Wednesday, November 20, 2019

 Wednesday - Increasing Clouds. High 62-66
 Wednesday Night - Cloudy. Rain after midnight. Low: 52-56 
 Thursday - Mostly Cloudy. Early morning rain. High: 58-62 
Thursday Night - Cloudy. Low:  30-34
Friday -  Cloudy. High: 40-44

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Wednesday will see southerly winds throughout the day ahead of an approaching system of low pressure.  This will keep temperatures up during the day, to a rather nice mid 60s.  Rain is expected to begin ahead of a cold front to the west late Wednesday night.  Precipitation is expected to taper off Thursday morning, as the cold front passes overhead.  This cold front will drop temperatures starting around noon, and continually dropping them through Thursday night.  Winds will remain out of the north on Friday, once again keeping temperatures down, along with the expected cloud cover.
Forecasters: Heaven
Issued:  10:00a.m. November 20, 2019

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

WPC model diagnostics discussion indicates a general blend for the current forecast period and system, and as such it will be used for this forecast period.  The models used are the GFS and the SREF.

Wednesday temperatures are expected to get quite warm, as a stationary front just off to the northeast has finally started to advance to the northeast as a warm front.  WAA behind the front is quite strong, with decent surface winds out of the south, and an 850mb jet pushing 60 knots.  This WAA helps to set up the rainfall event that is expected overnight into Thursday.  Soundings in the last few model runs have been picking up on around 50 MUCAPE and no CIN, enough to get some rumbles of thunder out of this rainfall.  Vertical velocities at 700mb seem to have increased also, indicating some convective precipitation is very possible.  This precipitation is expected to be quite widespread through Thursday morning, with SREF and GFS both indicating about half an inch of precipitiation.

Thursday morning will see our rain start to end, and the looming cold front finally pass around noon.  The high temperature on Thursday is expected to happen in the morning, as the afternoon will have CAA keeping temperatures down quite a bit.  This CAA behind the cold front is expected to be quite strong, pushing temperatures down into the 30s Thursday night.  Precipitation has been taken out of the forecast for Thursday, as SREF and GFS both seem to have removed rain for the most part; soundings also indicate that a large dry layer has appeared at the surface that cannot be eroded, along with less overall saturation than the previous forecast soundings indicated. 

Friday will see the coolest temperatures of the week, as it will be the first full day in CAA behind the cold front from Thursday.  Temperatures are not expected to get out of the mid 40s, as Columbia will be cloudy and have CAA.  Precipitation seems rather unlikely at the time this forecast was made for Friday, however future shifts will need to keep an eye on possible precipitation.  There are hints at precipitation, however nothing too convincing yet. 

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