Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Nov 09 2023 20:22:28 FOUS30 KWBC 092022 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 321 PM EST Thu Nov 9 2023 Day 1 Valid 16Z Thu Nov 9 2023 - 12Z Fri Nov 10 2023 ....THERE IS A MARGINAL RISK OF FLOODING FROM THE ARKLATEX TO THE TEXAS GULF COAST... There has been a higher trend in the latest CAM/high res guidance for locally enhanced QPF across portions of the ArkLaTex and also extending south across portions of eastern Texas and the central Texas Gulf Coast. A slow moving cold front is intersecting an anomalously moist airmass across the region, with PWs rising to near 2 inches and surface dewpoints into the lower 70s across southeastern Texas this afternoon. Furthermore, this region will be near the right entrance region of a strong 250 mb jet stream, and this will aid ascent ahead of the front. For the outlook area encompassing southeastern OK, southwestern AR, northeastern TX, and northwestern LA, the heaviest rainfall is expected during the midday hours Thursday followed by a gradual abatement going into the afternoon hours. Although rainfall rates are not expected to be all that high, there may be some instances of elevated convection training across this region that may lead to increased ponding of water and run-off problems, but one of the mitigating factors is the recent dry weather. Farther south near the Texas Gulf Coast, there will be greater instability with a deep nearly saturated layer ahead of the front. The latest HRRR suggests the greatest rainfall rates are expected between 21Z and 6Z tonight, with some hourly rainfall rates on the order of 1-2 inches per hour possible. There may be a few locations that have instances of convective training with 3+ inches of total rainfall possible by 12Z Friday just inland from the coast, and this may also be enough for localized flooding concerns. Therefore, a Marginal Risk area is now valid. Hamrick Day 2 Valid 12Z Fri Nov 10 2023 - 12Z Sat Nov 11 2023 Although there are currently no excessive rainfall risk areas at this time, the models agree that an axis of heavy convection will be just offshore the southern Texas Coast as the cold front and the surface low slowly pushes towards the south. There may be some instances of elevated convection that develops over portions of Deep South Texas, but the majority of the guidance suggests this would not be enough to cause any flooding concerns. However, if the frontal progression slows down and later model runs trend west, then a Marginal Risk area may eventually be needed, so this will continue to be monitored. Elsewhere, the latest CAM guidance indicates the potential for some slow moving storms off the East Coast of Florida over the Gulf Stream waters, but should remain far enough away from land to also keep this region clear of any risk areas for now. Hamrick Day 3 Valid 12Z Sat Nov 11 2023 - 12Z Sun Nov 12 2023 The probability of rainfall exceeding flash flood guidance is less than 5 percent. Hamrick Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!7xGKTLs7MPkv-HFLGHOMF2L_wcvLFOQfv5uCwjqsXpJ6= JU0a6QUduGwTiDHC9S8EI7YtiEtRtksMd1evAuLlQcf9Nhw$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!7xGKTLs7MPkv-HFLGHOMF2L_wcvLFOQfv5uCwjqsXpJ6= JU0a6QUduGwTiDHC9S8EI7YtiEtRtksMd1evAuLlRzuIlTw$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!7xGKTLs7MPkv-HFLGHOMF2L_wcvLFOQfv5uCwjqsXpJ6= JU0a6QUduGwTiDHC9S8EI7YtiEtRtksMd1evAuLlh2etgAY$=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) .