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