882
AWUS01 KWNH 272301
FFGMPD
COZ000-NMZ000-AZZ000-UTZ000-280500-

Mesoscale Precipitation Discussion 0508
NWS Weather Prediction Center College Park MD
700 PM EDT Thu Jun 27 2024

Areas affected...Southern UT...Northeastern AZ...Western NM

Concerning...Heavy rainfall...Flash flooding likely

Valid 272300Z - 280500Z

SUMMARY...Flash flooding is likely to continue into this evening
as backbuilding and training thunderstorms cause scattered
instances of flash flooding. Locally significant flash flooding
expected.

DISCUSSION...Backbuilding and training thunderstorms continue
across Utah and northeastern Arizona this afternoon and evening as
the passage of an upper level shortwave and unidirectional WSW
flow of anomalously high and near daily record moisture fuels
strong thunderstorms capable of locally heavy rainfall to 2 inches
per hour. Training storms will continue to cause and add to
ongoing flash flooding, resulting in some locally significant
flash flooding through this evening. SPC Mesoanalysis shows SBCAPE
values in this area remain as high as 3,000 J/kg...showing that
the WSW flow continues to advect instability into the area and the
storms so far have not depleted the instability. Thus, the storms
should have no problem maintaining their strength into the evening.

Anomalous moisture feeding the storms that are moving towards the
east and northeast are running into the local terrain across Utah
and Arizona. Ongoing and new flash flooding is likely as the
storms continue to train over many of the same areas. The
unidrectional flow is allowing upslope into the terrain to
contribute to the potential flash flooding as storms get hung up
along the terrain, increasing the time of heavy rain locally.

Loss of diurnal heating and the departure of the upper level
shortwave reducing the environmental forcing should allow for a
slow diminishing of thunderstorm activity after sunset. However,
local upslope may slow that process along the mountains.

Wegman

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...ABQ...FGZ...GJT...SLC...VEF...

ATTN...RFC...CBRFC...WGRFC...NWC...

LAT...LON   39671187 39621064 39541029 39350993 38750966
            38380881 37990874 37300942 36860916 36110809
            35450777 34550733 33810904 33780934 33670954
            34131019 34421087 34811162 35381212 36031219
            36381254 37131255 37421267 38981295