Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Mon Feb 10 2025 00:45:33 FOUS30 KWBC 100045 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 745 PM EST Sun Feb 9 2025 Day 1 Valid 01Z Mon Feb 10 2025 - 12Z Mon Feb 10 2025 The probability of rainfall exceeding flash flood guidance is less than 5 percent. Pereira Day 2 Valid 12Z Mon Feb 10 2025 - 12Z Tue Feb 11 2025 The probability of rainfall exceeding flash flood guidance is less than 5 percent. Oravec Day 3 Valid 12Z Tue Feb 11 2025 - 12Z Wed Feb 12 2025 ....THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FROM PORTIONS OF THE MID-SOUTH AND LOWER MISSISSIPPI VALLEY INTO THE TENNESSEE VALLEY... ....ArkLaTex-ArkLaMis into the Mid-South and Tennessee Valley... Strong NW-SE upper level jet streak will dive southeast into CA late on Day 3 (Tue night) -- on the western periphery of the longwave trough towards the base. As this occurs, the broad western U.S. trough will amplify, thereby enhancing the deep-layer ascent and southwesterly flow/moisture transport within a maturing Warm Conveyor Belt (WCB) downstream across the Mid South-Lower MS Valley and TN Valley. 850-700 mb moisture flux anomalies increase to 2-3 standard deviations above normal Tue-Tue night, while TPW values climb to 1.5-1.75" (around +2 standard deviation above normal). The strengthening dynamical and thermodynamical support will make for efficient rainfall rates despite the lack of deep-layer instability. Much of the guidance, non-CAM at this point being a Day 3 forecast, depicts a widespread swath of 1.5-2.5" of rain within the outlook areas, with more stripes of >3" within the Slight Risk area. Storm motions nearly parallel to the WSW-ENE oriented surface boundary will boost the potential for training, and even though currently the non-CAM guidance is advertising meager deep-layer elevated instability (MUCAPEs generally 250-500 J/Kg), believe these values will be amplified somewhat as the event gets within the high-res CAM windows, again given the dynamic and thermodynamic response to the broad-scale upper trough amplification. 2.00"+/3hr rainfall rates are anticipated where the cells do train, again most likely within the Slight Risk area, which could lead to localized-scattered instances of flash flooding. Hurley 2100 UTC update: At the moment, no significant changes made to the previous outlook areas. The 12Z model suite is fairly consistent with the previous guidance. Oravec Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/94epoints.txt= __;!!DZ3fjg!9qUzcD1EhKtHB2tCSA8FoG2MrqSfo1Gm8_HO9QV95vbZ8mNqtBCil6M_gk6hlce= 8xa-_QJSrRjsusADZU8gpmmuA58s$ Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/98epoints.txt= __;!!DZ3fjg!9qUzcD1EhKtHB2tCSA8FoG2MrqSfo1Gm8_HO9QV95vbZ8mNqtBCil6M_gk6hlce= 8xa-_QJSrRjsusADZU8gpfv-6nXo$ Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/qpf/99epoints.txt= __;!!DZ3fjg!9qUzcD1EhKtHB2tCSA8FoG2MrqSfo1Gm8_HO9QV95vbZ8mNqtBCil6M_gk6hlce= 8xa-_QJSrRjsusADZU8gpaHrRbCk$=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 3.20-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .