Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sat Nov 26 2022 08:07:03 FOUS30 KWBC 260806 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 306 AM EST Sat Nov 26 2022 Day 1 Valid 12Z Sat Nov 26 2022 - 12Z Sun Nov 27 2022 ....THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS MUCH OF LOUISIANA AND EASTERN TEXAS... Ongoing heavy rainfall this morning across eastern Texas will continue to pose a flash flood risk, particularly along the mid to upper Texas coast this morning. The closed upper low over west Texas will slowly move east, with its very strong area of upper divergence positioned over the region. Over the last few hours, this strengthening forcing for ascent combined with the increasing low level inflow has led to an uptick in convective coverage and intensity over the last couple of hours. The most recent analysis showed upward of 1.75"+ precipitable water values along the coast and an increasing axis of instability brushing the coast. The expectation for today is that the axis of moderate to locally heavy rainfall will begin to shift eastward as the upper low lifts northeast and an advancing cold front passes through. Ahead of that frontal passage, the combination of much above normal PWs (2-3 standard deviations above normal) and sufficient instability (recent guidance suggesting upwards of 500 to 1000 J/kg MUCAPE along the coast) should allow for localized intense rain rates to develop at times as the clusters of moderate to heavier thunderstorms move eastward across much of Louisiana. The 00Z HREF probabilities support isolated 1-2" hourly totals with an isolated signal showing up for 3" totals in 6-hrs. The greatest rainfall areas look to be across the upper Texas coast through portions of southeastern Louisiana. Here, the Slight Risk inherited was largely unchanged with some minor adjustments made to the latest trends. Portions of the area received heavy rainfall recently (broad 2-4" with localized 4-5"+) and therefore has much greater soil saturation. Recent NASA SPoRT product shows the 0-40 cm layer saturation to be above 80-90 percent in places, so this additional rainfall may lead to faster runoff and potential flash flooding, particularly for urban and other sensitive/vulnerable locations. Later tonight into early Sunday morning, convection could uptick and stall over portions of the western Florida panhandle as recent hi-res models depict the frontal passage slowing down as the main synoptic features lift into the lower Great Lakes. Meanwhile, very strong 850 mb inflow moving onshore will bring upwards of 1.75" to near 2" PWs onshore. This could allow for some isolated training of heavier thunderstorms. For now, the Marginal Risk wasn't changed too much over this region, but something to watch in the update later this morning for a possible localized greater threat for flash flooding. Taylor 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!41q6cm2R5vIND_Xp7dYrWwQykQAfJ5pHW6tGOUjK7rDr= kommnyA984jjTbpGSHlKwwRBsvWWoc4fhxnfbph2GPRlpEU$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!41q6cm2R5vIND_Xp7dYrWwQykQAfJ5pHW6tGOUjK7rDr= kommnyA984jjTbpGSHlKwwRBsvWWoc4fhxnfbph2x9yoKRg$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!41q6cm2R5vIND_Xp7dYrWwQykQAfJ5pHW6tGOUjK7rDr= kommnyA984jjTbpGSHlKwwRBsvWWoc4fhxnfbph2XCQckfs$=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) .