AWUS01 KWNH 121807
FFGMPD
COZ000-NMZ000-AZZ000-UTZ000-122330-

Mesoscale Precipitation Discussion 1074
NWS Weather Prediction Center College Park MD
206 PM EDT Fri Sep 12 2025

Areas affected...Western CO...Eastern UT...Northwest NM...Far
Northeast AZ...

Concerning...Heavy rainfall...Flash flooding possible

Valid 121805Z - 122330Z

SUMMARY...Quick bursts of sub-hourly .5-.75" totals and isolated
repeating spots that may have localized maxima to 1.5" through the
afternoon will push naturally low FFG values, especially near burn
scars and steep gulleys. A few spots of flash flooding are
possible through the evening hours.

DISCUSSION...GOES-East WV suite depicts a global scale meridional
trough between 117W and 114W slowly shifting eastward, with strong
core of energy just west of the base of the overall trough across
the Lower Colorado Valley providing a favorable downstream
environment to draw remaining enhanced sub-tropical moisture out
of the Sea of Cortez northward across the Four Corners region into
western CO. CIRA LPW, denotes core of the best moisture remains
along and just west of the NM/AZ line through the lowest levels
though surface Tds across the Four Corners into Western CO still
above normal with mid-50s in AZ/NM and upper 40s to low 50s in the
higher altitudes of the San Juans and further north.
Additionally, WV suite shows a kink in the upper level jet pattern
with expanding right entrance region across S UT into CO as the
upstrem jet core rounds the base over the Lower Colorado. This
will further enhanced surface to 700mb southwesterly flow while
also providing solid larger scale UVVs and outflow to maintain
convective clusters.

Currently best convergent clusters reside on the northwest nose of
the deeper level moisture across East central UT starting to
spread across west-central to NW CO. Total Pwats of .75-1" are at
1.5 standard anomalies and with strength of deep layer flux
convergence is supporting some above average efficiency
thunderstorm activity (including some that induced flash flooding
further west in E UT). This includes increasing agitation/TCU
field across SE UT, though larger clusters capable of .5"/hr
totals continue to expand over SW CO. Cells are fairly
progressive, but also have a weak training/repeating orientation
as the overall height-fall axis presses eastward very slowly over
the next few hours. Scattered to numerous spots of .25-.5"
totals are probable, though isolated sub-hourly totals up to .75"
and a random potential for repeats may result in a spot or two of
1-1.5". The sheer rate within complex terrain and natural low FFG
values in that .5-1"/hr range, along with noted burn scars
suggested widely scattered incidents of flash flooding remain
possible this afternoon into evening.

Further south, the speed max rounding the base of the trof and
overall slow eastward motions further increased DPVA and favorable
enhancement of weak shortwave feature lifting out of Northern Old
Mexico into SE AZ. Stronger thunderstorms are developing at the
intersection of the SSWly enhanced LLJ flow and the Mogollon
Rim/San Francisco Mtns. Redevelopment along those ridges is
likely to continue and support downstream repeating clusters
across W and NW NM and far eastern AZ. Deeper layer moisture of
1.25 to 1.4", especially loaded below 700mb suggest slightly
higher efficiency than further north and spots of 1" are probable
and possible to induce localized flash flooding in prone arroyos.

Gallina

ATTN...WFO...ABQ...BOU...FGZ...GJT...PUB...SLC...

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

LAT...LON 40810709 40570572 39460533 36370664 35080728
34280778 33850854 33900944 34340996 34831000
35950987 36970970 37620997 38471034 39690972
40650849

$$
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