BBS: TELESC.NET.BR Assunto: HVYRAIN: Excessive Rainfall Discussion De: COD Weather Processor Data: Wed, 25 Mar 2026 23:50:27 +0000 ----------------------------------------------------------- FOUS30 KWBC 252350 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 750 PM EDT Wed Mar 25 2026 Day 1 Valid 01Z Thu Mar 26 2026 - 12Z Thu Mar 26 2026 The probability of rainfall exceeding flash flood guidance is less than 5 percent. Bann Day 2 Valid 12Z Thu Mar 26 2026 - 12Z Fri Mar 27 2026 ...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE MIDWEST AND UPPER OHIO VALLEY... 2100 UTC update... The 1200 UTC model suite continues to show enhancing convection late Thursday afternoon, continuing Thursday night into early Friday morning, along and ahead of the strong cold front sinking south from the Lower Lakes into the Mid-Atlantic/OH Valley/Mid MS Valley by 1200 UTC Friday. Favorable upper difluence in the right entrance region of the upper jet, in an axis of much above average PW values, 2 to 3+ standard deviations above the mean, along and ahead of this front, will support potential for widespread moderate to heavy precip totals along and ahead of the front. Changes to the previous marginal risk were to expand it northeastward into the Southern Tier of NY State/northern PA where FFG values are lower. Otherwise, models continue to emphasize areas between the Lower Lakes and the OH River for the heaviest totals day 2, but the lower FFG values farther northeast into the Southern Tier of NY State/northern PA, warrant the marginal risk expansion. Overall, the marginal risk area fits well where the HREF and RRFS probabilities for 3 hour precip exceeding 3 hour FFG are the highest. These probabilities are not uniform along and ahead of the front, but do show potential for isolated runoff issues, with areas of probabilities in the 20-40% range. Oravec Previous discussion: Only minor tweaks were needed for the new Day 2 forecast this morning. The latest guidance, including some of the longer-range CAMs, suggests that there is a greater chance for training showers and thunderstorms Thursday evening and Thursday night across portions of northern Indiana and Ohio. A series of waves of showers and storms will race eastward along the interface of a very strong southward-moving cold front. A zonal upper level jet streak across Lake Superior will max out around 150 kt 00Z Friday. Meanwhile moisture advection will allow PWATs to creep above 1.25 inches and dew points to spike into the 60s. Instability in the longer-range guidance has also nudged higher, into the 1,000 to 1,500 J/kg range of MUCAPE. While organized convection appears likely given favorable instability and shear profiles, the fast motion of the storms will remain the primary factor limiting the flash flooding threat. Thus, as regards flooding potential, with somewhat better environmental parameters than 24 hours ago but still dry soils in most areas, especially into Illinois, the area remains under a solid Marginal Risk. The greatest threat of isolated instances of flash flooding remains into the urban centers. Since most of the showers and storms will be occurring overnight Thursday night in the Marginal Risk area, any flooding will pose a heightened danger due to lack of visibility. Wegman Day 3 Valid 12Z Fri Mar 27 2026 - 12Z Sat Mar 28 2026 The probability of rainfall exceeding flash flood guidance is less than 5 percent. Oravec Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!6j19-uiKxziF4-eXvirZc55wOjiTAMiqLxHEihOCCSxs= MYlJgxF_KhKJOy_Xx4ctFAQ_nlR6djDUaQfuNT1xqKNGQ4c$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!6j19-uiKxziF4-eXvirZc55wOjiTAMiqLxHEihOCCSxs= MYlJgxF_KhKJOy_Xx4ctFAQ_nlR6djDUaQfuNT1xfwwtgm0$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!6j19-uiKxziF4-eXvirZc55wOjiTAMiqLxHEihOCCSxs= MYlJgxF_KhKJOy_Xx4ctFAQ_nlR6djDUaQfuNT1xVpH2cGo$=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 3.28-Linux * Origin: Capitol City Online (1:2320/107) ----------------------------------------------------------- [Voltar]