562
FXUS65 KTWC 141545
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
845 AM MST Mon Jul 14 2025

.SYNOPSIS...Above normal temperatures will continue through
Tuesday with temperatures dropping back down to seasonable levels
as deeper atmospheric moisture moves into the area. Southeast
Arizona will experience a mid-grade Monsoon day today, with
increasing activity expected through the week. Strong and gusty
outflow winds with areas of blowing dust are the primary threat
again today, especially across Graham county to the northeast of
Tucson. Showers and thunderstorm with the potential for heavy
rainfall will be present from Tucson to the south and southeast
Tuesday and Wednesday.

&&

.UPDATE...Latest visible satellite imagery shows mostly clear to
partly cloudy skies across Pima/Pinal/Graham and Greenlee Counties
with mostly cloudy to overcast conditions for much of Santa Cruz and
Cochise Counties where a few residual light showers continue. PWAT
values this morning range from 0.8 inches in the White Mountains,
then progressively gets more moist to the south and west with PWATs
at around 1.3 to 1.4 inches over the central and western deserts as
these locales have reinforcing Gulf Surge moisture. Latest thinking
hasn`t really changed for today. We`re going to be focused on two
areas of convective development, one over the White Mountains that
will push to the southwest and the other over Santa Cruz/western
Cochise County that will move to the west to southwest. The clouds
this morning over Cochise County will likely slow development down
there with greater chances for initiation over Santa Cruz County.
The southern storms will produce both gusty winds and locally heavy
rain while the northern storms will have more of a wind and blowing
dust threat given the drier sub-cloud layer across Graham County.
The Tucson area will be on the northern periphery of the southern
activity as outflow moves north to northwest, and for the northern
storms coming from the White Mountains there is lower confidence on
whether they will lose some of their punch as they move southwest.
Therefore, the possibility for strong storms exists from mid
afternoon into early evening for the Tucson Metro with strong winds
being the primary threat but confidence is low and this will be
dependent on smaller scale details including outflow mergers.
Current forecast is in good shape. No updates this morning.


&&

.DISCUSSION...The upper pattern this morning is defined an upper-
level ridge of high pressure off the coast of Southern California
extending NE into the Great Basin with a weak trough developing to
the SSE of this feature near the northern Gulf of California. At
500 mb, we are seeing a secondary high center develop away from
the mean ridge near Las Vegas this morning, with this high progged
to build into northern Arizona over the next 24 hours. As this
occurs, we will see a diffluent northwest flow with favorable
deformation aloft near the White Mountains this afternoon/evening.
At 300 mb, we see a more established upper low developing near
the Baja-spur by 00Z Tuesday, with a weakness/col aloft over the
far SE corner of Arizona.

This setup should allow for two favored areas for thunderstorm
development today; one near the White Mountains and the other near
southern Cochise/NE Sonora Mexico. The stronger area of storms
will be those originating near the White Mountains. The upper
pattern is more of a classic rim-shot pattern that typically has a
higher impact on the Tucson Metro Area with storms moving SW off
the higher terrain of the Mogollon Rim toward Tucson. Although we
are starting to see a surge of low-level gulf moisture move into
the lower deserts of SW AZ this morning, significantly drier air
still resides NE of Tucson. This will make conditions favorable
for strong and gusty thunderstorm outflow winds as these storms
initially move SW off of the Whites. The 14/00Z HREF has a 70-90%
neighborhood (40-km) probability of wind gusts in excess of 30
kts, and a 10% neighborhood probability of severe wind gusts
exceeding 50 kts across Graham county as these storms. Blowing
dust will be a concern in Graham county. As these storms move SW
into the Tucson Metro Area early this evening, timing will be
important. If the lower- level moisture in the lower desert spills
into the city during the afternoon, the outflow potential will be
lower as evaporation rates for downdrafts in the sub-cloud layer
decreases. My guess is that we see outflows that near severe
levels this evening in Tucson. The 14/00Z HREF has eastern Pima,
Santa Cruz and the southern Tohono O`odham Nation with a 50-70%
neighborhood probability of wind gusts 30+ kts. In any event, this
area of storms will continue to dive SW into central and western
Pima county, eventually merging with the second area of storms
moving west from southern Cochise county.

This storm cluster will help re-inforce lower-level moisture back
up into the lower deserts Tuesday morning as it moves west thru
northern Sonora Mexico. The 14/00Z ensembles of the ECMWF and GEFS
are both still excited with regards to the moisture across Southeast
Arizona, depicting precipitable water values between 1-2 standard
deviations above normal across the CWA Tuesday through Thursday.
Expect the upper high center at 500 mb shift east to the Four
Corners Tuesday afternoon, then into New Mexico/Texas Wednesday
afternoon. Favorable diffluence/deformation aloft will be present
from Tucson S and SE Tuesday. Given the moisture in place, we will
move from having strong to severe outflow winds/blowing dust
threats today...to heavy rainfall/flash flooding risk Tuesday and
Wednesday. The 14/00Z HREF indicated a neighborhood (40-km)
probability of 50-70% of 3-hr rainfall exceeding an inch across
eastern Pima, southern TON, Santa Cruz and SW Cochise county
Tuesday afternoon, with a 10% neighborhood probability of
exceeding 3 inches in Santa Cruz and far SW Cochise. After
coordinating with WPC, they have added SLGT Risk for flash
flooding on their Day 2 Excessive Rainfall Outlook Tuesday in
areas of Southeast Arizona from Tucson south and southeast. My
guess that Tuesday will be the heaviest rainfall. With the upper
high shifting east into NM/TX Wednesday, it has that look like we
will have an MCS develop Tuesday night with a remnant MCV moving
north across the CWA Wednesday delaying pcpn as some of the CWA
will be in the subsident wake. Its hard to have high confidence in
this being exactly what happens this far out in the Monsoon, but
pattern recognition/experience suggests the possibility. WPC kept
SLGT risk out of Wednesday for now, despite the available
moisture.

Otherwise, deep southerly flow expected late in the week into next
weekend. This will maintain the more active pattern for thunderstorms
across Southeast Arizona through the forecast period, with the
favored locations for stronger storms residing across the eastern
half of the forecast area.

&&

.AVIATION...Valid through 15/12Z. SCT-BKN 7-11k ft AGL BKN 12-15k
ft AGL thru the period. SCT -TSRA/-SHRA developing in the White
Mountains north of KSAD and along higher terrain from KOLS through
KDUG moving W-SW across Southeast Arizona between 14/20Z-15/04Z.
Thunderstorms possible in KTUS vicinity between 14/23Z and 15/04Z.
Wind gusts of 40-50 kts with 1-3SM VSBY in BLDU are possible with
the thunderstorms, especially near KSAD. Otherwise, SFC winds
light and terrain driven through 14/20Z, then WLY less than 10
kts. Aviation discussion not updated for TAF amendments.

&&

.FIRE WEATHER...An uptick in monsoon activity is expected to continue
throughout the week. Deeper atmospheric moisture moving into the
area Tuesday through Thursday will increase the potential for
heavy rainfall and localized flash flooding. Temperatures will
remain above normal through tomorrow, then drop back down to near
or slightly below normal by mid week. Winds will remain westerly
from 10-15 mph, with occasional gusts at or above 25 mph.
Afternoon RH values in the low lying areas will be between 10-15%
today, then 20-30% through the remainder of the week.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...None.

&&

$$

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