Current Conditions at Sanborn Field
Tuesday Night: Scattered showers. Low: 42
Wednesday: Scattered Showers. Chance for t-storms. High: 72
Wednesday Night: Scattered showers. Low: 63
Thursday: Scattered showers. High: 70
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Discussion:
Rain rain rain. Oh, and more rain. Lots of rain this week so bring your umbrella with you every day. High temperatures will be in the low 70s Wednesday and Thursday in conjunction with this rain. Most of the time the rain will be light but could be stronger Wednesday morning and thunderstorms are likely Thursday night. Some of these storms could become severe so keep an eye out on the weather as you go about your evening.
-Smitty
Forecasters: McCormack, Peine, Smith
Date Issued: 03/21/2023 5:00 PM CDT
At 250mb, near-zonal flow exists across much of the CONUS which has kept temperatures in the mid-40s this afternoon. However, this pattern will begin to change as an upper-level trough begins to develop over the western United States overnight tonight and into tomorrow, amplifying our flow aloft to include a more southwest component. Even though precipitation is beginning to exit in Missouri, cloud cover will continue to remain overhead tonight as a warm front will lift north into the region Wednesday morning, advecting more moisture from the Gulf of Mexico. The best chance for showers and thunderstorms late Tuesday night will be north of our area as the warm front begins to situate across northern Missouri. A few rain showers are possible for mid-Missouri as we are just to the south of the warm front, but accumulation will likely be below 0.1” overnight. With surface winds out of the south-southeast around 10kts and stratus clouds for the entire night, temperatures Tuesday night will gradually warm up overnight and be near 50 degrees Wednesday morning.
For Wednesday, the upper-level trough will continue to be more pronounced over the western CONUS and help advect significantly warmer air out of the southwest. Even with cloud cover still present due to the stalled front over the Missouri/Iowa border, temperatures will be 10-15 degrees above average (avg. high 58) Wednesday afternoon as 850mb winds are out of the southwest at 35-40 kts. Dew points will rise into the upper 50s and low 60s during this time and surface-based CAPE values are forecasted to be between 1000-1500 J/kg. However, capping is expected to be strong enough to prevent much from firing. Expect mostly cloudy conditions on Wednesday with a slight chance for a pop up thunderstorm.
With stratus clouds continuing to dominate the central CONUS and southwesterly flow aloft down to the surface, Wednesday night low temperatures will be 20-25 degrees above average (avg. low 37). With the trough slowly developing over the desert southwest, our focus shifts to a broad surface low that begins to form east of the Rocky Mountains. Associated with the aforementioned low, a cold front will push southward from northern Missouri, allowing our surface winds to be more out of the west late Wednesday night into early Thursday morning. This setup is slightly more favorable as dew points will once again be in the low 60s with surface-based CAPE values between 500-1000 J/kg. However, a forcing mechanism will be present closer to our area as the cold front is forecasted to move through central Missouri late Thursday morning. Furthermore, the aforementioned trough will exit the western CONUS and divergence aloft associated with it will shift east into portions of Missouri which would support rising air. A few pop up thunderstorms are possible out ahead the front early Thursday morning with the greatest concern being small hail possible with some of these storms. Rainfall totals are expected to be less than 0.1” as convection is expected to be short lived as well as lower dew point temperatures for our area after the frontal passage.
Thursday’s high temperatures will be determined by the timing of the cold front. Most models have the cold front to our south before the afternoon, so expect a morning high temperature in the mid 60s before northwesterly winds filter in on the backside of the front, advecting cooler air for northern and central Missouri. As the cold front continues to slowly drift south, a surface low pressure will develop near the Texas panhandle, ejecting warm moist air out ahead of it. As of now, southeast Missouri will be sandwiched between cooler air from the north and warmer air from the south, setting up a stationary front that will have plenty of Gulf of Mexico moisture to work with. This will begin to set up late Thursday evening and produce the risk of heavy rainfall during the overnight hours in southeast Missouri. As for our area, we are still expecting rainfall Thursday night, but rainfall totals should be between 0.25-0.5” due to the location of the stationary front and the brunt of the moisture being further south. Confidence is low with the location of where higher rainfall totals could be, so if the front shifts further to the north, then I would be more concerned with the possibility of flash flooding. However, most of the models have the heaviest rain south of I-44. With northerly winds and rain likely most of the night, low temperatures are expected to cool into the low 40s.
Future forecast shifts should monitor the position of the stationary front as rain chances will continue for our area throughout the weekend because of this pattern.
-McCormack
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