Current Conditions at Sanborn Field

Flood watch in effect until March 13, 6:00PM CST

Friday Night - Clouds and rain. Low: 42-46

Saturday - Cloudy with isolated showers. High: 48-50

Saturday Night - Cloudy with increasing rain chances by morning. Low: 42-46

 

 

Sunday - Cloudy and windy with moderate to heavy rain. High: 48-52

Monday - Mostly cloudy and windy with isolated showers possible. High: 58-62

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Discussion: 

 

A soggy weekend is in store for Columbia and the majority of Missouri. A stalled boundary draped over southern Missouri will help to fuel rainfall chances along and south of the I-70 corridor this evening and tonight with a quarter of an inch possible locally. Saturday will remain cloudy though rain chances in Columbia will lessen as the bulk of rainfall meanders south with the aforementioned boundary. Temperatures tonight and tomorrow will remain seasonal for the ides of March. Rain chances will increase Saturday night into Sunday as we spring forward into Daylight Savings Time. This is due to the next weather maker in the form of a vigorous mid-latitude cyclone that will invade the Midwest from the west over the course of Sunday. Moderate to heavy rain can be expected after noon Sunday through midnight. Total accumulations from the weekend will fall around 1.25 inches. Temperatures will rebound slightly Monday as rain chances diminish in time for the new work week to start.

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Forecaster: Bongard

Issued: 5:00 PM CST 12 March 2021

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

GFS continues to model the current conditions fairly well in terms of initial conditions as well as placement of the low pressure system to the west. Therefore, GFS will help in diagnosing the main challenges of this forecast period which will center on rainfall accumulations and chances through Monday.

The 250-mb level places the region beneath the ridge in the trough-ridge pattern across the CONUS. A jet streak stretching from the northern Plains into New England lends divergence overhead and across northern Missouri in its right entrance region. The weather maker for later this weekend in the Midwest is spinning cyclonically over Nevada. The initial divergence over Missouri is and will continue to aid in precipitation development this evening and tonight until the associated jet streak retreats east. The upper-level low will spin across the Rockies and into the Central Plains by 18Z Sunday bringing with it plenty of divergence aloft and a new jet streak in the cyclones downstream flow whose nose push across mid-Missouri Sunday night into Monday.

Vorticity along the stalled boundary draped over southern Missouri is contributing necessary dynamics for precipitation development across central and southern Missouri this evening. This initial vorticity will advect to the northeast by Saturday morning as the encroaching system from the west begins to influence flow and advection over the Midwest by Saturday night. Plentiful spin over the area will be available Sunday after 18Z coinciding with what looks to be the best chances for heavy rainfall in central and southern Missouri. 

The moisture profile in the lower levels of the atmosphere over Columbia is present both in the horizontal in the form of 700- and 850-mb charts as well as in the vertical in the form of GFS model soundings. The profile remains saturated through the early morning hours. Rainfall accumulations this evening and overnight look to be around 0.25 inches. A dry layer in the mid-levels will help to inhibit moderate rainfall Saturday though an isolated shower cannot be ruled out. This dry layer will persist until sunrise Sunday morning when an LLJ housed in the warm sector of the invading cyclone will help re-saturate the profile just in time for the heavy rainfall event in central Missouri after 18Z Sunday. Rainfall will persist into the early morning hours when dry slotting behind the cold front will push necessary precipitation ingredients out of area. Additional rainfall Sunday into Monday will stack an additional 1.0-1.25 onto what falls this Friday night into Saturday. Will keep a chance for rain in the Monday forecast due to wrap around moisture on the western flank of the mature cyclone.   

Worth noting here is the lack of convection in the forecast. This is due to an absence of CAPE values overhead for the extent of the forecast period despite healthy moisture numbers (PWAT) and forcing (omega) especially Friday and Sunday evening. K index values point to a heavy rainfall event for central Missouri Sunday after 18Z potentially prompting the expansion and continuance of the current Flash Flood Watch the NWS has issued for the Columbia area. While flooding may be a concern, severe weather does not look to be an issue for the area at this time.