Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Sep 10 2023 10:05:32 AWUS01 KWNH 101005 FFGMPD NJZ000-DEZ000-MDZ000-VAZ000-101302- Mesoscale Precipitation Discussion 1050 NWS Weather Prediction Center College Park MD 604 AM EDT Sun Sep 10 2023 Areas affected...eastern Maryland, eastern Virginia, Delaware Concerning...Heavy rainfall...Flash flooding possible Valid 101002Z - 101302Z Summary...Bands of convection are repeating across the discussion area and resulting in spots of 1+ inch/hr rain rates. A few spots of excessive runoff could materialize in this regime over the next 2-3 hours or so. Discussion...At 0945Z, bands of showers and thunderstorms were oriented from south-southwest to north-northeast across the discussion area generally from near RIC to near DOV. The storms were in the general vicinity of a diffuse surface boundary that separated upper 60s F dewpoints across inland areas of Maryland/Virginia from mid-70s F dewpoints across southern and eastern portions of the DelMarVa peninsula. East of this axis, surface-based buoyancy (1000+ J/kg SBCAPE) was supporting deep updrafts, while 1.8 inch PW values were supporting efficient rainfall processes within the convection. A few spots of 1-2 inch/hr rain rates were materializing especially near/west of DOV and southwest of SBY. Objective analyses and water vapor imagery also suggested the presence of one or two weak shortwave troughs that were also likely agitating convection along the aforementioned axis this morning.=20 Some concern exists that the general regime will persist for a few hours this morning (perhaps through 12-13Z or so) and result in additional spots of 1-2 inch/hr rain rates (locally higher).=20 Steering flow aloft is generally parallel to the initiating surface boundary, which should encourage training/repeating of cells during this timeframe. FFG thresholds are generally in the 2.5 inch/hr range suggesting that 1) any flash flood threat should remain fairly isolated/tied to training and 2) areas containing sensitive ground conditions and will be most susceptible to excessive runoff.=20 The longevity of this threat is in question, however, as the waves partially responsible for the convection should lift away from the initiating boundary toward Pennsylvania/New Jersey later this morning. At least a few hours of marginal/isolated flash flood potential should exist in this regime. Cook ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!9mExTwgoubXMHjZS8UUNY5O8HUPU2XGBwUat7TBIE1XrLfbmZq9JenzDs2uJtxeTaWcJ= QwatbnuW0bgR5FEbgvGzBlU$ for graphic product... ATTN...WFO...AKQ...LWX...PHI... ATTN...RFC...MARFC...SERFC...NWC... LAT...LON 39537559 39207509 38427513 37607574 37027650=20 37177738 37627739 37927702 38347664 39027624=20 39377591=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 3.14-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .