Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri Oct 31 2025 00:56:35 FOUS30 KWBC 310056 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 856 PM EDT Thu Oct 30 2025 Day 1 Valid 01Z Fri Oct 31 2025 - 12Z Fri Oct 31 2025 The probability of rainfall exceeding flash flood guidance is less than 5 percent. Hurley Day 2 Valid 12Z Fri Oct 31 2025 - 12Z Sat Nov 01 2025 ....THERE IS A MARGINAL RISK FOR EXCESSIVE RAINFALL FOR WESTERN WASHINGTON... 2030Z Update... Generally no changes to the previous thinking. The latest guidance continues to support atmospheric river conditions arriving across western WA this period which will drive heavy rainfall into the coastal ranges and the windward slopes of the Cascades. Snow levels will be rather high, some there will be heavier rainfall amounts materializing at some of the higher elevations which as previously mentioned may reach as high as 3 to 5 inches for the period. Made only cosmetic changes to the Marginal Risk area for this update. Orrison Previous discussion... A modestly strong atmospheric river will setup across the Pacific Northwest with an advection of high IVT (>750 Kg/ms) into the region beginning Friday afternoon, carrying through the late evening Friday into Saturday. Inflow at 850 hPa approaches 50 kts out of the southwest while precipitable water values in the coastal ranges rise into the 1.25-1.5" range. MU CAPE is forecast to remain weak, under 250 J/kg. Precip rates should rise to between 0.5-0.75"/hr during the peak of the heavy rainfall, producing local amounts of 3-5" in the higher terrain of western WA, which would be particularly challenging for the Skokomish river. Considering the consistency within guidance on totals and expectation for some enhanced rates to generate river rises and minor flooding, a Marginal Risk was maintained, with some expansion to the south to account for the wetter 00z UKMET solution. Roth Day 3 Valid 12Z Sat Nov 01 2025 - 12Z Sun Nov 02 2025 The probability of rainfall exceeding flash flood guidance is less than 5 percent. Roth/Orrison Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!7zZOUmlxkcFQKn3--BnTH1B1bGK_skqTJVNwXZAZ9p8Z= xF0kUerxK-nlB17fUyV9fZbpzizgfgMibeStStSn_iHmjjY$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!7zZOUmlxkcFQKn3--BnTH1B1bGK_skqTJVNwXZAZ9p8Z= xF0kUerxK-nlB17fUyV9fZbpzizgfgMibeStStSn8MSfiGE$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!7zZOUmlxkcFQKn3--BnTH1B1bGK_skqTJVNwXZAZ9p8Z= xF0kUerxK-nlB17fUyV9fZbpzizgfgMibeStStSnZugAL7A$=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 3.28-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .