GREAT LAKES WEATHER: Forecast Update

07 December 2011

Forecast Update

A deep upper level trough at the 500-mb is extending down into the Ozarks this morning. This section of the upper level trough will become a closed upper level low later today as it heads into the southeastern states and passes to the south of the region. This will help kick up that surface low down along the east coast. Latest SPC charts showing a broad jet streak with winds of 150kts over the area right now, and the winds extending down along the Appalacians. 26° at Fort Wayne as of the last update with partly cloudy skies, Toledo sitting at 28° with mostly cloudy skies and Erie at 37° with mostly cloudy skies. Some light rain/snow being reported to our south in Mansfield, have no concern over that right now as the winds will keep that away from the region.

The upper level winds associated with the strong trough will help to keep the clouds in the region for this morning. Haven’t done a lot of work today with the exit time of the clouds, but for now I will keep those at Noon going with RUC guidance.

Strong wave of energy from the upper trough in Canada will start to make its way towards the region today through tomorrow. This wave will pull the trough down into the northern Plains tomorrow afternoon. This is when the weather should start to get interesting for the region.

This upper trough will be accompanied by a cold front which will try to push through the region just ahead of the upper trough.

Upper trough will become better defined late tomorrow and early Friday morning as it gets ready to enter the region. The cold front will be making its way just ahead of the trough and this will have some moisture to work with. As of now, I am expecing that a cluster broad cluster of scattered snow showers will be the culprit for the weather Friday morning as it moves through the area.

Band of clustered snow showers passes through the western half of the region on Friday and then enters the central and eastern half of the forecast region by Friday night. Some of Erie’s snow will come from this, hence why their numbers a bit higher.

I haven’t done much work with the 850-mb temps this morning, though I will have to in order to determine how much lake effect snow will fall in the snow belt areas. When the cold front passes through late Friday night, it will usher in cooler air over the warmer waters of Lake Erie and produce some lake effect snow. The question is how long will the air have to work with before the bulk of the high pressure moves in.

GFS not showing any lake effect on its latest run, but the NAM is keeping it there. SREF also agrees, so for now, I will be keeping the light lake effect in the forecast for the eastern half of the region.

Snow machine will shut off on Saturday afternoon as that high pressure calms the winds down and ultimately changes its direction to a less favourable lake effect event.

Checking with SREF models, looking for snow fall accumulations to be light as of now, though recent model runs have upped them over the past couple runs. Went with generally light accumulations around an inch for the western half of the region, though I will keep an eye on this. Snow fall expectations will be easier to determine tomorrow as the snow makes its way across the northern Plains. For the lake effect snow in the eastern half of the region, again I went with light accumulations around a total of 2-3 inches for the Erie area, and 1-2 for the Buffalo area. I didn’t give Cleveland any, though I will keep an eye on that as well.

Though there are some indications that parts of the western half of the region will see a rain/snow shower mix, the 540-mb line will be far to the south of the region, so again I am going to keep all precip snow for our half of the region.

The biggest question right now will actually not be the precip so much as the clouds. Which clouds will be heavy enough to produce snow and the timing of the clouds is all but easy this morning. The clouds will roll into the western half of the region first – naturally – but the question is how far east will they spread during the day and exactly what time in the afternoon they will arrive. If the clouds show up earlier than what I have no, then I will have to lower the highs about 3-5° in the region. The next question will be how quickly they will exit the region…will it be gradual or abrupt? That too is something that I am focusing on this morning, though the main part of focus will be the timing of the snow and how much lake effect will occur. I am fairly confident in the forecast made a little bit ago, now I am planning to narrow down the time slots.

High pressure builds towards the end of the weekend, calm weather for the rest of the forecast period. I’ll have those revised extended forecasts around 10.00 a.m. this morning, followed by a brief update. Full update at Noon.

But for now, I am Timmy Albertson and that’s the weather! Keep checking back for updates because I’ll have them for you as always.

