Current Conditions at Sanborn Field
Tuesday: Rain. High: 71
Tuesday Night: Partly cloudy. Low: 60
Wednesday Night: Partly cloudy. Low: 45
Thursday: Sunny. High: 66
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Discussion:
Rain is finally coming to mid-Missouri today and tomorrow. Today's rain will be light and persistent, ending this evening. This will be followed by the passage of a cold front tomorrow morning, bringing a band of rain and possible thunderstorms that will end after noon. Following the passage of the front will be few clouds and cooler temperatures.
Forecasters: Ritsema, Clark, Baker
Date Issued: 10/11/2022 9:00 AM CDT
For this forecast we decided to use both the NAM and GFS, as both models agreed on the timing of the frontal passage, the distribution of moisture in the mid- and lower levels, and areas of vertical motion. We decided to lean more towards the GFS because NAM soundings for this forecast period showed CAPE increasing to 2500 J/Kg overnight Tuesday, which ultimately makes us feel uncertain in the NAM's capabilities in initialization for this forecast run.
Starting off at 12z Tuesday, 700 and 850 mb relative humidity values of near 100% stretch from Indiana and eastern Iowa down to central Texas, completely covering Missouri. This broad area of saturation corresponds with high 500 mb vorticity, 700 mb vertical velocity, and the low level jet at 850. As the day progresses, the bulk of the low-level moisture will move off to our east, leaving us with a few clouds at 700 mb.
Overnight Tuesday we will see moisture at the low- and mid-levels dissipate ahead of the frontal passage Wednesday morning. Some clouds will remain due to residual moisture and moderate vertical motion at the 700 and 500 mb levels. Early Wednesday morning we see vertical motion increasing just before the cold front passes, which along with increasing moisture in the same area will lead to rain and embedded thunderstorms along the front.
This front is driven by a trough at 250 mb centered over Manitoba. This trough will bring the polar jet down to Missouri, providing our region with cooler temperatures and drier air. This is evident in soundings from Wednesday 21z, where our low-level moisture content decreases after winds transition to the northwest. Due to this, 850 mb temperatures dropped around 7 degrees behind the front around 16-18z Wednesday.
Tuesday's rainfall should amount to 0.1" to 0.2", and Wednesday's rainfall should amount to 0.1" to 0.2" as well.
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