Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed May 21 2025 06:28:37 AWUS01 KWNH 210626 FFGMPD VAZ000-NCZ000-211130- Mesoscale Precipitation Discussion 0300 NWS Weather Prediction Center College Park MD 225 AM EDT Wed May 21 2025 Areas affected...North-Central NC into South-Central VA Concerning...Heavy rainfall...Flash flooding possible Valid 210625Z - 211130Z SUMMARY...Locally slow-moving and repeating areas of showers and thunderstorms will be impacting portions of north-central NC and into south-central VA going through dawn. Isolated areas of flash flooding will be a concern as a result. DISCUSSION...Increasing warm-air advection and moisture transport riding up across the southern Mid-Atlantic region along with the arrival of a warm front will help to focus a gradual increase in shower and thunderstorm activity across north-central NC and especially south-central VA over the next few hours going into the dawn time frame. The latest surface analysis shows a front draped northwest to southeast across western and central NC and there is a pooling of elevated instability noted poleward of this boundary with MUCAPE values as high as 500 to 1000 J/kg nosing up through northern NC. A southwest low-level jet should becoming a bit better defined over the next few hours, and increasing to as much as 30 to 35+ kts by 09Z (5AM EDT) across the region based on the latest RAP forecast. This will result in increasing isentropic ascent and a further expansion of elevated instability up into south-central VA. Meanwhile, the arrival of mid-level troughing/energy from upstream over the OH/TN Valley region is expected to be interacting with the front and should foster a developing wave of low pressure along as it lifts gradually northward very early this morning. This will yield a corridor of strong low-level convergence/forcing near the front which will favor additional concerns for areas of elevated convection to develop and become a bit more concentrated. The 00Z HREF guidance suggests the potential for rainfall rates with some of the elevated convection to reach as high as 1.5 inches/hour. There may be some repeating cell-activity in a southwest to northeast fashion near an inverted surface trough north of the front, and that could support some totals by dawn of as much as 2 to 3+ inches. As a result, there may be some isolated concerns for flash flooding given more enhanced runoff potential. Orrison ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!6PMHzyXMGqTxPY0NYbbE2hpTC7xcRgMkL9w_DnLMkJxMXrY_qE4xHZ6UcsgA8D9-1_ai= bZ1uCCe6rvPjDvR3A-_k664$ for graphic product... ATTN...WFO...AKQ...RAH...RNK... ATTN...RFC...ALR...RHA...NWC... LAT...LON 37607716 36947679 36277833 36028016 36468049=20 37017980 37547839=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) .