Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Aug 01 2024 19:22:21 AWUS01 KWNH 011922 FFGMPD WIZ000-020120- Mesoscale Precipitation Discussion 0775 NWS Weather Prediction Center College Park MD 321 PM EDT Thu Aug 01 2024 Areas affected...Central Wisconsin Concerning...Heavy rainfall...Flash flooding possible Valid 011920Z - 020120Z Summary...Expanding slow moving convection may result in isolated to scattered flash flooding over the next several hours across portions of Wisconsin. Discussion...Convection is expected to continue to increase in coverage over central WI over the next few hours as a well defined mid level low moves into the area. Already seeing slow moving convection near a stationary front, and the approaching mid level low should only increase forcing over this region. The stationary front over the area will act as a persistent low level forcing mechanism, which combined with relatively weak deep layer mean flow, supports slow moving and repeat convection. PWs across this axis are around 1.7" and MLCAPE around 1500 j/kg...both supportive of heavy rainfall rates. IR imagery indicates the ongoing convection is not all that deep...with the more shallow nature of convection likely indicative of some warm rain processes increasing rainfall efficiency. As the mid level low approaches convection will probably grow more vertically with colder cloud tops...which may decrease rainfall efficiency a tad, although still would expect heavy rainfall rates. The favorable thermodynamic environment for heavy rates combined with the slow storm motions suggests at least an isolated to scattered flash flood risk will exist over the next few hours. The 12z HREF neighborhood probabilities of 3" are 30-60%, and localized 3"+ totals are supported by recent HRRR runs as well. The one limiting factor is the general lack of deep layer shear to organize/maintain convection. Without this ingredient convection will probably pulse up and down in intensity and likely limit the upper bound of rainfall totals. This is also indicated by the significant drop in 5" exceedance probabilities from the HREF compared to 3". Overall expect convection to be capable of localized ~2"/hr rainfall, with totals over the next 6 hours locally getting into the 2-4" range. This is expected to result in at least a few instances of flash flooding. Chenard ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!8-FfiamONE4aKc3fGbodS7iYlqdPwpLZmWXM9Is0lKbPSUOYqcaEeCG-0N9mfWd-ugTm= Mkg6xgI7V3MPv3SNWoP8Zf8$ for graphic product... ATTN...WFO...ARX...DLH...GRB...MKX...MPX... ATTN...RFC...NCRFC...NWC... LAT...LON 46129002 46128961 46028925 45878904 45368893=20 44918877 44378823 43838811 43258819 42808848=20 42778922 43239000 43829045 44259073 44939102=20 45499104 45839091 46069059=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) .