Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri Dec 22 2023 08:11:33 FOUS30 KWBC 220811 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 310 AM EST Fri Dec 22 2023 Day 1 Valid 12Z Fri Dec 22 2023 - 12Z Sat Dec 23 2023 ....THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHERN PORTIONS OF CALIFORNIA AND ARIZONA... The deep, closed low centered just offshore southern California/northern Baja early Friday morning will begin to pick up speed as it moves eastward toward central Arizona by early Saturday morning, opening up as it does so. This will put much of southern California, far southern Nevada, and Arizona in a favored region of deep-layer forcing/lift while anomalous S-SSW low-level flow positions a plume of higher moisture initially into southern California then across Arizona during the afternoon/evening hours. Moisture anomalies with this system are expected to remain well above normal, 3 to 4 standard deviations above normal for this time of year for both PW and 850-700 mb moisture flux. PWs in fact are forecast to reach or exceed 1" at times, especially across southwest to south-central Arizona. The GFS and ECMWF IVT forecasts from CW3E show an impressive surge approaching 500+ kg/m/s into central Arizona. During the afternoon, some limited instability may develop across the Desert regions of CA and eastward into southern Arizona, which may allow for some localized higher rain rates approaching 0.50-1.0"/hr at times per the 00Z CAM guidance. Overall, a broad area of 0.75-1.5" totals are expected for the 24-hr period ending 12Z Saturday, with some localized/embedded higher amounts up to 2.5" possible in any thunderstorms. The latest (00Z 12/22) HREF neighborhood probabilities of 24hr QPF exceeding the 2 year ARI are aoa 50 percent for the bulk of the Slight area, with probs of exceeding the 10 year ARI up to 40-60% along the southern CA-AZ border. 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!_HxExL39Ugeat4uY_-IMpU2lIKEaGLQrR5E7vbQywsIh= xy8U4JEcZgWDNTglHf1EOfGocmONrXmMeqPVVApaxIVTbNY$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!_HxExL39Ugeat4uY_-IMpU2lIKEaGLQrR5E7vbQywsIh= xy8U4JEcZgWDNTglHf1EOfGocmONrXmMeqPVVApa4-AAMsA$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!_HxExL39Ugeat4uY_-IMpU2lIKEaGLQrR5E7vbQywsIh= xy8U4JEcZgWDNTglHf1EOfGocmONrXmMeqPVVApaJL4E81I$=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) .