GREAT LAKES WEATHER: Evening Post

27 November 2011

Evening Post

This update will focus on our next low pressure system that will affect the region starting tomorrow night and throughout the day Tuesday and into Wednesday morning. This system will put us into the seasonal weather and it will be an interesting one nonetheless. Lets get right into typing about it:

Cold front moving through the region this evening will start to stall out over the eastern half of the region tonight. This stalled front will extend all the way from the region down into the southeastern states along a narrow, yet nearly vertical upper level trough. This upper level trough is where we can expect to see our next low pressure system develop starting tomorrow.

This surface low will begin to develop along the southern section of this stalled out front, and as it does so a nice sized upper level low will develop right behind it. This upper level low will continue to intensify as its surface low deepens as well. The low pressure centre will organize itself during the morning tomorrow and then it will start to make a beeline – nearly due north – towards the region. The upper level low will nearly be on top of the surface low which to me indicates that occlusion will start to take place (a cooler air mass will wrap around the low).

Checking with my pluthera of short range models (though I hate them, for this forecast they are necessary) and they are starting to come into a near agreement with this system.

850-mb temps of 32°F associated with this upper level low will start to mix down to the surface down in Tennessee area. This will start to happen as the first bands of the rain shield make it into the region.

The trickiest part of the forecast will be Tuesday night when the centre of low pressure pushes into the region. Cold air advection will take place in the region, mainly in the western half of the region and this is going to push the surface temps down into the 30’s, and with the 850-mb temps near 32°F I am expecing that some of the rain on the back edge of this system will turn to snow.

The 540-mb are close enough to the forecast area at this time that is looking likely. However this is going to take place as the low exits the region and the precipitation starts to become widely scattered. This is why, at least for our part of the weather world, that the snow wont really accumulate other than a dusting in the western half of the region.

Upper low begins to weaken as the surface low finishes its occlusion and another surface low takes its place and heads to the northeast on Wednesday. An area of high pressure will build up in the region on Wednesday afternoon and overnight Wednesday and will allow for a cooler end to the work week.

Back to Tuesday night now, the SREFs are generally in a state of almost agreement with the location of the upper low and the surface during this time. Looks like the surface low will pass through the eastern half of the region overnight Tuesday with precipitation to its north, east and west and drier air trying to pull in from the south. Heavy rains will be the flagship with this low as it nears the region, and rainfall totals may reach a half inch or possible ¾ of an inch by the time all is said and done.

Checking with the upper levels of the SREFs this evening, they have the 540-mb temps staying out of the region during Tuesday night.

If that happens, this will mostly be a rain event with some brief snow mixing down in southwestern half of the forecast area. The SREF is showing a very nice temperature difference with this upper low on Tuesday night as it moves through the region with most of the region near to the 32°F at the 850-mb level. This could result in some mixing down in the region which again, gives us that possibility of some snow.

Short range GFS indicating generally the same system, but with temperature a tad bit different than that of the SREF. Unlike the SREF, the GFS has the 540-mb line pulling into the region by late Tuesday night and this is telling me that the GFS is expecting a decent amount of cold air advection to take place. This shows us that snow will be likely in accordance with the GFS…

Checking with the NAM this evening, things are a little different with the 540-mb line focused generally over Ohio and western Indiana on Tuesday night – this indicates to me that a rain/snow mix will be likely.

Right now I will keep the western half of the region with general lingering snow showers on Wednesday morning as the low pulls out of the region, otherwise this system will be mainly rain showers.

So how is my confidence with this low pressure system? Actually, I am confident with the timing and the overall general course with this system, however the only thing that I am still questioning is the exact timing of the snow transition and just how much snow we’ll be seeing in proportion to the rain. Regardless, I am not expecting that much snow accumulation with a dusting amount being the most we could be seeing.

Typical November weather, eh.

I’ll have a complete update coming up for you in the morning around 6.00 a.m. as well as revised extended forecasts and another update regarding our next low pressure system. But for now, I am Timmy Albertson and that’s the weather!

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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.