Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Mon Jul 03 2023 18:08:44 AWUS01 KWNH 031808 FFGMPD NYZ000-PAZ000-032300- Mesoscale Precipitation Discussion 0627 NWS Weather Prediction Center College Park MD 208 PM EDT Mon Jul 03 2023 Areas affected...Upstate New York, far northern Pennsylvania Concerning...Heavy rainfall...Flash flooding possible Valid 031807Z - 032300Z Summary...Showers and thunderstorms will increase in coverage through the the afternoon and train along a stationary boundary. Rainfall rates of 1-2"/hr are likely, which could result in 2-3" of rain with locally higher amounts. Flash flooding is possible. Discussion...The GOES-E WV imagery this aftn shows an impressive plume of moisture arcing into the Northeast downstream of a sharp mid-level trough over Ontario, with a mid-level deformation axis positioned west to east over Upstate New York. At the surface, WPC is analyzing a stationary front draped across the region, into which moisture confluence is impressive, and a shortwave is moving near Lake Erie atop this boundary. PWs across the area are generally around 1.7 inches, measured at 1.79 on the 12Z KBUF U/A sounding, which is well above the 90th percentile for the date. This morning sounding was also characterized by a fully saturated column with moist adiabatic lapse rates, and warm cloud depths above 10,000 ft indicating efficient warm rain processes will dominate today. This is already being reflected by radar-estimated rain rates from KBUF of 1.5-2"/hr, driven by SBCAPE rising above 1500 J/kg. As the aftn progresses, much of the available high-res guidance indicates that convection will expand and intensify as SBCAPE rises to around 2000 J/kg in the still saturated column. Much of the activity is likely to develop within the warm sector south of the front, and ahead of weak impulses that are progged to move east through the flow. Rainfall rates within the deeper convection could reach 2-3"/hr as reflected by HREF probabilities and the HRRR 15-min rainfall product reaching 0.75 inches in places. Storm motions as reflected by forecast 0-6km mean winds will be generally progressive around 15 kts to the east, but Corfidi vectors aligned to the mean flow and along the front will support training into this evening. While convective coverage is still somewhat uncertain, any storms that do develop could organize through effective bulk shear of 20-25 kts, which then through training or multiple rounds could produce 2-3" of rain with locally higher amounts. 14-day rainfall across this area has been generally near normal, but in some places is above 150% of normal, helping to pre-saturate the soils. Additionally, 24-hr MRMS rainfall of 1-3" has further contributed to priming the region. This has lowered 1-h and 3-h FFG to 0.5 inches and 1 inch, respectively, which the HREF indicates has a 40-60% chance of being exceeded. Any of these intense rain rates moving over the saturated soils could result in instances of flash flooding through the aftn and into the evening, and it is possible additional concerns may persist into tonight. Weiss ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!-4dOSFm49Ps30cLcNm3cZMnOlTmtqbY7q0rbRKZpFxNyYpaJyP8LYN03nEJizQsoPBZW= CYnNEIqoSMjsAyUWDl-JyeY$ for graphic product... ATTN...WFO...ALY...BGM...BUF...CTP...OKX...PBZ... ATTN...RFC...MARFC...NERFC...OHRFC...NWC... LAT...LON 43287536 43167437 42897359 42417350 41877367=20 41477417 41527492 41637600 41617694 41497761=20 41437819 41507883 41637913 41907916 42257902=20 42617866 42897813 43177722 43257616=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) .