Thursday Night - Overcast. Low: 26-30
Friday - Overcast. Slight chance for afternoon showers. High: 40-44
Friday Night - Overcast. Low: 32-36
Saturday - Decreasing clouds. High: 42-46
Sunday - Sunny. High: 58-62
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Discussion:Going into Thursday night we can expect some warm air and moisture to begin to filter in from the South. This means that we will see a slightly warmer night than last but still cloudy and below freezing. Low pressure Friday means that clouds will persist and a small chance for rain in the afternoon into the early evening. Moisture will continue to result in cloudy skies until westerly winds begin to clear them out throughout Saturday. Clear skies Sunday will bring significantly warmer temperatures.
Forecasters: Lieberman, Ritter
Issued: 5:00pm: January 29, 2020
Technical Discussion (The nerdy stuff we are discussing in class)
The 12Z GFS was used in this analysis, supplemented 09Z SREF plumes. The model diagnostic discussion from the WPC said that the GFS was accurate except for a shortwave trough downstream.
The forecast period begins with meridional flow in the Western portion of the CONUS and zonal flow west of the Rocky Mountains at 250MB, 500MB, and 750MB. At 250MB, the subtropical jet max is located over central Mexico. An upper level, deep, long wave trough also extends from southern Minnesota to the southern Baja Peninsula. This trough is expected to move east throughout the forecast period and pass over Columbia between 00Z and 09Z Saturday. This is the most significant event of the forecast period. At 850MB there is a dew point depression below 1 degree Celsius. At 850MB, there is no discernible low level jet. At the surface high pressure systems are analyzed by the WPC in eastern Illinois and southwestern Missouri.
Thursday night will see a deepening of the saturated portion of the air; beginning at around 850MB and extending to about 750MB. This is according the a sounding from the 12Z GFS. This will result in overcast skies. Weakly veering winds will result in some WAA. This means that Friday will be about 6 degrees Fahrenheit warmer than Thursday. Low pressure resulting from the trough discussed earlier will result in the possibility for enough UVM and saturation to result precipitation Friday afternoon into evening. Any precipitation will almost certainly be rain given the temperature profile being above freezing below appx. 875MB and as warm as 41 degrees Fahrenheit at the surface.
After the trough passes, veering winds and WAA will return bringing slightly warmer temperatures on Saturday continuing into Sunday. Moreover, moisture will also exit the region going into Sunday morning resulting in clear skies. Resulting in partial clearing Saturday and full clearing by Sunday. This means that Sunday will be significantly warmer than Saturday.