Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri Nov 07 2025 00:21:39 FOUS30 KWBC 070021 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 721 PM EST Thu Nov 6 2025 Day 1 Valid 01Z Fri Nov 07 2025 - 12Z Fri Nov 07 2025 ....THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF NORTHWESTERN CALIFORNIA AND FAR SOUTHWESTERN OREGON, AS WELL AS THE OLYMPIC MOUNTAINS AND ADJACENT PORTIONS OF COASTAL NORTHWEST WASHINGTON... 12Z guidance and the 18Z suite of probability guidance remained on track for placement/timing of the next surge of enhanced rainfall...and supported by trends in the short term radar and satellite imagery. 21Z surface analysis showed a sub-990mb low=20 pressure translating quickly through the Southeast Gulf of Alaska=20 toward northern British Columbia with triple point about ready to=20 press into western Washington. The amplification of the warm sector will allow for a quick surge of enhanced moisture flux from the=20 southwest into the Olympic Range with IVT peaking near 700-800=20 kg/m/s...bringing the bulk of highest rates across the areas solid=20 potential of up to .5"/hr rates for a couple more hours. Potential=20 rainfall totals remain in the 2 inch to 4 inch range. Given upper=20 soil conditions (0-40cm per NASA SPoRT) are nearing 90%, much of=20 that rainfall can run off and that results in localized flooding=20 concerns within typical river basins. Farther south, peak IVT values are expected in the 500 to 600 kg/m/s range as the front continues to push eastward into portions of northwestern California and southwestern Oregon. The peak IVT and associated enhanced rainfall rate should be fairly short- lived...on the order of a few hours or so...before the deep layer flow becomes more zonal which allows for increased duration of=20 light to moderate rainfall. Additional 1 inch to 2 inch amounts are possible...and the soils are saturating resulting in increased=20 runoff. No fundamental adjustments were needed to either of the two=20 Marginal Risk areas given the expected flow patterns into the=20 terrain. Bann Day 2 Valid 12Z Fri Nov 07 2025 - 12Z Sat Nov 08 2025 The probability of rainfall exceeding flash flood guidance is less than 5 percent. Hurley Day 3 Valid 12Z Sat Nov 08 2025 - 12Z Sun Nov 09 2025 The probability of rainfall exceeding flash flood guidance is less than 5 percent. Hurley Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/94epoints.txt= __;!!DZ3fjg!8bUS6Ir4CeEO-mWTLAhy5HWhhBIaBs_IUBL5DHehuBHHgoa2ObQlYL9AAL4VOoS= EQuCmoo7EdoivJHb8RPY-OW9rrMI$ Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/98epoints.txt= __;!!DZ3fjg!8bUS6Ir4CeEO-mWTLAhy5HWhhBIaBs_IUBL5DHehuBHHgoa2ObQlYL9AAL4VOoS= EQuCmoo7EdoivJHb8RPY-FBHPS4I$ Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/99epoints.txt= __;!!DZ3fjg!8bUS6Ir4CeEO-mWTLAhy5HWhhBIaBs_IUBL5DHehuBHHgoa2ObQlYL9AAL4VOoS= EQuCmoo7EdoivJHb8RPY-pNI47CY$=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) .