Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Apr 22 2025 07:59:29 FOUS30 KWBC 220759 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 359 AM EDT Tue Apr 22 2025 Day 1 Valid 12Z Tue Apr 22 2025 - 12Z Wed Apr 23 2025 ....THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF THE TEXAS PANHANDLE INTO WESTERN OKLAHOMA AND THE CENTRAL GULF COAST... ....Texas and Oklahoma... A west-east orientated warm front paired with a dryline over West Texas will maintain an environment conducive for convection through the night. An expeditious shortwave ejecting out of the Southern=20 Rockies will navigate over the Caprock aiding in focused mid-level=20 ascent within the confines of the boundary and relative instability maximum situated near the front and points south and east.=20 Scattered convection will likely billow up off the eastern New Mexico Caprock down into the Stockton Plateau leading to strong=20 mesoscale cores maintaining a prevalent convective footprint over=20 the Southern Plains.=20 Cell propagation will be east to southeast motions given the=20 850-250mb shear field, entering into fairly unstable environments=20 downstream that will be capable of holding the convective pattern=20 well into the evening. Precipitable water values will be 1+ deviations above season average which could yield hourly rates of 1-2 inches/hour. These types of setups tend to be tricky, but the=20 setup is historically one that favors isolated flash flood=20 concerns, especially within any urbanized areas across the Caprock=20 into the western Red River Basin. The inherited Marginal Risk continued to highlight the region with an elevated threat for heavy rainfall and flash flooding. ....Gulf Coast... Convection will focus along the slow-moving frontal boundary over the Lower Mississippi Valley, particularly across southern Louisiana. Locally heavy rain with cores generally anchored to any remnants of the front as it decays within the southern Parishes of the state. Several CAMs indicated a heavy rainfall footprint from the Texas/Louisiana border to the New Orleans metro area. The flooding threat is modest at best due to the uncertain nature of=20 where the pulse convective regime will initiate, however the=20 individual totals being depicted via CAMs (5-8") and some global=20 deterministic (3-5") are very much capable of causing some flash=20 flood concerns across the area. A Marginal Risk remains in effect for this portion of the state, with only minor reshaping from the previous issuance. Campbell/Kleebauer Day 2 Valid 12Z Wed Apr 23 2025 - 12Z Thu Apr 24 2025 ....THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF THE CENTRAL AND SOUTHERN PLAINS... Several shortwaves will be exiting the Rockies throughout the day=20 with several pockets of convective development sprawled across the=20 Central and Southern High Plains by the evening hours. While the confidence continues to be lower on the maximum amounts there is however higher confidence on the potential for scattered flash=20 flood prospects. Although the location of QPF maxima vary, there=20 is a general consensus of a widespread 1 to 2 inches from the Front Range of Colorado/Wyoming/Nebraska south to the Red River Basin=20 near Texas to Kansas/Oklahoma. Some of these areas will have seen=20 significant rainfall prior to any additional impacts leading to=20 some localized lower FFG indices once the event occurs. The=20 inherited Marginal continued to mostly highlight areas across the=20 Plains that had an elevated threat for heavy rainfall and flash=20 flooding. The latest guidance and WPC QPF trended higher with QPF=20 over northeast Kansas, southern Nebraska, southwest Iowa and=20 northwest Missouri. As such, the Marginal Risk area was modified to encompass that part of the region. Campbell/Kleebauer Day 3 Valid 12Z Thu Apr 24 2025 - 12Z Fri Apr 25 2025 ....THERE IS A SLIGHT RISK FOR EXCESSIVE RAINFALL FOR PORTIONS OF KANSAS, OKLAHOMA, ARKANSAS AND MISSOURI...=20 The pattern will be favorable for multiple rounds of showers and thunderstorms to move through the south-central U.S. With a moist, unstable flow expected and shortwave energy passing through heavy=20 rainfall will likely develop across the region which may lead to=20 local flash flooding. Areal averages of 1 to 2 inches are forecast with locally higher amounts possible. A Slight Risk for excessive=20 rainfall is in effect for a large portion of Kansas, northern=20 Oklahoma, far northwest Arkansas and western Missouri. A Marginal=20 Risk area spans from northern Texas to southern Nebraska and=20 extreme southwest Iowa. Campbell Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!7DX7Yqu-nxctWKk8_gPbTEg1uajmJjv2fQOHhpt0UiYr= itAqKK-cnJ6QTefXxirrFMK0qK1QqbZ59B_VujwFvKjsX_k$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!7DX7Yqu-nxctWKk8_gPbTEg1uajmJjv2fQOHhpt0UiYr= itAqKK-cnJ6QTefXxirrFMK0qK1QqbZ59B_VujwFPv2DpF8$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!7DX7Yqu-nxctWKk8_gPbTEg1uajmJjv2fQOHhpt0UiYr= itAqKK-cnJ6QTefXxirrFMK0qK1QqbZ59B_VujwFkI7fY6E$=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 3.20-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .