Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Nov 26 2024 07:35:39 FOUS30 KWBC 260735 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 235 AM EST Tue Nov 26 2024 Day 1 Valid 12Z Tue Nov 26 2024 - 12Z Wed Nov 27 2024 ....THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF THE SOUTHERN SIERRA NEVADA... A moderately strong atmospheric river will be ongoing this morning across coastal areas of central to southern CA, portions of the=20 San Joaquin Valley and into the southern Sierra Nevada. Please consult MPD #1167 for more details. The axis of subtropical moisture associated with the southern stream upper-level jet will continue to impact the orographically=20 favored high terrain at least through midday, with a gradual=20 thinning out and weakening of the larger scale IVT axis=20 thereafter. The 00Z HREF guidance suggests weaker forcing overall,=20 with more modest ascent by later in the day and this will lead to a dampening of the rainfall rates and coverage of rain with time.=20 Nevertheless, some 0.25" to 0.50"/hour rainfall rates at least=20 through this morning should facilitate additional rainfall amounts=20 as high as 2 to 4 inches across the foothills of the southern=20 Sierra Nevada. Lesser amounts will be noted over the coastal ranges and into areas of the San Joaquin Valley. Given the wet antecedent conditions, these additional rains are expected to extend the=20 threat for some areas of flooding, and potentially a localized burn scar flash flooding impact going through the morning hours.=20 However, conditions should improve during the afternoon as the=20 atmospheric river itself weakens substantially and the rainfall=20 rates diminish. The Slight Risk area is maintained for the=20 foothills of the southern Sierra Nevada with just some modest=20 tweaks made to the Marginal Risk area involving the San Joaquin=20 Valley and the coastal ranges. Orrison Day 2 Valid 12Z Wed Nov 27 2024 - 12Z Thu Nov 28 2024 The probability of rainfall exceeding flash flood guidance is less than 5 percent. Orrison Day 3 Valid 12Z Thu Nov 28 2024 - 12Z Fri Nov 29 2024 The probability of rainfall exceeding flash flood guidance is less than 5 percent. Orrison Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!9Y5CVZ9mEFI8BMgUNw8zXLm-HgMpXhUMxEo9pubpHErV= tKZX6T_v1DyiD4CU_L410b-CtSSYpwWhXlcCPzN_LrmjnrI$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!9Y5CVZ9mEFI8BMgUNw8zXLm-HgMpXhUMxEo9pubpHErV= tKZX6T_v1DyiD4CU_L410b-CtSSYpwWhXlcCPzN_6C5d4oU$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!9Y5CVZ9mEFI8BMgUNw8zXLm-HgMpXhUMxEo9pubpHErV= tKZX6T_v1DyiD4CU_L410b-CtSSYpwWhXlcCPzN_p5vX0LM$=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) .