Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Jan 23 2024 08:23:40 FOUS30 KWBC 230823 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 322 AM EST Tue Jan 23 2024 Day 1 Valid 12Z Tue Jan 23 2024 - 12Z Wed Jan 24 2024 ....THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF EASTERN TEXAS INTO THE ARK-LA-TEX AND SURROUNDING PORTIONS OF NORTHWEST LOUISIANA AND SOUTHWESTERN ARKANSAS... ....Eastern Texas to the Mid-South... A brief window of relatively drier conditions is expected for much of the early morning as the shortwave impacting the region overnight lifts to the northeast through the mid Mississippi Valley. However, heavy precipitation is expected to quickly redevelop back to the west as upstream energy continues to amplify an upper trough moving across the Southwest. Amplifying southerly flow will support a resurgence of deeper moisture across eastern Texas and the lower Mississippi Valley, as a stronger shortwave trough ejects eastward into the Southern Plains. PWs over 1.5 inches (2.5 standard deviations above normal) will begin to extend north across eastern Texas and the lower Mississippi Valley late today into early Wednesday. This moisture (along with ample instability and large-scale ascent) will support the development of organized convection around midday across eastern TX. Rainfall rates of 1-2"/hr will be supported by the environment, as convection becomes linear and fairly progressive towards the east. Soils have become locally saturated over the past 24 hours with 2-4" of rainfall having already fallen (per MRMS estimates) resulting in FFGs as low as 1-2". As a result, numerous flash floods are likely from portions of eastern TX through the Ark-La-Tex. This area with the highest risk for flash flooding is generally encompassed by the Moderate Risk, and includes the region where 00z HREF exceedance probabilities are maximized (with 40-km neighborhood probabilities of up to 80% for 3" exceedance and between 20-40% for 5" exceedance). Given the potential for localized totals of 4-6" over already saturated areas, some locally significant flash flood events are possible (particularly over more sensitive low-lying areas and poor drainage urbanized terrain). ....Southeastern Arizona... An amplified upper trough along with anomalous moisture will continue to support precipitation across the region early in the period. While widespread heavy amounts are not expected, some additional locally heavy amounts (1"+) may produce some isolated runoff concerns early in the period. Churchill/Pereira Day 2 The Day 2 outlook will be updated by 0830Z. Day 3 The Day 3 outlook will be updated by 0830Z. Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!4KPbERVb6u-VhtRH_PO_Pfp8mNrNoLeakiVdqMX1n4t1= XvRwmQHA3ydkEsNlGzAzO6Fm16xkLbv5784xJdt7H7YowEw$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!4KPbERVb6u-VhtRH_PO_Pfp8mNrNoLeakiVdqMX1n4t1= XvRwmQHA3ydkEsNlGzAzO6Fm16xkLbv5784xJdt7ivUUsQI$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!4KPbERVb6u-VhtRH_PO_Pfp8mNrNoLeakiVdqMX1n4t1= XvRwmQHA3ydkEsNlGzAzO6Fm16xkLbv5784xJdt7IONhROg$=20 $$ =3D =3D =3D To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. --- SBBSecho 3.14-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .