing into the Leeward islands on Thursday, and near Puerto Rico and Hispaniola around Friday. Right now there is a large ridge to the north of this future tropical storm (Cristobal) which is steering it to the WNW. All indications are that this trend will continue for the next several days, so a hit to the Leeward islands seems plausible later in the week. After that, the track is still uncertain, because of a possible weakness in the ridge caused by Bertha, but it is apparent at the moment that the Leeward Islands, Puerto Rico, and Hispaniola need to watch out for a possible hit from a tropical cyclone Thursday-Friday. As for the intensity forecast, with low shear (5-15 knots) forecasted and Invest 94L moving over waters of 27-28 degrees, I see no reason why this system should not slowly intensify through Friday, and also see no reason why a strong TS or weak hurricane won't be spinning by Friday. Here is a quick look forecast:
0z Wednesday (8PM Tuesday): 13.5N, 47W with winds of 50-55MPH
0z Friday (8PM Thursday): 18.3N, 62.5 W with winds of 70-75MPH.

BERTHA NOTE: Over the last few days Bertha has been sitting and spinning in the same general area while slowly weakening. It has caused large swells and a rip current risk up and down the east coast, which should continue through the beginning of the week, but start subsiding some by Wednesday-Thursday. Bertha will also make a close pass to Bermuda Monday/Tuesday. The island can expect heavy rains, high winds, and high surf. Nothing major to the island, and if anything some beneficial rainfall.

Tuesday Night Bertha Update:

For the whole 5 days, I basically looked at the location of features like ridges and troughs to determine steering currents, which is how I determined which direction the storm would be moving on each day, and looked at the models for guidance on how fast the thing will be moving.
Discussion:
On Wednesday there will be a high to the east of Bertha, and a weakening high west of it, and a bit of a trough between them. Since Bertha is a deep storm, the upper level steering currents will be the main factors that will steer her. So, with the 500MB charts for Wednesday showing a high just of Bertha, Bertha should follow the backside of the high to the northwest. However, since Bertha will be moving into another high that will be in her path tomorrow, I kept Bertha slightly farther left than the model consensus. On Thursday, the setup will be similar. But, with Bertha a little farther north, the anticyclonic flow around the high to the ESE of her at that point will curve her a little more to the north. However, with a high still directly in the storm's path, the storm still cannot escape strait NNE out to sea yet, so I continued with a general NW motion Thursday. On Friday the high to Bertha's north that for the next couple days will keep the storm from racing NE out to sea will weaken and start moving off to the east as a S/W approaches this. This should allow Bertha to slowly curve even more to the north. And next weekend the ridge should be east of Bertha, and Bertha should continue to slowly follow the flow around the ridge to the N. This whole time steering currents will be weak and Bertha will be moving very slowly.
As for intensity on Wednesday shear will be modest, at 10-20 knots which should allow Bertha to hold her current strength and maybe get a little bit stronger, but after that shear will increase which should weaken Bertha.
0z Thu: 85-90
0z Fri: 75-80
0z Sat: 65-70
0z Sun: 55-60
0z Mon: 50-55

Bertha Update: BERTHA NOW A MAJOR HURRICANE!

Last night an eye was attempting to show itself. Today the eye has become well defined, with an extremely organized eye wall, and an extremely organized, symmetrical storm. As of 11AM Bertha had 90MPH winds, but since then Bertha appears to have strengthened very rapidly, and the latest Dvorak intensity estimates are now placing Bertha at a category 3 hurricane. The most of the latest models continue to indicate a curve out to sea, however some are showing the storm stalling out somewhere between the US and Bermuda, so, the US and especially Bermuda need to watch this. While I still think the chances of a US landfall are low, I still cannot rule it completely out. I will have my full updated forecast this evening.

Monday/Monday Night Severe

I am about to crash so I will make this kind of quick:
Areas of special note:
-Slow moving thunderstorms may cause localized flash flooding in the east.
-A MCS may move through WI Monday night with an enhanced wind damage threat and a small flood threat.
-A few tornadoes are possible in the 30% risk area.