Monday, February 25, 2019

Tonight - Becoming mostly cloudy. Low: 28-32.

Tuesday - Mix of sun and clouds. High: 52-56.

Tuesday Night - Becoming cloudy with light rain possible after midnight. Low: 38-42.

Wednesday - Cloudy with light rain possible before noon. High: 42-46.

Thursday - Wintry mix possible in the morning and afternoon. High: 38-42.

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After a mostly sunny and average February day, clouds will be on the increase tonight. However, sky conditions will not become completely cloudy until late Tuesday. Lows tonight will be near 30, and highs tomorrow will jump into the mid-50s amid southerly winds. Our next system then comes into the picture late Tuesday night into Wednesday; however, this is not anticipated to have a major impact on the region as our precipitation type would primarily be light rain if any precipitation occurs. Lows overnight Tuesday will be around 40, and there will not be much of a rebound during the day Wednesday. Another system is on tap for Thursday, and as of now appears to bring the threat of a wintry mix for the morning commute.

Forecasters: Brown and Hirsch
Issued: 4:30 p.m., February 25, 2019

Technical Discussion (The nerdy stuff we are discussing in class!)
The main focus of this rather active forecast period is narrowing down our seasonable temperatures. Went with a primarily GFS and GEFS guidance as the large spread in the SREF 2m temperature is cause for some concern. 

For tonight, soundings indicate a deep saturated layer from 250hPa to 400hPa. High clouds present will allow for less radiational cooling than was seen Sunday night into Monday morning. The result will be significantly warmer morning lows. Lows are expected to bottom out right around 30, considerably warmer than the 16 low that Sanborn Field recorded this morning just after sunrise. Partial cloudiness sticks around into Tuesday day with soundings pointing to the exit of high clouds with a drying out of the upper troposphere. Brief clearing looks to occur from 18Z to 21Z Tuesday. High clouds are quickly replaced, though, with a smaller saturated layer just above 850hPa. Southwesterly flow at 850hPa, and the persistent veering profile of the winds will lead to enough WAA to bump our temperatures up into the low 50s by Tuesday afternoon. Temperatures have the potential to creep higher depending on the extent of the clouds during prime diurnal heating hours

Skies become completely cloudy Tuesday night as the mid level clouds remain, and high clouds return between 250 and 350hPa. Thick cloud decks will help trap enough outgoing LW radiation to keep temperatures well above freezing into Tuesday night.

Early Wednesday morning brings our first chance, though slight, for precipitation this forecast period. Soundings favor a saturated layer below 880hPa all the way down to the sfc, with a sliver of negative omega values. Therefore, can't rule out the possibility for some early morning drizzles Wednesday morning. With the temperatures well above freezing, expect only liquid precipitation with no impacts on the morning commute. FROPA on Wednesday morning will set the stage for our next round of precipitation.  There should be a brief lull in precipitation overnight Wednesday prior to the next system passing to the south of the area. A shallow cold airmass should be in place Thursday morning due to Wednesday's FROPA. Warm air advection around 850hPa will lead to a persistent warm nose that will be the primary driver of our precip type. Today's guidance suite tends to favor a more shallow warm layer which will lead to a primarily sleet event throughout the morning and afternoon on Thursday. However, with very subtle changes in the strength of this warm nose leading to drastic swings in the precip type, will have to defer to later shifts to pin down the exact nature of the warm air and resultant precipitation.

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