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AWUS01 KWNH 222322
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COZ000-WYZ000-AZZ000-UTZ000-NVZ000-230520-

Mesoscale Precipitation Discussion 0827
NWS Weather Prediction Center College Park MD
720 PM EDT Wed Jul 22 2026

Areas affected...Intermountain West

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

Valid 222320Z - 230520Z

SUMMARY...Broken areas of slow-moving monsoonal showers and
thunderstorms with high rainfall rates will continue well into the
evening hours across the Intermountain West, including large areas
of Utah, western Colorado and southern Wyoming. Additional areas
of flash flooding are expected, and locally significant impacts
cannot be ruled out for some of the more sensitive slot canyon and
sloped terrain areas.

DISCUSSION...Deep monsoonal moisture is well entrenched across the
Intermountain West as moisture continues to lift north around the
western periphery of the deep layer subtropical ridge over the
southern Plains. GOES-W visible satellite imagery along with radar
shows broken coverage of heavy showers and thunderstorms with
generally slow cell-motions.

Multiple MCVs are embedded within the deeper layer flow across the
Intermountain West, and this energy coupled with MLCAPE values of
1000 to 1500 J/kg and PWs exceeding the 95th percentile of
climatology will continue to favor convection this evening with
high rainfall rates that will easily reach 1.5 to 2+ inches/hour.
Deep moisture as seen in OSPO ALPW data will be key to
facilitating these high rates, and there will be the added
contribution of upslope flow over the higher terrain.

The slow cell-motions and orographic focus for some of these heavy
showers and thunderstorms may drive some additional rainfall
totals through this evening of 2 to 3+ inches. These additional
rains are supported generally by the overall consensus of hires
CAMs, including the latest experimental WoFS.

These additional rains on top of earlier rains will locally
promote some enhanced runoff concerns and channeling of water away
from areas of steep terrain and especially through some of the
slot canyon locations. Additional flash flooding is expected
through this evening, and locally significant impacts will be
possible.

Orrison

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

ATTN...WFO...BOU...CYS...FGZ...GJT...LKN...PUB...RIW...SLC...
VEF...

ATTN...RFC...KRF...STR...TUA...NWC...

LAT...LON   42930877 42870708 42000590 40820566 39400636
            37680824 36841054 36691231 37121362 37861411
            38521417 39131382 40311210 41001115 42461017