Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sat Feb 15 2025 23:52:39 FOUS30 KWBC 152352 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 652 PM EST Sat Feb 15 2025 Day 1 Valid 01Z Sun Feb 16 2025 - 12Z Sun Feb 16 2025 ....THERE IS A HIGH RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF THE LOWER MISSISSIPPI, TENNESSEE, AND OHIO VALLEYS... Recent radar/satellite imagery early this evening shows a=20 continued axis of training moderate to heavy rainfall from eastern and south Arkansas to the border of IN/IL with KY then across southern WV into southwest VA. Inflow at 850 hPa is from the west- southwest at 50+ kts and was quasi- parallel on the=20 cool/overrunning side a set of warm fronts in an area of low- to=20 mid-level frontogenesis. The expectation is for the flow to remain=20 parallel in nature of the above frontal alignment and for the=20 western edge to show increased forward propagation with time as the cold front advances. Precipitable water values are 1.3-1.5" and=20 flash flood guidance is quite depressed, approaching zero, within=20 an area of completely saturated, if not flooded, soils. The=20 various Moderate and High Risk areas remain supported, given the=20 above. The best instability remains across portions of the Mid-=20 South, where mesocyclone formation and training convective bands=20 are most likely over the next few hours. Significant rainfall remains in the offing for a large portion of the Lower Mississippi and Ohio Valleys due to current rainfall trends and another episode of heavy rainfall from the advancing front across very sensitive regions. Expect a continued large=20 expanse of flash flood and areal flood warnings into tonight with=20 more flash flood emergencies possible. Confidence remains very high for potential life- threatening flash flooding occurring in the=20 above areas. Roth Day 2 Valid 12Z Sun Feb 16 2025 - 12Z Mon Feb 17 2025 ....THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL IN PORTIONS OF THE MID-ATLANTIC... 20Z Update: The main change from the previous forecast was a further expansion of the MRGL risk to the west and southwest across southwestern VA and northwestern NC where trends within the 12z HREF highlights lingering convective schemes over the terrain in the first 3-6 hr window of D2, an area that will be well-primed and likely experiencing ongoing flood concerns from the previous period. Already some significant flooding within the far southwest section of VA due to the combination of persistent mod/heavy rainfall and snow melt. HREF 1"/6-hr probs are between 50-70% with much of the precip falling in a few hrs within the short term window 12-18z Sun. Progressive nature of the precip will aid in maintaining a very low-end prob for flash flooding for other areas downstream within the Mid-Atlantic, including the metro corridor from Richmond to Boston. Still maintaining non-zero probs for those areas across the Megalopolis, but prob fields are not signaling much in the way of confidence to expand the risk area further north, so maintained continuity from previous forecast. Kleebauer ...Previous Discussion.. A Marginal Risk was maintained across portions of the Mid-Atlantic, mainly as a reflection of the potential for brief, heavy rains advancing along the cold front moving across the region early in the period. While these storms are expected to be progressive, with widespread additional heavy totals not expected, moist soils further saturated by rain in the previous period may encourage isolated flash flooding responses, especially across portions of southwestern to central Virginia. Pereira Day 3 Valid 12Z Mon Feb 17 2025 - 12Z Tue Feb 18 2025 The probability of rainfall exceeding flash flood guidance is less than five percent. Pereira/Kleebauer Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!6Gb1cFobp1lyu55z0Pn2167lfJLlSl3FWpkBaLuXnRhd= eBBm4GLG7BO1ipCLFk_EYmpkeUEJzsobB4N_X7mqaPZ78pI$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!6Gb1cFobp1lyu55z0Pn2167lfJLlSl3FWpkBaLuXnRhd= eBBm4GLG7BO1ipCLFk_EYmpkeUEJzsobB4N_X7mqAj12iRY$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!6Gb1cFobp1lyu55z0Pn2167lfJLlSl3FWpkBaLuXnRhd= eBBm4GLG7BO1ipCLFk_EYmpkeUEJzsobB4N_X7mqfDmeo-w$=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) .