Tuesday, August 27 – Morning Forecast
Tuesday: Partly cloudy. Pop-up afternoon/evening showers and thunderstorms probable. High: 98°F
Tuesday Night: Decreasing clouds through the night. Low: 74°F
Wednesday: Mostly cloudy. Scattered showers and thunderstorms mid/late afternoon. High: 94°F
Wednesday Night: Cloud cover decreases. Isolated showers and thunderstorms. Low: 74°F
Thursday: Partly Cloudy. Isolated thunderstorms return in the evening. High: 95°F
=============================================================================
General Discussion:
A heat advisory is in effect until 8 PM tonight. Be prepared for rounds of showers and thunderstorms throughout the next few days. Heat remains throughout the week leading to hot afternoons and increased humidity. Summer is here to stay for the next few days!
-Chirpich, John, Beach, Alcorn
=============================================================================
Forecasters: Chirpich, John, Beach, Alcorn
Date Issued: 08/27/2024 9:00 AM CST
Technical Discussion:
The GFS was consulted for this forecast as it more accurately predicted Tuesday’s overnight low temperature. The main focus of the forecast are the rounds of showers and thunderstorms along with oppressive daytime temperatures.
At 250MB the overall flow over Missouri is driven by a high-pressure system over the Midwest and a low-pressure system over Texas. These will act more as sources of moisture rather than divergence or vorticity. The upper-level high/low features extend down into the lower levels, with the main weathermaker for the forecast period being the shortwave trough found at 500MB. A strong ridge is in place over the Mississippi River Valley, allowing for ample daytime heating and above average temperatures (Avg: 88) throughout the rest of the week. The placement of this ridge, combined with the low over Texas, also creates a moisture transport highway into northern Missouri that will be the source for some unsettled afternoons in the forecast period. The greatest amount of moisture over the forecast area was at 700MB, with drier lower-levels (specifically with 850MB demonstrating limited moisture).
Due to adiabatic cooling at the surface, expect clearing conditions in the mornings as clouds lower and dissipate as the temperature falls. Morning lows stay near the middle 70s with afternoon temperatures rising into the mid-to-upper 90s. This excessive daytime heating will allow mid-Missouri to reach convective temperatures Tuesday-Thursday, and rising dew points will lead to thunderstorm development for the afternoons of the next few days. Regardless of modest instability and the presence of shortwave troughs in northern Missouri, moisture content at the surface remains lackluster, which will dictate the “pop-up” nature of Tuesday PM / Wednesday PM showers and thunderstorms in the forecast area.
Soundings indicate a strong inversion cap in the early mornings of the forecast period that erodes by the afternoon, allowing for pop-up showers and thunderstorms for Tuesday, Wednesday, and Thursday afternoon/evenings. Due to limited moisture at the surface, rain totals for each afternoon/evening will stay near trace amounts. Future forecasters should watch for a deepening low late into Thursday evening which could strengthen the potential for showers.
-Chirpich, John, Beach, Alcorn