Wednesday, February 12, 2020

Current Conditions at Sanborn Field
Winter Weather Advisory in effect beginning at 9AM 2/12 and ending 12AM 2/13 

Wednesday Night - Overcast. Snow showers tapering off late. 
Low: 8-12

Thursday - Becoming mostly sunny. High: 12-16  


Thursday Night - Clear and cold. Low: 2-6

Friday - Sunny. High: 28-32


Saturday - Mostly cloudy. High: 40-44

Thanks to for the icons!

The main concern we have been looking at today is the ongoing snow event. Snow will continue into tonight, bringing an additional 1-3 inches. Temperatures will drop rapidly after midnight due to an arctic cold front passing through the region. By Thursday morning, all the precipitation should be exiting central Missouri as the front pushes available moisture to our southeast. However, the front, which will usher in Canadian high pressure, will bring central Missouri some of the coldest air of the season Thursday night into Friday morning. This cold push will be short-lived, with warmer temperatures returning on Saturday.
Forecasters: Pauley, Vanderpool, Ritter
Issued:  5:00pm: February 12, 2020

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

It is a rather interesting setup over mid-Missouri this afternoon. Composite radar shows a shield of precipitation (supported by isentropic upglide and strong moisture transport courtesy of the 850 mb low-level jet) shifting off to the north and east into Illinois. This precip shield was our primary source for precipitation for the first 2/3 of the day, but pockets of dry air have mixed into the system, leading to breaks in the precipitation as of 21/22z. We are not done yet, for a region of banded snow located over KS and northwestern MO is moving eastward. Short-range model guidance indicates this frontogenetically-forced snow moving into mid Missouri this evening.

For tonight, a developing surface low over Louisiana will intensify and shift northeast. A very potent Canadian high is currently located over Saskatchewan, with its associated arctic cold front stretching through IA and NE. The aforementioned banded snow will move into central MO, supported by the strengthening storm system to our southeast. The bulk of this snow looks to come to an end shortly after midnight, but not before dropping an additional 1-3 inches of accumulation (for a storm total of 2-5 inches). The incoming arctic front will blast through the region shortly thereafter, causing rapidly-dropping temperatures and an increase in wind. Any remaining water or slush will freeze quickly. Lows behind this front will bottom out in the upper single digits to lower 10s.

Thursday and Thursday night, we will be firmly entrenched in the Arctic airmass. GFS/HREF guidance suggests that the surface pressure at the center of the surface high will approach 1040 mb, which is quite impressive. The strength of the arctic airmass in place will, in combination with snow on the ground, serve to keep highs tomorrow in the low to mid 10s. Lows Thursday night and Friday morning will hit the single digits, with a small (but not negligible) chance that we drop into the negatives.

Thankfully, the Canadian surface high will not remain in place for very long. It will shift east Friday into Saturday, allowing return flow on the backside to boost temperatures starting Friday afternoon. Saturday will likely see even warmer temperatures, with highs in the lower 40s. The 12Z GFS generates a neutrally-titled trough at 500 mb which will lead to some upward motion in the mid-levels of the atmosphere. Combined with just enough moisture between 850 mb and 700 mb, we will likely see some cloud cover Saturday.

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