Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Jun 05 2025 17:42:57 AWUS01 KWNH 051742 FFGMPD AZZ000-UTZ000-NVZ000-CAZ000-052341- Mesoscale Precipitation Discussion 0368 NWS Weather Prediction Center College Park MD 142 PM EDT Thu Jun 05 2025 Areas affected...Southern NV, Northwest AZ, Southwest UT and Southeast CA Concerning...Heavy rainfall...Flash flooding possible Valid 051741Z - 052341Z Summary...Increasing convection will lead to an isolated flash flood risk this afternoon across portions of the Southwest. Discussion...The focus for isolated flash flooding this afternoon appears to be across portions of southern NV, northwest AZ, far southwest UT and southeast CA. It is here where we are seeing the best overlap of instability and moisture today. Surface based CAPE is already over 1000 j/kg in spots, and forecast to increase towards 1500-2000 j/kg with mostly sunny skies helping destabilization. This is notably higher than the instability 24 hours ago. PWs over this region generally range from 0.75" to 1.25" and are a tad higher than 24 hours ago as well. This combination of increased instability and PWs should support intense rainfall rates in convection. While not widespread, probabilities from the HREF and REFS indicate that localized 1"+ an hour rainfall is probable. Deep layer mean flow is only 5-15 kts out of the west, allowing for just some slow eastward cell movements today. Cells should stay tied to terrain features long enough to produce locally heavy rainfall, and when they do move off the terrain brief cell mergers could locally enhance rainfall magnitudes. While widespread impacts are not anticipated, localized flash flooding is probable in this setup. Based on current radar and satellite trends the greatest convective coverage will probably be over northwest AZ...but there is a strong signal for isolated to scattered development shortly over southern NV as well. In fact neighborhood probabilities of exceeding 3 hr FFG get as high as 60-80% in the experimental 06z REFS over southern NV. The risk over adjacent areas of CA is more conditional, but isolated cells may try to develop and/or propagate into this area later this afternoon. Southwest UT is a bit more uncertain, with ongoing showers impacting destabilization. But still a chance we get some stronger redevelopment over this corridor this afternoon as well. Chenard ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!_s372gQ_PLTmhwGVAl9VJI15IQotqoJBrrfYh0Bq3qZFXnv9SGFYi8eEn8F2iffMfo0D= z0CceIhCx0tBYfUu_Lg0IXg$ for graphic product... ATTN...WFO...FGZ...SLC...VEF... ATTN...RFC...RSA...STR...NWC... LAT...LON 38381393 38301304 38071214 37351183 36421153=20 35801157 35301190 34991289 34891410 34951476=20 34651566 34611576 34581620 34971654 35481647=20 36181616 36691595 37291577 37771522 38161460=20 =20=20=20=20=20=20=20=20=20=20=20=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) .