


Flash Flood Guidance
Issued by NWS
Issued by NWS
386 AWUS01 KWNH 170445 FFGMPD VAZ000-NCZ000-170900- Mesoscale Precipitation Discussion 0077 NWS Weather Prediction Center College Park MD 1244 AM EDT Mon Mar 17 2025 Areas affected...northeastern North Carolina into southeastern Virginia Concerning...Heavy rainfall...Flash flooding likely Valid 170444Z - 170900Z Summary...Deep convection continues to develop across North Carolina and stream north-northeastward into southeastern Virginia. 1-2 inch/hr rain rates persist in the strongest activity. This regime should continue for at least another 3-4 hours, posing a continued risk of flash flooding. Discussion...Convection has continued to refire along a surface trough extending from just east of Richmond, VA to just east of Raleigh, NC over the past couple hours. This trough has allowed for convective development to remain oriented generally parallel to deep south-southwesterly flow aloft, allowing for substantial training in a few locales. Additionally, 1.5+ inch PW values and 500 J/kg SBCAPE supports efficient rainfall processes with the ongoing storms. Ascent from upstream mid-level troughing continues to result in ascent/height falls over the trough as well. These factors support continued, SSW-NNE oriented training bands of storms for the next 2-4 hours or so. Over time, eastward translation of the surface trough and mid-upper forcing will lead to an eventual end of heavy rainfall potential - most likely after 08-09Z. Between now and then, concern exists that these training convective bands could eventually make it in to populated, sensitive areas of southeastern Virginia where lower FFGs (around 1 inch/hr) could result in a few areas of flash flooding. It is not out of the question for rain rates to double those lower values (generally extending from near Richmond southeastward through Virginia Beach) and lead to locally significant impacts. Cook ...Please see www.wpc.ncep.noaa.gov for graphic product... ATTN...WFO...AKQ...MHX...RAH... ATTN...RFC...MARFC...SERFC...NWC... LAT...LON 37587690 37067613 36627606 36017677 35477799 36767811 37557755