Monday, April 9th – Morning Forecast
Tuesday: Partly Cloudy. High: 68°F
Tuesday Night: Partly Cloudy. Low 48°F
Wednesday: Increasing Clouds. High: 66°F
Wednesday Night: Light Rain. Low: 47°F
Thursday: Light Morning Rain then Clearing, Breezy. High 63°F
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General Discussion:
After a brief break in clouds through the afternoon hours today, more cloud cover returns by Wednesday morning. The best chance for rain will be Wednesday night into Thursday with higher rainfall totals held to southern/eastern Missouri.
-Jackson
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Forecasters: Jackson, Beam, Sallot
Date Issued: 04/09/2024 11:00 AM CDT
Technical Discussion:
Key Messages:
- A break in clouds is expected today because of decreasing moisture in the upper levels.
- Uncertainty about the amount of expected rainfall arises with the next low-pressure system as models do not agree on the strength of it.
- Currently, light rain at most is expected, with the highest chance of rainfall Wednesday night into Thursday morning.
A low-pressure system over the Great Lakes region has a large cold front extended through southeastern Missouri as of 14Z Tuesday. This is why upper-level clouds are currently present. As this low traverses east, moisture from 250-500 mb will dissipate and in turn will create a clearing by 18-21Z Tuesday. This will lead to an increase in daytime heating, resulting in a warmup into the high 60s. Attention then turns to Wednesday as another low-pressure system approaches from the Texas and Oklahoma panhandles.
Uncertainty arises by 12Z Wednesday as the NAM and GFS begin to disagree. The GFS displays a stronger system entering from northeast Oklahoma into southeast Missouri that brings widespread moisture, favorable omega, and vorticity over Columbia which would hint at a soaking rainfall by 18-21Z Wednesday. However, the NAM and other CAMs like the HRRR and the NAM 3k all agree that it will be a weaker system and therefore will be held to southern Missouri. The agreement of the weaker system is why the NAM is relied on more during the forecast period.
Soundings display that the NAM keeps lower-level moisture to the south from 12Z to 21Z Wednesday as a persistent dry pocket is present. In the upper-levels, better moisture is present, which is why upper-level clouds can be expected through much of Wednesday. These upper-level clouds will limit daytime heating which is why the high temperature is expected to be in the mid 60s. This dry pocket will limit any potential for rainfall throughout this time as well. This trough continues to move northeast through southern Missouri and Arkansas 00Z-12Z Thursday. At this time, weak lift (-1 to –3 ubar/s) will be present with moisture in the upper-levels. This would hint and rainfall, but the dry pocket from approximately 850 mb to the surface will lead to light rain at most. These factors propagate east by 12-15Z Thursday along with upper-level moisture, which is why rain potential will dissipate and cloud cover will decrease throughout the day.
Future forecasting shifts need to watch the evolution of the low-pressure system over the Texas and Oklahoma panhandles as models disagree about the strength once it impacts Missouri. If it trends toward the implications of the GFS, this would in turn lead to a higher amount of rainfall for Missouri and possibly include a rumble of thunder or two by Thursday morning.
-Jackson