Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Apr 20 2023 08:38:31 FOUS30 KWBC 200838 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 437 AM EDT Thu Apr 20 2023 Day 1 Valid 12Z Thu Apr 20 2023 - 12Z Fri Apr 21 2023 ......THERE IS A SLIGHT RISK FOR EXCESSIVE RAINFALL FOR PORTIONS OF EAST TEXAS TO THE MID-SOUTH... Deep-layer Gulf moisture streams up across Texas until a cold frontal passage early Friday. PW values of 1.75 inches (1.5 to 2 sigma) will spread over central/eastern Texas through Arkansas and the Mid-South by Thursday afternoon ahead of the frontal boundary as it approaches. As the front approaches, the southwesterly flow will then align nearly parallel which will increase the potential for repeating and backbuilding storms. The latest global guidance depicts 1 to 4 inches spanning eastern Texas/Gulf Coast to mid-Mississippi Valley with some of the hi-res suggesting embedded maximums of 5 to 7 inches possible from eastern Texas to the central Arkansas. There is a growing signal for several inches to fall over far southeast Texas/southwest Louisiana therefore the Slight Risk area was expanded to the Gulf Coast to account for this trend. Further north, amounts around 1 inch or less is expected north of the mid-Mississippi Valley; though FFG will remain lower there due to recent rains (and snowmelt in WI), there will be an elevated threat for flooding concerns. Campbell Day 2 Valid 12Z Fri Apr 21 2023 - 12Z Sat Apr 22 2023 ....THERE IS A SLIGHT RISK FOR EXCESSIVE RAINFALL FROM THE LOUISIANA COAST THROUGH THE MID-SOUTH... Pre-frontal convection across portions of eastern Texas and Louisiana will be continue to track over some of the same locations from the previous day. This part of the region will have much lower FFG in response thus elevating the risk for excessive rainfall for this period. Meanwhile deep Gulf moisture will continue to be drawn northward to fuel showers and thunderstorms with the strongest moisture convergences aligning from southern Louisiana to western Tennessee with perhaps the best repeating threats along the western Gulf Coast early Friday and near the Mississippi Delta later in the day. The Slight Risk area was broadened a little west-east across the Gulf Coast, as well as, nudging northward into southern Kentucky. The latest guidance shows a small reduction in the QPF across the Great Lakes/Ohio Valley, so the Marginal Risk was trimmed southward to the Michigan/Ohio border. Campbell Day 3 Valid 12Z Sat Apr 22 2023 - 12Z Sun Apr 23 2023 ....THERE IS A MARGINAL RISK FOR EXCESSIVE RAINFALL FOR PORTIONS OF THE MID-ATLANTIC... Although there is a fair amount of spread on where and how much rain will fall there was a notable trend for the highest QPF to be in the proximity of I-95 and points east in central/southeast portions of Virginia and North Carolina in addition to reducing amounts along the I-81 corridor and the adjacent mountains. This prompted a reduction areal coverage of the Marginal Risk area by nearly half. While the FFGs are lower across the western area, the progressive nature and lower QPF forecast may limit the realization of flooding. The best potential for impactful rain and flooding concerns will be near the Richmond metro and surrounding locations. Much of eastern North Carolina/Southeast Virginia should be able to handle 1 to 2 inches over the course of 24 hours will minimal/no flooding concerns. If newer guidance continues to favor faster/drier trends, there may be the need to remove the Marginal Risk. Campbell Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!9aak_pGxSfW9hwpV7jcSNNhsp3_qqMcgZDap41pmr7wq= iUJclyGWUDEWODFjwtMqzQXf5yOS8v7X13MlKeok6QrTEMs$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!9aak_pGxSfW9hwpV7jcSNNhsp3_qqMcgZDap41pmr7wq= iUJclyGWUDEWODFjwtMqzQXf5yOS8v7X13MlKeok3plEsnY$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!9aak_pGxSfW9hwpV7jcSNNhsp3_qqMcgZDap41pmr7wq= iUJclyGWUDEWODFjwtMqzQXf5yOS8v7X13MlKeokeGr-dZg$=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) .