Wednesday, March 11, 2020

Wednesday Night -Clear with passing clouds. Low: 44-48

Thursday - Rain with possible thunderstorms. High: 62-66


Thursday Night - Decreasing clouds. Low: 34-38 

Friday - Partly sunny with clouds increasing. High: 48-52

Saturday - Rain. High: 36-40

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Tonight, temperatures will drop into the middle to upper 40s. Skies should remain mostly clear, as there will be little moisture in the atmosphere. Tomorrow, an approaching storm system (along with a cold front) will bring a chance of rain and isolated thunderstorms to mid-Missouri. This cold front will usher in colder temperatures for Thursday night and Friday. On Saturday, another storm system will move into the central plains, bringing much colder temperatures and widespread soaking rain.
Forecasters: Vanderpool, Pauley, Ritter
Issued:  5:00pm: March 11, 2020

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

WPC model diagnostics advocate a 12z GFS/ECMWF/CMC blend. The GFS seems to have a good handle on the current setup over the CONUS, so this shift has elected to use the 12z GFS run for deterministic guidance. For ensemble guidance, the SREF, HREF, and GEFS were all used.

18z surface analysis indicates a very weak surface high over NE Missouri. This high has made for dry conditions and mostly calm winds this afternoon in and near Columbia, so insolation has been the main reason for this afternoon's rapid warm-up. Upper air analysis at 250-mb reveals a fairly large ridge centered over the southern Rockies, which is progged to move east over the next 24 hours. 500-mb heights and vorticity do not reveal this ridge as clearly, with a mostly zonal pattern over the central CONUS at that level. Further down, moisture looks fairly limited at 700-mb and 850-mb, and with no lift in the region until tomorrow, conditions will stay dry over the next 12-18 hours.

Tonight, calm winds near the surface will continue. GFS soundings and ensemble model guidance indicate that skies will remain mostly clear. Temperatures will drop into the mid to upper 40s overnight, almost entirely courtesy of radiational cooling.

Tomorrow, things will get more interesting. A surface low will eject out of southeastern Colorado beneath a broad 500-mb trough. The low will cause a cold front to pass through central Missouri, with FROPA most likely between 18z and 21z tomorrow afternoon. Temperatures out ahead of this low will warm into the low to mid 60s with fairly stout warm air advection. Moisture returns should be sufficient for overcast skies and afternoon showers (and a few thunderstorms) particularly near and along the approaching cold front. The SREF pegs most unstable CAPE (MUCAPE) values near 500 J/Kg, but GEFS, GFS, NAM, and HREF model guidance are all hovering between 0 and 100 J/Kg. Thus, instability may be sufficient for isolated thunderstorms, but the threat of severe weather is questionable. Never the less, the SPC has outlined areas just south of Columbia in a marginal severe weather risk, primarily for damaging winds and isolated tornadoes. This should be watched out for, especially given more than sufficient shear and our proximity to the center of the low.

For Friday, conditions will be calmer. Then, another low will eject into the Midwest on Saturday, spreading broad moisture and lift out over Missouri. We will be firmly in the cold sector of this low, leading to temperatures in the mid to upper 30s (and perhaps near 40). Thus, a cold rain is expected for Saturday, with snow possible a few counties to our north.

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