Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sat Nov 05 2022 15:55:22 FOUS30 KWBC 051555 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 1154 AM EDT Sat Nov 05 2022 Day 1 Valid 16Z Sat Nov 05 2022 - 12Z Sun Nov 06 2022 The probability of rainfall exceeding flash flood guidance is less than 5 percent. ....Central Gulf Coast... A long-lived line of pre-frontal showers and thunderstorms continues to advance gradually off to the east across the Gulf Coast states as a deep layer trough continues to pivot northeastward across the Midwest. In time heading through the afternoon hours, the stronger upper support that was helping to sustain the convective threat from overnight and through this morning will begin to pull away and become detached from any conducive downstream thermodynamic environment for sustainable convection. The airmass downstream out ahead of the current activity is quite stable and this should favor a continued weakening trend of the shower and thunderstorm activity over the next several hours. These is a very modest nose of weak instability still lurking near southern MS and southern AL, and the 12Z HREF guidance suggests perhaps enough convective vigor for some spotty 1 to 2 inch rainfall amounts going through mid-afternoon across these areas and mainly along the immediate coast. Aside from some highly isolated urban runoff considerations in the near-term, flash flooding is not expected. Thus, the Marginal Risk area has been dropped with this update. Orrison Day 2 Valid 12Z Sun Nov 06 2022 - 12Z Mon Nov 07 2022 ....THERE IS A MARGINAL RISK FOR EXCESSIVE RAINFALL ACROSS COASTAL OREGON AND NORTHWESTERN CALIFORNIA... No changes were made to the inherited Marginal Risk area for portions of the coastal Pacific Northwest. A vertically stacked low sliding down the coast will bring another round of heavy rainfall to coastal OR and northwest CA on Sunday. The rainfall will be supported by a very active shortwave moving across the region in the upper levels, as an upper level low digs southward down the coast. Further, cold air associated with the trough moving in behind a leading cold front will draw a large thermal gradient across the front, supporting greater low level lift. Since these areas have been catching the tail-end weakening phase of the atmospheric rivers hitting areas harder further north, this area should be able to handle the 1-3" of rain expected on Sunday, despite the recent wetter conditions. Snow levels will be dropping from 3,500 ft early in the day to near 2,000 feet Sunday night. The Marginal Risk was maintained for the coast and coastal ranges where isolated flooding issues may develop with this next atmospheric river event. Wegman/Taylor Day 3 Valid 12Z Mon Nov 07 2022 - 12Z Tue Nov 08 2022 The probability of rainfall exceeding flash flood guidance is less than 5 percent. Wegman Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!6DTww2ymJjG5xgsgUOD0xLLl1fuWQZ1WkpM-ixqRqKbv= SIEtIKquSivbkAf8BCMif1sBODg8TA37wRhD0fHXjzLXlGo$=20=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!6DTww2ymJjG5xgsgUOD0xLLl1fuWQZ1WkpM-ixqRqKbv= SIEtIKquSivbkAf8BCMif1sBODg8TA37wRhD0fHXuvc1NSE$=20=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!6DTww2ymJjG5xgsgUOD0xLLl1fuWQZ1WkpM-ixqRqKbv= SIEtIKquSivbkAf8BCMif1sBODg8TA37wRhD0fHX_4IKU0A$=20=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 3.14-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .