Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Feb 04 2024 08:17:20 FOUS30 KWBC 040817 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 316 AM EST Sun Feb 04 2024 Day 1 Valid 12Z Sun Feb 04 2024 - 12Z Mon Feb 05 2024 ....THERE IS A HIGH RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF SOUTHERN CALIFORNIA... ....Central to Southern California... The deepening low off the Central to Northern California coast will continue to strengthen the Atmospheric River event into large portions of Central to Southern California day 1. The strongest IVT...600 to 800+ kg/m/s will be impacting the Central California coast range, south into the Transverse Range and inland into northern portions of the San Joaquin Valley and Sacramento Valley during the first half of day 1, with decreasing IVT during the second half. Models remain consistent in showing widespread heavy totals from the northern portions of the Peninsular Range through the Transverse Range and northward along the Central California Coast Range. A high risk was maintained through the Transverse Range where the best upslope component will occur. Changes to the previous outlook were to extend the high risk area farther to the east into the eastern portions of the Transverse Range where the upslope flow lingers longer than areas farther the west. The high risk was also expanded south to cover all of Los Angeles county to the south of the Transverse Range as per coordination with WFO LOX. Life threatening flash and urban flash flooding possible in the high risk area. Areal average day 1 precip totals of 3-5" likely from the Central CA Coast Range south into the Transverse Range, with isolated 6-10" totals in the best upslope areas of the Transverse and Central California Coast Range. The high risk area fit well where the HREF neighborhood probabilities are high for 3" and 5"+ totals day 1. HREF neighborhood probabilities are also showing a fairly large 40-60% probabilities for 8"+ totals across central portions of the Transverse Range.=20 ....Southeast, eastern Gulf Coast and Florida... The broad upper vortex over the Lower Mississippi Valley will be sinking slowly southeastward into the northeast Gulf of Mexico day 1. The previous marginal risk area on the north and northeast side of this vortex was narrowed by approximately 50-75 miles to better match where the latest HREF hourly probabilities are high for .50"+/hr amounts. This will be during the period of strengthening southeasterly low level flow ahead of compact surface wave rotating northeastward off the northeast Gulf and into the Florida Panhandle. Heaviest totals ahead of this low likely along the GA/Lower SC coast where the low level onshore east southeasterly flow persists the longest day 1 and corresponds to the area of most defined boundary layer convergence.=20 On the south side of the northeast Gulf vortex, a more defined area of instability and associated organized convection may push eastward into Southwest Florida early day 1, reaching the east central to southeast coast of FL by late morning/early afternoon.=20 This convection will be very fast moving but still may produce totals of .50-1"+ in an hour, resulting in potential for isolated urban issues both on the Southwest coast and Southeast coast. A marginal risk was re-introduced for the urban areas on the southeast coast and maintained for the urban areas of Southwest Florida. Oravec 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!_8_atTJqN_7fY-iB_LeJZAaHOJ55bQino2aUCt7sNthd= ssG7_cERYUHfenSHWpi7lKigERZWF_YY__eZhmQIrUsAdgM$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!_8_atTJqN_7fY-iB_LeJZAaHOJ55bQino2aUCt7sNthd= ssG7_cERYUHfenSHWpi7lKigERZWF_YY__eZhmQIPBmg7RA$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!_8_atTJqN_7fY-iB_LeJZAaHOJ55bQino2aUCt7sNthd= ssG7_cERYUHfenSHWpi7lKigERZWF_YY__eZhmQI7A0BBEg$=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) .