Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Oct 22 2025 14:51:06 FOUS30 KWBC 221450 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 1050 AM EDT Wed Oct 22 2025 Day 1 Valid 16Z Wed Oct 22 2025 - 12Z Thu Oct 23 2025 ....16Z Update... The probability of rainfall exceeding flash flood guidance is less than 5 percent. Wegman Day 2 Valid 12Z Thu Oct 23 2025 - 12Z Fri Oct 24 2025 The probability of rainfall exceeding flash flood guidance is less than 5 percent. Hurley Day 3 Valid 12Z Fri Oct 24 2025 - 12Z Sat Oct 25 2025 ....THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE SOUTHERN PLAINS INTO THE WESTERN OZARKS... ....Southern Plains into the Western Ozarks... Models continue to amplify the mid/upper trough across the southern Rockies-southern High Plains Sat-Sat night as a subtropical jet streak rounds the trough base. Meanwhile, the northern stream jet streak begins to curve across the central Plains-Mid MS Valley, which within a broad right entrance region, would couple with the increasing southern stream forcing and thus lead to a fairly sizable area of robust deep-layer lift and low-level moisture transport. TPWs climb between 1.5 to 2.0" from north-south across the outlook areas. which is around 2 standard deviations above normal for late Oct. Meanwhile, increasing south-southwesterly low level flow (35-40+ kts at 850 mb) will begin to align with while reach the same magnitude of the mean 850-300 mb flow during the period, as the upper trough amplifies and approaching surface front slows down. This will favor a higher likelihood of multiple linear convective segments ahead of the front, with cell training most likely within the Slight Risk area. Guidance shows pockets of 3-6+ inches of rain within the Slight Risk area, particularly across North TX into central-northeast OK. There is still some areal-spread however with respect to the heaviest totals. Given this along with the the dry antecedent conditions (low soil moisture percentiles from NASA SPoRT and high FFG values from the RFCs), for now at least have not considered an upgrade to a Moderate Risk. ....Pacific Northwest into Northwest California... The Marginal Risk area from yesterday's Day 4 ERO was modified only slightly for today's Day 3 ERO. Modest Atmospheric River (AR), level 3 on a 5-level scale per the Center for Western Weather and Water Extremes (CW3E), will push across the coastal and Cascade ranges over WA/OR Friday, then into the northwest CA coastal and Shasta/Siskiyous late Fri and Friday night. IVT values peak around 700-750 Kg/m/s, however only for a brief period of time at any given location as the AR is rather transient (steady southward progression). Guidance is in fairly good agreement with the QPF amounts, averaging 2-4" across the outlook area, with local totals of 5+ inches. Much of this would fall within 12 hours as the AR traverses the area, with peak rates near 0.50"/hr along and near the axis of maximum TPW (1.00-1.25") with some (albeit weak) elevated instability (MUCAPEs ~100-200 J/Kg). This rainfall may induce some localized short-term runoff issues, particularly in more urban/poor drainage areas and over burn scars. Hurley Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!_orZQZIkzVX2f8tIiKs15GcIs_EZPAM43oI2YNlaLQ55= TNTI2ePzo9Yx2cwOZmVAm5MvxHQIFP32JpgiMDE8PPmeWCI$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!_orZQZIkzVX2f8tIiKs15GcIs_EZPAM43oI2YNlaLQ55= TNTI2ePzo9Yx2cwOZmVAm5MvxHQIFP32JpgiMDE8WVlDeLM$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!_orZQZIkzVX2f8tIiKs15GcIs_EZPAM43oI2YNlaLQ55= TNTI2ePzo9Yx2cwOZmVAm5MvxHQIFP32JpgiMDE8zbWzX4I$=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) .