Friday, January 25, 2019

Tonight - Cloudy. Low: 14-18.

Saturday -
Cloudy during the morning, then becoming mostly cloudy in the afternoon. Snow showers before noon. High: 30-34.

Saturday Night - Becoming cloudy overnight with flurries by dawn. Low: 24-28.

Sunday -
Cloudy with flurries in the morning. High: 38-42.

Monday - Cloudy and breezy. Rain in the early morning changing to a wintry mix by midday. High: 32-36. 

Thanks to for the icons!

This weekend will mark an active weather period for Mid-Missouri with several small systems speeding through. Tonight will be cold and cloudy out ahead of our first system, but don't expect snow until daybreak Saturday. This snow will be light in intensity and short in duration, which may allow even some clearing by Saturday afternoon. Temperatures Saturday afternoon will be near this afternoon's mark. Cloudy skies will persist through the remainder of the period, with a brief shot at snow Sunday morning, and then another, more substantial chance of mixed precipitation Monday. Temperatures will push to near average Saturday before falling through the day Monday ahead of the next cold snap.

Forecasters: Ritter, Munley, and Hirsch
Issued: 3:30 p.m., January 25, 2019

Technical Discussion (The nerdy stuff we are discussing in class!) 
After a frigid night last night, temperatures have rebounded nicely to near freezing thanks to abundant sunshine throughout the day today, along with the passage of a weak warm front. However, if the sun makes any appearances this weekend, they will be short-lived, as an active weather pattern will impact the Mid-Mississippi Valley this weekend, bringing ample cloud cover and chances for brief, light precipitation. Our first chance of wintry precipitation currently resides near the Missouri-Iowa border. Per WPC analysis, a cold front and associated low pressure center were draped across this border. Satellite imagery shows this system is producing a fair swath of cloud cover from north-central Kansas to Chicago. As this system pushes South, GFS shows a small divergence maximum at 250 hPa developing over central Missouri early Saturday morning. Around the same time, it shows a 500 hPa vort max will develop over our area. Furthermore, the GFS suggests there will be plenty of moisture and sufficient lift at 700 hPa for precipitation to fall. The main question with Saturday's precipitation, though, is whether or not the lowest 100 hPa of the atmosphere will be moist enough to support it. GFS Skew-T's show a significant dry layer in place around dawn Saturday, moistening quickly around mid-morning before the upper levels dry out around lunchtime. If the GFS is to be believed, there would only be a small window of opportunity for any precipitation to occur. QPF from both the GFS and SREF are not very impressive either, showing less than 0.05 inches of liquid equivalent. As the system clears central Missouri Saturday afternoon, there will not be a powerful push of cold air. Instead, temperatures should hold steady near freezing, and there may be some clearing as moisture leaves the region. However, by Saturday night, the clouds return ahead of another system. again, per the GFS, there will be divergence at 250 hPa, a vort max at 500 hPa, and plenty of moisture at 700 hPa, but again, the lowest 100 hPa will be dry. QPF from GFS and SREF is even less Sunday therefore, have only mentioned flurries for Sunday morning. 

Sunday remains cloudy as 700 hPa moisture remains in place. As a high pressure center passes to the Northeast, flow should switch from northwesterly to southwesterly, leading to a period of WAA, and thus, temperatures will return to average on Sunday. However, the next outbreak of arctic air will plunge out of Canada and into the Midwest on Monday. Ahead of this, precipitation will develop as there will be divergence at 250 hPa and moisture and life at 700 hPa;. Temperatures will likely be above freezing at the onset of the precipitation, but as the system passes through, flow will switch from southwesterly to northwesterly, leading to CAA and falling temperatures. This means that, while precipitation will begin as rain on Monday, there will likely be a transition throughout the day to a wintry mix and perhaps all snow by evening. QPF from the GFS and SREF are a bit more impressive with this event, with around 0.10 inches expected across our area. Due to uncertainty regarding this event, there may be many changes made to the forecast by the Monday morning shift.


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