Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Aug 09 2023 18:47:43 AWUS01 KWNH 091847 FFGMPD NMZ000-AZZ000-100046- Mesoscale Precipitation Discussion 0896 NWS Weather Prediction Center College Park MD 247 PM EDT Wed Aug 09 2023 Areas affected...Central AZ...Southwest NM Concerning...Heavy rainfall...Flash flooding possible Valid 091846Z - 100046Z Summary...Monsoonsal thunderstorms and agitated cu are expanding across portions of central AZ and southwest NM. Hourly rates upwards of .75-1"/hr could yield spot flash flooding this afternoon. Discussion...Visible satellite imagery shows an uptick in thunderstorm coverage within an increasingly agitated cu field across central AZ and southwest NM. The most robust activity on IR imagery was noted south and east of Flagstaff, with recent hourly rainfall estimates of 1-1.3" from KFSX and MRMS (although this could be inflated somewhat by hail). This activity remains tied to strong insolation across the Southwest, working in tandem with a weak shortwave trough along the periphery of a subtropical ridge axis over the Four Corners. In the upper-levels, some broad diffluence was analyzed by GOES-16 DMWs within an Eastern Pacific split-flow regime, which should encourage continued updraft development and maintenance. Monsoonal moisture remains in place across portions of southwest Arizona, with some Eastern Pacific enhancement noted just west of the MPD area, along the periphery of the ridge. While the main axis of anomalous moisture should remain west of the thunderstorm activity, PWATs approaching 1 sigma above climatology are still forecast to encroach into the area by tonight. The continued moistening of the area and diurnal heating will yield uncapped MLCAPE of 1000-2000 J/KG over the next several hours to support a focused area of deep convection with hourly rates upwards of ..75-1"/hr. Owing to the overhead ridge, minimal shear (10-20 kts) is present which will limit overall organization and longevity, but could also lengthen residence times of storms (particularly where outflows can collide). By 0Z tonight, the HREF blended mean suggests spotty rainfall totals upwards of 1-3" are possible (particularly across east-central AZ) where convection with these high rates can focus and re-generate with outflow collisions. Accordingly, an elevated signal for 6 hour QPF exceeding the 10 year ARI is noted within the MPD area (40-50%), with a small but still noteworthy signal (10-20%) for localized 100 year ARI exceedance closer to the AZ/NM border. Thus, flash flooding is considered possible before diurnal cooling diminishes convective coverage tonight. Asherman ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!7Oh8GJ3p3CGCpIOz4wa50E82JmvIulFeyGzWEuAfkvsUU0tATEj9YrIvYUEaUol0TcFV= fmPgwwoKK8Wa2qlewjHxgGI$ for graphic product... ATTN...WFO...ABQ...FGZ...PSR...TWC...VEF... ATTN...RFC...CBRFC...WGRFC...NWC... LAT...LON 36691309 35501117 34980998 34210811 33570806=20 33480870 33630965 33871109 34131255 34851340=20 35931371=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) .