Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sat Sep 02 2023 03:26:19 AWUS01 KWNH 020326 FFGMPD AZZ000-UTZ000-NVZ000-CAZ000-020700- Mesoscale Precipitation Discussion 1022 NWS Weather Prediction Center College Park MD 1125 PM EDT Fri Sep 01 2023 Areas affected...eastern CA into eastern NV and far western UT Concerning...Heavy rainfall...Flash flooding likely Valid 020324Z - 020700Z Summary...Areas of flash flooding appear likely to continue for another few hours over far eastern CA into southern/eastern NV into far western UT. Peak rainfall rates of 1 to 2 inches in 30 minutes are expected. Discussion...GOES West infrared imagery has shown a general trend of warming cloud tops over the past 2-3 hours over the southwestern U.S., but pockets of new colder bursts continued over portions of southern NV into far northwestern AZ as of 03Z. Satellite and radar imagery showed new development of showers/thunderstorms from northern San Bernardino into Inyo counties in eastern CA, along with robust thunderstorm activity ongoing from southern NV into far northwestern AZ. Very anomalous moisture was present across the Southwest with the 00Z sounding from Las Vegas indicating 1.57 inches of PW, a standardized anomaly of about +3 for early September but lapse rates in the 700-500 mb layer were modest at 6.4 C/km. The 02Z SPC mesoanalysis page indicated that the best instability was located over northwestern AZ and from near Death Valley into southern and south-central NV with 1000-2000 J/kg in place, while reductions in instability have occurred elsewhere with MUCAPE dropping below 500 J/kg in several locations. Largely unidirectional flow from the south was supporting training of heavy rain with a history of cells producing 1 to 2 inches of rain in 30 minutes. Ongoing thunderstorms producing the highest rainfall rates across the area over southern NV into far northwestern AZ will translate northward over the next few hours into a region of lower and weakening instability, reducing rainfall intensity and lowering the flash flood threat beyond 05/06Z. However, a north-south axis of instability extending from San Bernardino/Inyo counties (Death Valley) and northward into central NV will likely allow for additional convective development with repeating and south to north training at times, supporting peak rainfall rates of 1-2 inches in 30 minutes. A localized flash flood threat may persist a bit longer for these western regions of the MPD area compared to those farther east. Lift will continue to be augmented by placement within the right-entrance region of a 90-100 kt jet max over northeastern NV at 00Z. This region of the Southwest is still experiencing above average streamflows related to heavy rainfall from Hilary 1-2 weeks ago and areas of flash flooding will continue to likely in the short term, but with lowering probabilities for flash flooding beyond 06Z. Otto ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!9qpwTXS_MrnO2TtcRWSijfYDg60LkoG8S2fzUNz7ChjVhFCF1-PoeYbbZzitvBf1VBIy= 2rioDl69obxo9eij4pQBsUc$ for graphic product... ATTN...WFO...LKN...REV...SLC...VEF... ATTN...RFC...CBRFC...CNRFC...NWRFC...NWC... LAT...LON 41291517 40671451 39441392 38791380 37051370=20 36441392 35941495 34921616 35081712 37421782=20 39971768 41201633=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) .