Wednesday, December 4, 2019

Wednesday Night- Partly cloudy. Low: 34-38

Thursday- Sunny, then increasing clouds. High: 56-60

Thursday Night- Cloudy with rain. Low: 34-38

Friday- Cloudy, then becoming sunny. High: 40-44

Saturday- Sunny. High: 46-50

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Tonight, partly cloudy skies along with a southerly wind will not allow temperatures to drop too much. Thursday will start out sunny before increasing cloudiness begins around noon. Warm air moving through the region will allow for above average temperatures. Thursday night, rain is expected to begin after midnight with accumulation totaling a tenth of an inch. Early Friday, a cold front will move through the area, causing morning temperatures to dip before warming up as the day progresses. A northerly wind will cause temperatures to rise little, but skies will begin to clear after the cold front passes. Saturday will be nicer with sunny skies and a southerly wind.

Forecasters: Abruzzo, Dowell
Issued:  5:00 pm, December 4, 2019

Technical Discussion (The nerdy stuff we are discussing in class)

WPC guidance indicates preference towards a general model blend with less weight given to the GFS, and as such, the forecast was made primarily using the 18Z NAM and 15Z SREF, with some consideration towards the 18Z GFS.

For tonight, model soundings indicate areas of high moisture, mainly around 400 mb, that will lead to some cloud development, but not enough to make the sky overcast. Winds will begin westerly before backing and becoming southerly as the area begins to be influenced by a surface low located over the Central-Southern Plains. 

As we move into Thursday, WAA will begin over the area due to the same surface low in the Central-Southern Plains. Model soundings show a relative dry morning, thus causing sunny skies. In the afternoon, though, increasing moisture around the 375 mb and the 700 mb levels will cause cloud development, more than what will be seen the night before. The timing of this development is paramount and will dictate what the high temperature for Thursday. Currently, we are forecasting a high temperature of 56-60; we will revise this if there are changes to the timing of cloud development or a change in strength in WAA over the area.

Thursday night, the atmosphere will begin to saturate and cloudy skies will develop ahead of a cold front that is expected to pass over the area at around 6 AM Friday locally. Rain is expected to begin around midnight locally. Precipitable water is low, only about 0.8 inches. This, coupled with only a few hours of expected rain will lead to an anticipated total rainfall of about a tenth of an inch. No storms are expected with this rain as CAPE values are little to none.

Friday morning will see the end of WAA as cold frontal passage begins over the area. Wind direction will shift from southerly to northerly, and frontal passage will bring temperatures to the lowest for the day, even cooler than the forecasted low of 34-38 Thursday night into early Friday morning. After frontal passage, weak CAA will start and keep temperatures low, despite the atmosphere drying out and clearing skies starting mid-morning. Thankfully, CAA will not last long, as it will be ending that night.

Finally, Saturday will be somewhat warmer as the first full day of sunny skies will allow temperatures to rise into the high 40s. Model soundings indicate a relatively dry atmosphere, so little to no cloud development is expected. Additionally, a surface high located over the Great Lakes will bring southerly flow to the area, but no advection is expected at this time.

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