Severe Thunderstorm Warning 182, NWS Tucson, AZ

Area Forecast Discussion
National Weather Service Tucson AZ
1211 PM MST Tue Aug 11 2026

.SYNOPSIS...The combination of a shifting weather pattern aloft
and deep moisture residing across the region will result in
scattered to numerous showers and thunderstorms across Southeast
Arizona with the potential for heavy rain the next few days.
Although most of the storms will produce between a half and one
inch of rain, the stronger storms are capable of producing
locally heavier amounts between 1-3 inches. Otherwise, a drier
southwest flow aloft will bring a downturn in daily storm
activity Friday into the weekend. High temperatures will be near
normal today, then 3 to 6 degrees below normal tomorrow and
Thursday before temperatures warm again into the weekend.

&&

.DISCUSSION...The upper pattern late this morning is defined by
an upper-level ridge of high pressure centered just east of the
Four Corners and an inverted trough oriented SW-NE across Chihuahua
Mexico. The moisture profile is defined by the GOES precipitable
water imagery, indicating some drier air hanging out along the
AZ/NM border (PWATs 1.00-1.10 inches), with deeper moisture
moving east into Tucson (PWATs 1.25 inches) and very deep
moisture PWATs between 1.50-2.00 inches across the western
deserts.

I have been around here long enough to know that the bigger and
more active thunderstorm days for Southeast Arizona usually
align with big movements of the upper high. Today is no different.
The upper-high center near the Four Corners will move east over
the next 24 to 36 hours, eventually making its way to central
Oklahoma by 13/00Z Wednesday afternoon. As this happens, not
only will we experience general deformation aloft assisting
lift across the region, but that inverted trough in Chihuahua
Mexico will rotate up into the far SE corner of AZ by this
afternoon providing a better lifting mechanism. The best lift
today will initially occur across SRN Cochise early this
afternoon, then expand toward the NW into north-central Pima and
SE Pinal counties by 12/06Z this evening.

The drier airmass residing along the AZ/NM border today will
increase the potential for strong organized thunderstorm outflows
with the initial development. This is supported by the 11/12Z
HREF which suggests a 10 percent probability for wind gusts 50+
kts in SE Cochise county this afternoon. As the storms progress
to the northwest, they move into that deeper moist airmass which
shifts the potential from wind to heavy rain. The 11/12Z HREF
3-hr probability-matched mean QPF indicates a 10 percent
probability for rainfall in excess of 3 inches across southern
Cochise and Santa Cruz counties between 2-5 pm MST, expanding
across the eastern half of Pima county and SE Pinal counties
between 5-8 pm MST. Given this, and the deep moisture to the
west that would feed into the storms in the low-to-mid levels,
we decided to expand the coverage of the Flash Flood Watch to
include central Pima county (including the Tohono O'odham
Nation) as well as SE Pinal county. My concern is that as the
upper-high center moves east, the NW progress of the convection
will stall out across the central portions of the CWA late this
evening and stick around through the night. Granted, the
convective complex will continue to weaken, but even moderate
rainfall over the same spot will keep the concern for flash
flooding into the early morning hours.

Otherwise, Wednesday and Thursday still look quite wet as the
flow becomes southerly and any wiggle/disturbance in the flow
will easily result in convection across our neck of the woods.
Re-iterating the previous forecast discussion...expect a downturn
in daily thunderstorm activity Friday into the weekend as drier
air pushes across the area under southwest flow aloft. Isolated
thunderstorms at best, and mostly east of Tucson. Temperatures
will be near normal today, then be about 3 to 6 degrees below
normal Wednesday and Thursday, with warming thereafter to above
normal values for this weekend.

&&

.AVIATION... Valid thru 13/00Z. SCT-BKN 8-12k ft AGL with
widely scattered -SHRA/-TSRA thru 11/22z then scattered to
numerous -SHRA/TS contg thru end of valid pd. Isold vsbys 1SM
+TSRA. Gusty erratic winds of 35-50 kts possible with any
thunderstorm, especially near KDUG this afternoon. Outside of
storms SFC winds WLY/NWLY at 8-12 kts with ocnl gusts to 20 kts
this aftn and evening. SFC winds light and terrain driven after
12/06Z. Aviation discussion not updated for TAF amendments.

&&

.FIRE WEATHER...The combination of a shifting weather pattern aloft
and deep moisture residing across the region will result in
scattered to numerous showers and thunderstorms across Southeast
Arizona with the potential for heavy rain the next few days.
Although most of the storms will produce between a half and one
inch of rain, the stronger storms are capable of producing
locally heavier amounts between 1-3 inches. Otherwise, a drier
southwest flow aloft will bring a downturn in daily storm
activity Friday into the weekend. Minimum relative humidity
will be 20-40 percent through Thursday lowering to around 15-30
percent thereafter. Temperatures will be near normal through
Tuesday, dropping to below normal Wednesday and Thursday, then
warming again next weekend. Outside of thunderstorms, winds
terrain driven to around 10 mph with occasional afternoon gusts
to 20 mph.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
Flood Watch from 2 PM MST this afternoon through this evening
for AZZ502>509-511>515.

&&

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