Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri Dec 06 2024 09:23:31 FOUS30 KWBC 060923=20=20=20 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 423 AM EST Fri Dec 6 2024 Day 1 Valid 12Z Fri Dec 06 2024 - 12Z Sat Dec 07 2024 The probability of rainfall exceeding flash flood guidance is less than 5 percent. Churchill Day 2 Valid 12Z Sat Dec 07 2024 - 12Z Sun Dec 08 2024 ....THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF EASTERN TEXAS AND WESTERN LOUISIANA... A low-level jet streaming Gulf moisture northward across eastern Texas will interact with a strong shortwave trough which will move northeastward out of New Mexico and into the central Plains. PWATs along the Upper Texas coast are expected to increase to 1.5"+ and instability should remain minimal (and mostly confined to the coast). The heaviest rain is forecast to be on Saturday night due to the typical nocturnal strengthening of the low-level jet. Soils have become a bit more saturated in this region due to the recent rainfall, and some rainfall is expected on Friday. Isolated flash flooding is possible, especially in areas of more saturated soils, urban areas, and flood prone/low lying areas. Churchill/Roth Day 3 Valid 12Z Sun Dec 08 2024 - 12Z Mon Dec 09 2024 ....THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE LOWER MISSISSIPPI VALLEY AND CENTRAL GULF COAST... Continued moisture flux transport via a moderately strong low- level jet is expected to result in increasing coverage of flash flooding on Sunday, as the bulk of the forcing and jet dynamics via the aforementioned strong shortwave trough will not arrive until midday (along with maximized instability). Localized training is expected to result in 2-4" totals, suggesting a lower-end Slight Risk based on the probability spectrum (which ranges from 15-40%). Given that most of the region is experiencing very dry antecedent soil conditions (10th percentile or lower for much of MS/AR/LA, per NASA SPoRT-LIS 0-100 cm soil moisture), any flooding should be relegated to flood-prone areas (with the greatest risk for any localized significant flash flooding over west-central LA, where antecedent soil conditions and streamflows are locally higher). Churchill Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!4buSaSXkBrhPhQzOyI4o_E9gA-B9Uey-yDaZKVOPfe7T= HwgLLTkeR4IVfhDBz64InUEaJM1lLztwJKTta6pK0dVss28$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!4buSaSXkBrhPhQzOyI4o_E9gA-B9Uey-yDaZKVOPfe7T= HwgLLTkeR4IVfhDBz64InUEaJM1lLztwJKTta6pK8LYQpJA$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!4buSaSXkBrhPhQzOyI4o_E9gA-B9Uey-yDaZKVOPfe7T= HwgLLTkeR4IVfhDBz64InUEaJM1lLztwJKTta6pK0fZTHlw$=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) .