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Wednesday forecast

Cleveland: Mostly cloudy throughout the day and overnight. Highs in the mid 40's with overnight lows in the mid 30's. Winds NW at 5-10 mph, shifting to the SE at 10-15 mph this evening.
Erie: Mostly cloudy throughout the day and overnight. Highs in the lower 40's with overnight lows in the low to mid 30's. Winds W-WNW at 5-10 mph, shifting to SE at 10-15 mph this evening.
Toledo: Mostly cloudy throughout the day and overnight. Highs in the lower 40's with overnight lows around 40°. Winds SW at 10-15 mph, gusting to 25 mph, then shifting to SW at 10-15 mph this evening.

http://www.rap.ucar.edu/weather/radar/displayRad.php?icao=KIWX&prod=n0r&bkgr=black&endDate=20110419&endTime=-1&duration=0 Link to regional radar.

Extended forecasts (made at 8.07 wednesday)

CLEVELAND
Tomorrow: Mostly cloudy with rain showers developing in the mid morning and then rain showers likely after noon. Highs in the lower 50’s. Winds S at 15-20 mph with gusts of 35 mph possible.
Tomorrow Night: Mostly cloudy with rain showers likely in the early evening, then becoming scattered before midnight and mixing with snow. Scattered snow showers possible after midnight. Lows in the lower 30’s. Winds becoming W at 20-25 mph with gusts of 40 mph likely.
Friday: Mostly cloudy with scattered snow showers possible in the morning, then scattered snow showers likely throughout the afternoon. Highs in the mid 30’s. Accumulations around an inch or two possible. Winds NW at 25-30 mph with gusts of 40 mph likely in the late afternoon.
Friday Night: Mostly cloudy with lake effect snow showers likely throughout the evening and then lessening up after midnight. New accumulations around an inch or two likely. Lows around 30°. Winds NW at 25-35 mph with gusts of 45 mph likely.

ERIE
Tomorrow: Mostly cloudy with rain showers developing in the late afternoon. Highs in the upper 40’s. Winds SE at 15-20 mph with gusts of 30 mph possible by the late afternoon.
Tomorrow Night: Mostly cloudy with rain showers likely throughout the evening, then becoming scattered and mixing with snow after midnight. Scattered snow showers possible towards sunrise. Lows in the lower 30’s. Winds W at 20-25 mph with gusts of 40 mph possible.
Friday: Mostly cloudy with scattered snow showers possible in the morning, then lake effect snow showers likely throughout the afternoon. Highs in the mid 30’s. New accumulations around an inch or two possible. Winds NW at 25-30 mph with gusts of 40 mph likely in the late afternoon.
Friday Night: Mostly cloudy with lake effect snow showers likely throughout the night. New accumulations around an inch or two likely. Lows around 30°. Winds of 25-35 mph with gusts of 45 mph likely.

FORT WAYNE
Tomorrow: Mostly cloudy with rain showers likely throughout the morning and early afternoon. Rain showers becoming scattered in the late afternoon. Highs around 50°. Winds S-SW at 15-20 mph with gusts of 35 mph likely.
Tomorrow Night: Mostly cloudy with scattered rain showers likely in the early evening, then mixing with snow in the evening and becoming all snow before midnight. Scattered snow showers possible overnight. Lows in the lower 30’s. Winds W-WNW at 20-25 mph with gusts of 40 mph possible after midnight.
Friday: Mostly cloudy with scattered snow showers and flurries possible throughout the day. Highs in the lower 30’s. Winds NW at 25-30 mph with gusts of 40 mph likely by the late afternoon.
Friday Night: Mostly cloudy with scattered snow showers and flurries possible in the evening, otherwise lingering flurries after midnight with a low in the mid to upper 20’s. Winds NW at 20-25 mph with gusts of 40 mph likely.

TOLEDO
Tomorrow: Mostly cloudy with scattered rain showers developing in the early morning, then rain showers by noon. Highs around 50°. Winds S-SW at 15-20 mph with gusts of 35 mph possible.
Tomorrow Night: Mostly cloudy with rain showers becoming scattered in the early evening, then mixing with snow in the evening. Scattered snow showers possible after midnight. Lows in the lower 30’s. Winds becoming W at 15-25 mph with gusts of 40 mph possible after midnight.
Friday: Mostly cloudy with scattered snow showers likely in the morning, then lingering scattered snow showers and flurries possible throughout the afternoon. Highs in the lower 30’s. Winds NW at 25-30 mph with gusts of 45 mph likely by the late afternoon.
Friday Night: Mostly cloudy with scattered flurries possible throughout the overnight. Lows in the mid 20’s. Winds NW at 25-35 mph with gusts of 45 mph likely.