Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Jan 29 2023 07:44:26 FOUS30 KWBC 290744 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 243 AM EST Sun Jan 29 2023 Day 1 Valid 01Z Sun Jan 29 2023 - 12Z Sun Jan 29 2023 ....THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE SOUTHEAST AND CENTRAL GULF COAST... Very few notable changes with this morning's forecast update, based on the latest guidance QPF trends (deterministic and probabilistic). A slowly strengthening upper level jet streak will put much of the Slight Risk area in the right entrance region of the jet streak. Small disturbances riding along the jet may locally trigger convection across the Slight Risk area as they race northeastward with the jet. Much of the dynamics for this rainfall event will be in the lower levels of the atmosphere as broad southerly flow covering the whole of the Gulf peaks in intensity as far as the LLJ is concerned over southern LA midday Sunday. The LLJ will reintensify as the convection moves east across the FL Panhandle and southern GA Sunday night, including values as strong as 60 kt over the FL Panhandle, far SE AL and far SW GA. Thus, expect convection to be quite efficient at producing heavy rainfall as it moves eastward Sunday and Sunday night. To be sure, the greatest threat within the Slight Risk area will be across western areas from TX through MS, with slightly lower threats for flash flooding further east. Peak storm total rainfall may exceed 3 inches in portions of southern LA through southern MS-AL-GA, within a more favorable thermodynamic environment with PWs close to 1.75" along with better deep-layer instability (MUCAPEs 500-1000 J/kg). The 12Z HREF in fact indicates clusters of 40-60+ percent probs of >3"/24hrs within the Slight Risk, with the highest probs (60-80%) just north of the Upper TX Coast through much of southwest LA. There continues to be good model consensus however that the axis of heaviest rain will remain north of New Orleans. Changes with this update were all small tweaks, including dropping a bit more of the Mississippi River Delta south of New Orleans down to a Marginal. There remains a bit of uncertainty as to how far north the convection can get into MS/AL/GA, but with a general very small southward shift, did trim the northern edge of the Slight Risk area through those states a half a county (on average) southward. Wegman/Hurley Day 2 The Day 2 outlook will be updated by 0830Z. Day 3 The Day 3 outlook will be updated by 0830Z. Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!5wH0saYY7maA6ttsGgfjm7Cg2vvQCnsT4td3CAMGwRsP= 6NCX8WsOKnIg8-Lrz8lppR5beLWBlmHeYmb8ZY0gybwfhc0$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!5wH0saYY7maA6ttsGgfjm7Cg2vvQCnsT4td3CAMGwRsP= 6NCX8WsOKnIg8-Lrz8lppR5beLWBlmHeYmb8ZY0gTZOHyX0$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!5wH0saYY7maA6ttsGgfjm7Cg2vvQCnsT4td3CAMGwRsP= 6NCX8WsOKnIg8-Lrz8lppR5beLWBlmHeYmb8ZY0gKX-sFkY$=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) .