Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Mar 19 2023 08:02:59 FOUS30 KWBC 190802 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 402 AM EDT Sun Mar 19 2023 Day 1 Valid 12Z Sun Mar 19 2023 - 12Z Mon Mar 20 2023 The probability of rainfall exceeding flash flood guidance is less than 5 percent. Oravec Day 2 Valid 12Z Mon Mar 20 2023 - 12Z Tue Mar 21 2023 The probability of rainfall exceeding flash flood guidance is less than 5 percent. Oravec Day 3 Valid 12Z Tue Mar 21 2023 - 12Z Wed Mar 22 2023 ....THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS COASTAL AREAS OF SOUTHERN CALIFORNIA AND CENTRAL ARIZONA... The latest model guidance is in good agreement with a strong closed low diving southeast day 2 across the Northeast Pacific and inland into central California and the Great Basin on day 3.=20 Strong 850 to 700 mb moisture flux expected on the south side of this closed low, impacting areas from the central California coast range , southeast through the Transverse and Peninsular Ranges and into the southern Sierra during the day on Tuesday, spreading inland into the Southwest Tuesday night into early Wednesday. The National Water Model streamflow anomaly map continues to show high flows to most of the streams across the central California coast range, southeast into coastal southern California, including the Transverse and Peninsular Ranges, which coincides with anomalous soil moisture values as per NASA SPoRT maps. There is fairly good model agreement on heavy precipitation potential across the slight risk areas of California, with widespread 1.25 - 2.5"+ values. Given this the previous marginal risk area across these regions was upgraded to slight. No changes made to the marginal risk area over the southern to central Valley/foothills of the Sierra with the heaviest precip here expected to fall as snow in the Sierra, with no significant contribution to runoff from snow melt expected.=20 Inland across central Arizona, the previous marginal risk areas was also upgraded to slight. 850-700 mb moisture flux values expected to become very anomalous late Tuesday into early Wednesday, 4 to 5 standard deviations above the mean, over the Southwest as the strong upper trof moves inland from Central California into the Great Basin. Snow level expected to be high with much of the precip into the Mogollon Rim area falling as rain. Stream flow and soil moisture anomalies are not as great across central AZ as points farther west across California, with values at or slightly above normal. However, given the strong south southwesterly upslope flow into the Mogollon Rim region and resultant heavy precip potential, model consensus 1 to 2"+ areal average totals, an upgrade to slight risk was warranted. Oravec Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!_7vkd0s4nJfQ5W3v-MgUwACLWKTlk73wxuCyYqXcQxv5= dJvbTOMA3Yzp-p68MHzTvfu6F8LLLnGx2gEU3nI07rwVOvI$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!_7vkd0s4nJfQ5W3v-MgUwACLWKTlk73wxuCyYqXcQxv5= dJvbTOMA3Yzp-p68MHzTvfu6F8LLLnGx2gEU3nI0tf86ULs$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!_7vkd0s4nJfQ5W3v-MgUwACLWKTlk73wxuCyYqXcQxv5= dJvbTOMA3Yzp-p68MHzTvfu6F8LLLnGx2gEU3nI0v-cC6yA$=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) .