Flash Flood Guidance
Issued by NWS
Issued by NWS
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508 AWUS01 KWNH 211836 FFGMPD COZ000-NMZ000-AZZ000-UTZ000-220035- Mesoscale Precipitation Discussion 0482 NWS Weather Prediction Center College Park MD 235 PM EDT Fri Jun 21 2024 Areas affected...Central to Southeast UT...West-Central to Southwest CO...Northeast AZ...Northwest NM Concerning...Heavy rainfall...Flash flooding possible Valid 211835Z - 220035Z SUMMARY...Increasing coverage of showers and thunderstorms can be expected going through the afternoon hours. Given the expectation of heavier rainfall rates to materialize, some isolated to widely scattered instances of flash flooding will be possible and especially for the more sensitive slot canyons and dry washes. DISCUSSION...Strong diabatic heating across much of central to southeast UT, southwest CO, northeast AZ and northwest NM is favoring a steady destabilization of the boundary layer, and this coupled with the poleward transport of anomalously deep moisture/high PWs will yield increasing coverage of showers and thunderstorms throughout the afternoon hours. MLCAPE values are already on the order of 1000 to 1500+ J/kg with the greatest instability currently situated over areas of central and southern UT. Coinciding with this is very moist deep layer southerly flow around the western periphery of the subtropical ridge that has nosed westward across the southern Plains. The mid and upper levels of the vertical column in particular show a well-defined connection to the moisture associated with former Tropical Storm Alberto that recently crossed into Mexico. Over the next few hours, there should be the development and expansion of orographically initiated convection that will be capable of producing very heavy rainfall rates. The CIRA-ALPW data shows strong concentrations of moisture that are in the 500/700mb layer and this will support highly efficient rainfall processes for enhanced rainfall rates. Some rainfall rates are expected to reach 1 to 2 inches/hour, and with cell-motions that could be relatively slow and anchored close to the terrain, there may be some spotty totals of 2 to 3+ inches by later this afternoon. Given localized slot canyon and dry wash sensitivities, these rains may foster isolated to widely scattered flash flooding concerns. Orrison ...Please see www.wpc.ncep.noaa.gov for graphic product... ATTN...WFO...ABQ...FGZ...GJT...PUB...SLC...VEF... ATTN...RFC...CBRFC...WGRFC...NWC... LAT...LON 40410956 40180848 39560762 38720700 37550666 36900677 35630705 34500711 33910753 33870858 34851013 35871234 36891286 38441254 39861131