Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Jan 07 2025 07:33:05 FOUS30 KWBC 070732 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 232 AM EST Tue Jan 7 2025 Day 1 Valid 12Z Tue Jan 07 2025 - 12Z Wed Jan 08 2025 The probability of rainfall exceeding flash flood guidance is less than 5 percent. Kleebauer Day 2 Valid 12Z Wed Jan 08 2025 - 12Z Thu Jan 09 2025 The probability of rainfall exceeding flash flood guidance is less than 5 percent. Kleebauer Day 3 Valid 12Z Thu Jan 09 2025 - 12Z Fri Jan 10 2025 Highly anomalous upper trough pattern across the Western CONUS will help generate a distinct shortwave ejection evolution that will=20 create a litany of issues across TX into the Lower Mississippi=20 Valley. Upper low expected to be centered over Sonora the prior period will open as it advances eastward with a second shortwave digging around the backside of the mean trough creating a fairly dynamic setup across the Southern Plains. A strong diffluent axis=20 of ascent ahead of the ejecting trough will create a blossoming of=20 precipitation over TX, spreading eastward as the trough migrates=20 through the Lone Star State. Surface low pressure will spawn in-of=20 the western Gulf with the low center generally close to the TX=20 coastal plain, opening the door for a modest instability gradient=20 to align within the immediate TX coast up to southwest LA as the=20 pattern progresses. Convective regime will be most prominent along=20 the coast where forecast theta_E's will slowly climb just above=20 seasonal norms allowing for a focused area of surface instability=20 along with the already favorable mid and upper level dynamics.=20 A cluster of thunderstorms will likely form over the western Gulf=20 within the confines of the surface reflection lending a better=20 potential for convection to move inland with a heavy rain footprint tied to any storm moving onshore. There will be a sharp northern=20 extent of how long any convective regime can last as much colder to the north of the coast will limit surface based instability and=20 thwart the opportunity for convection to march inland. As of now, the forecast MRGL risk inherited from D4 was relatively maintained, although the northern periphery was trimmed back given the lackluster instability fields and relatively progressive storm motion on the northern fringe of the best instability coupled with ascent. The most favorable locations for rates that could generate enough support for flash flooding potential is still relegated to the immediate Gulf coast with a small buffer further inland if any cells can motion past the immediate coastal plain and affect some of the urban areas extending from CRP up through HOU and LCH.=20 Kleebauer=20 Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!-PnPkRhqhNNkte2gevIL5UjCv60ajK0sYXlolXF_OyR_= rjrmS-B9iOOZWbIIfi1H9nKpBDYhXGwyx-eAm67frhUHm7Q$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!-PnPkRhqhNNkte2gevIL5UjCv60ajK0sYXlolXF_OyR_= rjrmS-B9iOOZWbIIfi1H9nKpBDYhXGwyx-eAm67fylgaSqM$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!-PnPkRhqhNNkte2gevIL5UjCv60ajK0sYXlolXF_OyR_= rjrmS-B9iOOZWbIIfi1H9nKpBDYhXGwyx-eAm67frrt2lb8$=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) .