Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Feb 18 2024 03:00:33 AWUS01 KWNH 180300 FFGMPD CAZ000-180758- Mesoscale Precipitation Discussion 0061 NWS Weather Prediction Center College Park MD 959 PM EST Sat Feb 17 2024 Areas affected...Bay Area into the Sacramento Valley Concerning...Heavy rainfall...Flash flooding possible Valid 180258Z - 180758Z SUMMARY...Heavy rainfall rates are expected with bands of locally stronger convection over the next few hours. Areas of flooding will be possible over the next few hours. DISCUSSION...The latest GOES-W IR satellite imagery in conjunction with dual-pol radars from the Bay Area and the Central Valley have been showing some uptick in small-scale bands of convection with some some cooling cloud top activity noted as a cold front arrives in off the Pacific Ocean. Strong forcing aloft associated with the arrival of an upper-level trough working in conjunction with a ribbon of modest instability and localized orographics have been allowing for rainfall rates to increase over the last few hours, and over the last hour, some rates have been reaching as high as 0.5" to 1.0"/hour with the stronger semi-organized convective cells. Over the next few hours, some semi-organized linear bands of convection will continue to impact areas near and a bit south of the Bay Area, but also farther east into the Sacramento Valley where even some brief training of convection will be likely given the orientation of the activity with the deeper layer southwest flow aloft ahead of the upper-level trough. Expect rainfall rates to reach easily into the 0.5" to 1.0"/hour range with the convection over the next 2 to 3 hours, which will foster some additional rainfall totals of as much as 1.5 to 2.5 inches. Already there have been some areas of flooding around the Bay Area, and additional areas of flooding will be possible as these additional rounds of heavy rainfall advance inland. Gradually the passage of the cold front will allow for the deeper moisture axis to advance well off to the east, along with the better forcing aloft, and thus the rainfall rates should gradually wane later this evening and overnight. Orrison ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!-5m-PBfVj9KAY666_ldtIp-An_jxnPPY3ijNl_rhngt7Rnv3td4-ParWnpY36tyWtMvx= L9Ag2R42fhHgMtUsOeS_mwU$ for graphic product... ATTN...WFO...MTR...STO... ATTN...RFC...CNRFC...NWC... LAT...LON 40472215 40372146 39562094 38392081 37262113=20 36982183 37012220 37542259 38672234 39422234=20 40202255=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) .