Flash Flood Warning 132, NWS Tucson, AZ

Area Forecast Discussion
National Weather Service Tucson AZ
312 PM MST Wed Aug 12 2026

.SYNOPSIS...A shifting weather pattern will support scattered
showers and storms the next few days. The strongest storms could
produce heavy rainfall and flash flooding with rainfall rates around
three quarters of an inch to an inch and a half per hour. Storm
activity will clear out Friday into the weekend bringing warmer and
drier conditions and moderate HeatRisk.

&&

.DISCUSSION...Cloud cover led to a pleasant morning with lows in the
60s and 70s across southeast Arizona. There were a few lingering
showers and storms from overnight convection. Overall, we saw a
slowdown in the convective activity through the morning hours. Now,
we start to see a ramp up again with showers and storms so far
forming mainly south and east of Tucson in the White Mountains.

The atmospheric environment this afternoon favors isolated to
scattered storms capable of producing moderate to heavy rainfall.
The Weather Prediction Center has Graham, Greenlee, Cochise, Santa
Cruz, Pinal, and eastern Pima counties in a slight risk for
excessive rainfall that could lead to flash flooding. Hourly
rainfall rates could be between 0.75 to 1.5 inches per hour, which
would be enough to result in localized instances of flash flooding.

As a upper level trough approaches the area from the west coast,
flow will become more southwesterly promoting lift and another round
of nocturnal showers and thunderstorms from late tonight into early
tomorrow morning mainly north and east of Tucson. Cannot rule out
isolated flash flooding over Graham/Greenlee and Pinal counties with
this activity.

For the remainder of the work week into the weekend we will see a
gradual downturn in the coverage and intensity of showers and
storms. Not to say that we won't have any activity at all, but we
start to minimize the necessary ingredients for widespread showers
and storms. We lose our lift provided by the upper level trough
which will usher dry air aloft into the region. Any storms that do
form will be from recycled moisture in the boundary layer (low
levels) of the atmosphere. The best chances (10-30%) will be mainly
for areas east and south of Tucson.

Early next week chances for showers and storms may return as an
easterly wave moves over northern Mexico. This would bring some
moisture and dynamics back into play supporting an uptick in storm
activity. But we could also see the moisture slow to return and
temperatures warming up into 105 territory for the Tucson Metro.

&&

.AVIATION...Valid through 14/00Z.
SCT-BKN 7-11k ft AGL thru much of the valid pd. SCTD -SHRA/-TSRA
with isold vsbys 1SM +TSRA. Gusty erratic winds of 35-45 kts
possible with any thunderstorm. Outside of storms SFC winds WLY/NWLY
at 8-12 kts with ocnl gusts to 20 kts. SFC winds light and terrain
driven between 13/06Z and 13/16Z. Tomorrow, chances for showers and
storms again mainly east of KAVQ to KOLS line. Aviation discussion
not updated for TAF amendments.

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.FIRE WEATHER...The combination of a shifting weather pattern
aloft and deep moisture residing across the region will result in
scattered showers and thunderstorms the next couple days across
Southeast Arizona with the potential for heavy rain. 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
below normal today and Thursday, then warm up again for the weekend.
Outside of thunderstorms, winds terrain driven to around 10 mph with
occasional afternoon gusts to 20 mph.

&&

.HYDROLOGY...Early this morning the Vamori Wash near the village of
Santa Cruz in central Pima County showed a significant rise, topping
out near flood stage. A Flood Advisory remains in effect until 4 pm
MST near the village of Santa Cruz on Tohono O'odham Nation in
central Pima County. We are also keeping an eye on the Santa Cruz
River near Tubac and the San Pedro River near Palominas for
potentially heavy rainfall that could support significant rises.
Right now, these points are forecast to remain below action stage.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...None

&&

DVS

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