Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Feb 06 2024 21:09:45 AWUS01 KWNH 062109 FFGMPD AZZ000-CAZ000-070300- Mesoscale Precipitation Discussion 0053 NWS Weather Prediction Center College Park MD 408 PM EST Tue Feb 06 2024 Areas affected...lower CO River Valley into western AZ Concerning...Heavy rainfall...Flash flooding possible Valid 062106Z - 070300Z Summary...Areas of flash flooding may develop across western AZ back to far southeastern CA through 03Z. Shallow convective cells are expected to develop later this afternoon with areas of training after 00Z. Rainfall rates of 0.5 to 1.0 in/hr will be possible within areas of training but may locally exceed 1 in/hr. Discussion...2030Z GOES West water vapor imagery showed a neutrally oriented and elongated mid to upper level trough extending from northern CA into the eastern Pacific, just west of 120W. The trough was moving east with a dry slot noted from northern Baja California into eastern CA/western AZ and southern NV. Low level moisture advection was occurring just ahead of the dry slot a seen on layered PW imagery from the lower CO River Valley into western AZ. However, an 18Z sounding from Yuma showed zero instability despite a precipitable water value just over 1 inch, due to a relatively warm 700-500 mb layer. Forcing for ascent will increase as the upper trough axis to the west continues to push eastward over the next 6 hours. Cooling of the 700-500 mb layer should allow instability to increase with recent forecasts from the RAP/HRRR showing up to ~500 J/kg MLCAPE developing through 00Z over western AZ. Aloft, the left exit region of a strong upper level jet max (~150 kt at 250 mb) is forecast to maintain favorable lift over western AZ. An increase in shallow convective cells is anticipated to occur near 00Z in the vicinity of the lower CO River Valley, with expansion into western AZ through 03Z. While steering flow should keep individual elements moving along at 3o to 40+ kt toward the NNE, this orientation is expected to align with a slow moving axis of similarly oriented convergence in the 850-700 mb layer over western AZ, allowing for training. In addition, roughly 30 kt of 700 mb flow will focus an upslope component to the flow into the Mogollon Rim, supporting enhancement of rainfall below ~7000 ft. While precipitable water values are forecast to decrease beyond 00Z with the eastward translation of the low level moisture axis, a brief window of overlap with higher instability/moisture could allow for 0.5 to 1.0 in/hr rates (perhaps locally higher) to support some 1 to 2+ inch totals through 03Z and possible flash flooding from the lower CO River Valley into western AZ. Otto ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!_prfAo1_rBa8XSzTvmx_oMzedxgmvJ_OfqPjIp7Yc3c9qZs-bLLlZXaClejyac7UBu3d= vrk2PuFFSToziU4RLs6oRzI$ for graphic product... ATTN...WFO...FGZ...PSR...TWC...VEF... ATTN...RFC...CBRFC...CNRFC...NWC... LAT...LON 35861385 35721317 35331278 35021227 34941182=20 34511177 33831221 32771288 32031353 32101427=20 32531504 33491513 34091493 34901458 35701453=20 35851419=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) .