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.
