Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Mon May 05 2025 19:27:47 AWUS01 KWNH 051926 FFGMPD NYZ000-PAZ000-MDZ000-VAZ000-WVZ000-OHZ000-060045- Mesoscale Precipitation Discussion 0226 NWS Weather Prediction Center College Park MD 323 PM EDT Mon May 05 2025 Areas affected...portions of northern Mid-Atlanitc and central Appalachians to Lake Erie Concerning...Heavy rainfall...Flash flooding possible Valid 051846Z - 060045Z SUMMARY...Training of showers and thunderstorms from the northern mid-Atlantic and central Appalachians to the southern shore of Lake Erie may result in isolated to widely scattered areas of flash flooding through the early evening. Rainfall rates of 1-2 in/hr are expected. DISCUSSION...Visible satellite and regional radar imagery from 1830Z showed scattered showers and thunderstorms extending from northern VA into northern MD, northwestward into PA, western NY and eastern OH. These showers/storms were located northeast of a closed mid to upper-level low over the OH Valley with low level southeasterly flow advecting moisture northwestward across the region. Broadly diffluent flow aloft was in place to the northeast of the closed low, helping increase synoptic scale lift over the region. Blended TPW imagery showed that PW values ranged from ~1.4 inches to the southeast over northern MD to ~0.7 inches over eastern OH. SPC mesoanalysis data from 18Z showed MLCAPE was generally weak at 500-1000 J/kg with cloud cover or lower moisture values limiting instability to some degree. However, flash flood guidance values across a large portion of the region were about 1.0 to 1.5 inch/hr or slightly less and similarly oriented low level and mean steering flow wind vectors were supportive of repeating cells. While 925-850 mb winds were generally weaker than the mean steering flow, low level axes of confluence will support lines of showers/thunderstorms with a tendency for cell repeating and short term training. The environment is supportive of 1-2 in/hr rainfall rates and some indications from the RAP support a minor increase in the low level flow toward 00Z which could help increase the threat for backbuilding cells. The flash flood threat is expected to be isolated to widely scattered in nature through 01Z. Otto ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!7ash_-YrVg9-HmJOfkJNSKwXzW6mVwXXl1y78FanFERR4KeCRFwGXVp981GV7fwADlFJ= wMa5Jxe3gm5I0s6RlRrAnhs$ for graphic product... ATTN...WFO...BUF...CLE...CTP...LWX...PBZ...RLX... ATTN...RFC...MARFC...NERFC...OHRFC...NWC... LAT...LON 42437874 41107743 40007715 39257740 38697812=20 38777907 39138020 39888046 40198103 40628153=20 41728134 42258003=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) .