Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Feb 09 2025 01:00:23 FOUS30 KWBC 090100 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 800 PM EST Sat Feb 8 2025 Day 1 Valid 01Z Sun Feb 09 2025 - 12Z Sun Feb 09 2025 ....THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF=20 WEST VIRGINIA... 01Z Update... Given the antecedent soil conditions and ongoing flooding issues,=20 a Marginal Risk was left in place across portions of eastern and southern West Virginia. Radar shows showers developing along and=20 ahead of a cold front, including a narrow line of more intense=20 showers developing along the front as it advances across central=20 Kentucky this hour. These showers are advancing quickly to the=20 east, keeping accumulations in check, however sufficient moisture=20 and forcing, along with modest instability are supporting rainfall=20 rates up to 0.5 in/hr within some of the more intense showers.=20 These showers are expected to reach eastern West Virginia later=20 this evening, around 03-04Z. While the consensus of the hi-res=20 guidance indicates most areas will receive under 0.5 inch, 3-hr=20 FFGs are as low as 0.25 inch -- indicating even a brief period of=20 heavy rainfall may exacerbate existing flooding issues over the=20 area.=20 Pereira ....Previous Discussion... Strong N-S quasi-zonal mid and upper level flow will be perturbed=20 a bit during Day 1 (12Z Sat-12Z Sun) as a 150+ kt upper level jet=20 streak traverses the Upper Midwest and Ohio Valley, while a flat=20 500 mb vort lobe pushes across the Lower Great Lakes. Broad-scale=20 exit region forcing associated with the upper jet axis will surge=20 southwesterly low-level inflow ahead of the surface frontal wave,=20 with 850 mb moisture flux anomalies peaking between 4-5 standard=20 deviations above normal later this afternoon into Sat night, while=20 TPW values peak around 1". Robust synoptic-scale support and low-=20 level moisture transport will be offset somewhat by the weak=20 elevated instability, with MUCAPEs generally less than 500 J/Kg.=20 Nevertheless, even though not advertised on the latest (00Z Sat)=20 HREF, the aforementioned dynamic and thermodynamic ingredients will be sufficient for spotty hourly rain rates of 0.5"+ and 3-hourly=20 rates of 1.0"+, with localized event totals between 1.5-2.0"+. Current 3-hr flash flood guidance values remain quite low (1" or less) across the outlook area, which includes much of WV. Despite the lack of instability, the low FFG values could be exceeded over isolated areas with 2 consecutive hours of 0.5"+/hr rainfall rates. Since the soils in these areas are saturated, and the terrain is rugged, we have maintained the Marginal Risk area for much of WV (outside of its northern or eastern Panhandles). Hurley/Roth Day 2 Valid 12Z Sun Feb 09 2025 - 12Z Mon Feb 10 2025 The probability of rainfall exceeding flash flood guidance is less than 5 percent. Pereira Day 3 Valid 12Z Mon Feb 10 2025 - 12Z Tue Feb 11 2025 The probability of rainfall exceeding flash flood guidance is less than 5 percent. Pereira Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!_GipmyKKkcctlkl3Bq266nAQpCvgKz1z571JOXrpFZA6= XQWiqjm38nYL_dLvhOQrRmSdKBj8aVhke9yImNu9ENeXvgw$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!_GipmyKKkcctlkl3Bq266nAQpCvgKz1z571JOXrpFZA6= XQWiqjm38nYL_dLvhOQrRmSdKBj8aVhke9yImNu9ezXCBXE$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!_GipmyKKkcctlkl3Bq266nAQpCvgKz1z571JOXrpFZA6= XQWiqjm38nYL_dLvhOQrRmSdKBj8aVhke9yImNu9j5ZDTqI$=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) .