Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Feb 16 2025 15:46:37 FOUS30 KWBC 161545 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 1045 AM EST Sun Feb 16 2025 Day 1 Valid 12Z Sun Feb 16 2025 - 12Z Mon Feb 17 2025 The probability of rainfall exceeding flash flood guidance is less than five percent... The stronger line of showers continues to rapidly advance across the Piedmont of Virginia into the Carolinas with much of the cores continuing to weaken as they progress across the colder surface temperature areas experiencing cold air damning. The warm front is lifting north, with some modest 500-1000 J/kg of CAPE starting to help redevelop some convective activity across the Coastal Plain=20 but timing for this reinvorgoration over saturated ground=20 conditions is rapidly closing as the line is expected to clear the=20 coast by 18-19z. HREF probability still have a few spots of .5"/hr over 40% across S central MD, SE VA into the Delmarva; but this=20 also seems slightly inflated given over- estimation of trends=20 earlier this morning as well. South into the Carolinas, the FFG=20 values are much higher to be in reach even the stronger=20 thunderstorms/rain rates.=20 So in coordination with local forecast offices, the Marginal Risk=20 was reduced to below 5% coverage. While this means rainfall induced flooding and flash flooding is nearly over , there will be=20 remaining channeling of on-ground waters that will continue to=20 result in longer-duration, significant hydrological/riverine=20 flooding. Continue to pay attention to local emergency management=20 and water related warnings/discussions from the National Water=20 Center, River Forecast Centers and local National Weather Service=20 offices for further information.=20 Gallina=20 ----Prior Discussion---- A line of showers and thunderstorms moving ahead of an deepening low pressure center and its trailing cold front are forecast to move from the central Appalachians through the Mid-Atlantic this morning. These storms are expected to move steadily across the region, producing a period of brief, but potentially heavy rainfall. While widespread additional heavy accumulations are not expected, recent precipitation, including that which has fallen over the past 24 hours, has saturated soils across portions of the region. 1-hr FFGs under a 0.25 inch in some areas suggest that even brief heavy rainfall may exacerbate any ongoing flooding conditions. FFGs indicate that southern West Virginia into southwestern Virginia are especially susceptible. Pereira Day 2 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 Day 3 Valid 12Z Tue Feb 18 2025 - 12Z Wed Feb 19 2025 ....THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ALONG PORTIONS OF THE CENTRAL GULF COAST... Strengthening southwesterly winds ahead an amplifying upper level shortwave and an associated cold front are expected to draw deeper moisture into parts of the Gulf Coast, with PWs climbing to around 1.5 inches. This moisture along with increasing lift and instability may be sufficient for heavy rainfall rates. Models also offer a modest signal for training storms ahead of a surface low that is forecast to develop and advance east along the coast Wednesday morning. This may help support localized heavy rainfall, with some potential for isolated flash flooding, especially in urbanized areas. Pereira Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!_QW690unNrmHrHo_GEXv9MFxeWydFEYwrBcYFF_JEcmb= kfGmgmdhB2hunMOXvizNIriek89SAj-bukfLVKrSzjwnsww$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!_QW690unNrmHrHo_GEXv9MFxeWydFEYwrBcYFF_JEcmb= kfGmgmdhB2hunMOXvizNIriek89SAj-bukfLVKrS9h59rMY$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!_QW690unNrmHrHo_GEXv9MFxeWydFEYwrBcYFF_JEcmb= kfGmgmdhB2hunMOXvizNIriek89SAj-bukfLVKrSsGwfItg$=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) .