539
FXUS65 KTWC 190936
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
236 AM MST Wed Aug 19 2026

.SYNOPSIS...Strong thunderstorms will return to Southeast
Arizona today. The primary concern with storms today is that
they will be capable of producing organized storm outflow winds
to 45-55 mph, potentially producing localized dense blowing
dust. Deep moisture moving into the region from the Gulf of
California will bring about a secondary concern of heavy
rainfall capable of producing isolated flash flooding,
especially across central and eastern Pima county. Otherwise,
an uptick in storm strength and coverage into the upcoming
weekend. Hot conditions will persist this week with an Extreme
Heat Warning in effect today through Friday for portions of the
Southeast Arizona.

&&

.DISCUSSION...The combination of ample moisture moving into
Southeast Arizona from the Gulf of California and a more
favorable weather pattern aloft will result in an active
Monsoon thunderstorm day across all of Southeast Arizona.
Expect storms to initially develop over the Gila National Forest
of New Mexico and the higher terrain of northern Graham and
northern Greenlee counties around mid-day, then drive southwest
toward the valleys of Southeast Arizona through the afternoon,
then across central and western Pima county this evening. The
primary concern with storms today is that they will be capable
of producing organized storm outflow winds to 45-55 mph,
potentially producing localized dense blowing dust. A Blowing
Dust Advisory is in effect from 3 PM MST this afternoon through
10 PM MST this evening for the western portions of Southeast
Arizona. Deep moisture moving into the region from the Gulf of
California (gulf surge) will bring about a secondary concern of
heavy rainfall capable of producing isolated flash flooding,
especially across central and eastern Pima county.

The upper pattern this morning is defined by a 500 mb high
center over NW AZ, and a SW-NE tilted 500-300 mb ridge axis
extending from the NRN Baja Peninsula northeast into NW AZ.
This ridge axis will move into NRN Arizona today and become
oriented along a W-E axis. This will result in a modest area of
deformation/lift aloft along a general axis extending from
Safford to Sells. In addition, the latest GOES precipitable
water imagery indicated a gulf surge was making its way into SW
AZ this morning, with PWAT values between 1.50 and 1.75 inches
across central and western Pima/WRN Pinal and Maricopa counties.
Surface dewpoints have been on the increase west of Tucson,
with values ranging from the mid 60s to lower 70s. An even
deeper area of moisture with PWATs values between 1.80 and 2.00
inches was currently in the NRN gulf of California, and should
advect into the lower deserts through the day today. With the
strong heating the past several days along with this deep
moisture, MUCAPEs between 1500-2000 J/kg will be available
across the western half of SE AZ this afternoon. The drier sub-
cloud layer SE and S of Tucson today will initially provide the
opportunity for strong outflow winds of 45-55 mph. These
outflows will generally kick to the west and northwest into the
evening. Given the high CAPEs available, these boundaries will
initiate additional convection along them with new development
re-inforcing the outflows. This is supported by the 19/00Z HREF
with 10-20% neighborhood probabilities of storms outflows 50+
kts across Santa Cruz/central and ERN Pima and SE Pinal counties
between 3-10 PM MST. Given this, we thought it would be
necessary to hoist a Blowing Dust Advisory for dense blowing
dust and the potential for a haboob formation this afternoon
impacting mainly Pima and SE Pinal counties.

The NWLY/WLY flow in the lower-mid levels will push this deeper
moisture into the mid-levels of storms today, increasing the
potential for heavy rainfall across central and eastern Pima
counties (including the Tohono O`odham Nation and the Tucson
Metro Area). Coordinated with the WPC this morning to elevate
these areas into their SLGT category on their Day 1 Excessive
Rainfall Outlook (ERO) for today.

Otherwise, we will remain in an active weather pattern into the
weekend as the upper high center moves toward the Four Corners
Thursday and Friday, then into the Rockies by Saturday afternoon.
The Monsoon season rolls on.

&&

.AVIATION...Valid through 20/12Z. FEW-SCT 12-15k ft AGL through
19/20Z, then SCT-BKN 7-11k ft AGL BKN-OVC 12-15k ft AGL with
scattered to numerous -SHRA/-TSRA through 20/05Z. Gusty and erratic
outflow winds possible near TSRA with gusts to 40-50 kts. Organized
outflows may produce VSBY less than 1/2SM in BLDU, especially from
KTUS west and northwest. Winds outside of thunderstorms mainly light
and terrain driven. Aviation discussion not updated for TAF
amendments.

&&

.FIRE WEATHER...Strong thunderstorms will return to Southeast
Arizona today. The primary concern with storms today is that
they will be capable of producing organized storm outflow winds
45-55 mph, potentially producing localized dense blowing dust.
Deep moisture moving into the region from the Gulf of California
will bring about a secondary concern of heavy rainfall capable
of producing isolated flash flooding, especially across central
and eastern Pima county. Otherwise, an uptick in storm strength
and coverage into the upcoming weekend. Hot conditions will
persist this week with an Extreme Heat Warning in effect today
through Friday for portions of the Southeast Arizona. Winds
mainly light and terrain driven. Strong, gusty and erratic winds
will accompany thunderstorms. Minimum relative humidities 15-25
percent in lower elevations with 25-35 percent in the higher
terrain.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
Extreme Heat Warning until 8 PM MST Friday for AZZ501-502-
504>506-509.
Blowing Dust Advisory from 3 PM this afternoon to 10 PM MST
this evening for AZZ501>506.

&&

$$

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