Dust Storm Advisory 21, NWS Tucson, AZ

Area Forecast Discussion
National Weather Service Tucson AZ
211 PM MST Tue Aug 12 2025

.SYNOPSIS...Isolated to scattered thunderstorms generally east
and south of Tucson this afternoon will be capable of strong
thunderstorm outflow winds with the potential for blowing dust
along the Arizona and New Mexico border. Storms will increase in
strength and coverage Wednesday through Friday across the
majority of Southeast Arizona. Otherwise, expect daily shower and
thunderstorm chances into next week with day to day variability in
chances. High temperatures will generally remain above normal
this week, cooling Friday into this weekend.

&&

.DISCUSSION...Our synoptic pattern, as of this writing, has a high
pressure center over northern Arizona with a trough located to the
west over the Pacific Ocean. Northerly to northeasterly winds
aloft has started convection in the White Mountains and this will
continue through the rest of the afternoon. We have 1.04 inches of
precipitable water, that is slightly less than normal
precipitable for this time of year. Still, it is enough to aid in
storm development because of our steep lapse rates, CAPE values
above 1000 J/kg, and DCAPE of 1600-1800 j/kg, especially in
Cochise to the International Border. Good indicators for severe
wind threat for the day. 12Z HREF has 70 percent probability of
greater than 30 kts from Duncan to Sierra Vista with pockets of
stronger gusts this afternoon. Therefore, thunderstorms will
continue to develop and expand south and west, getting close the
edge of Tucson Metro, with the main threats of strong gusty winds,
blowing dust, and moderate brief heavy rainfall.

Thunderstorms and rain showers will diminish in the late evening.
A few model guidances has shown a late night shower in Tucson,
but that is low confidence. An thunderstorm outflow will likely be
needed to get that late night shower. The upper pattern will
shift into a better position to continue the northeasterly flow
and the moisture will stay elevated for the week.

Our dew points will trend up each day with the highest values on
Thursday and Friday. This will bring daily chances for
thunderstorms and rain showers for the region. Model guidance show
the uptick in activity and expanded coverage starting Wednesday.
One thing to keep an eye out (a monsoon tidbit) with the high dew
points and atmospheric moisture, there is potential for storm
development will be delay. Just like kicking the can down the
road. The typical monsoon variability of the up and down days.
With that in mind, Wednesday through Friday will have the highest
chances for rain showers and thunderstorms.

This weekend, the Pacific trough will have moved inland, pushing
the high pressure center to the east. We will start to see
southerly to southwesterly flow. Moisture will lingering around,
but be a tad lower than the previous days. Ensembles models have
mixed solutions on the exact amounts, but they do show the slight
decrease. Thus, daily chances for thunderstorms. On a different
note, temperatures will be trending down to near normal by the
weekend due to the increase thunderstorm activity and lower
thickness values.

&&

.AVIATION...Valid through 14/00Z.
SCT-BKN clouds at or around 8-12k ft AGL with ISOLD-SCT -SHRA/-TSRA
mainly E-NE of KSAD and S-SE of KTUS through 13/05Z. Lingering -SHRA
will be possible in the overnight through 13/10Z. -SHRA/-TSRA
will expand in coverage after 13/19Z through the end of the
period. Gusty erratic winds up to 45 kts near any TS, especially
along the AZ/NM border and the International border in Cochise
county (near KDUG). Otherwise, surface winds should remain below
15 knots with the occasional afternoon gusts up to 20 kts.
Aviation discussion not updated for TAF amendments.

&&

.FIRE WEATHER...High temperatures will remain several degrees
above normal for the first half of the week and then near normal
this weekend. Daily chances for thunderstorms and wetting rains
through the week with daily variability in coverage and intensity.
Wednesday through Friday will have the highest chances and
coverage for wetting rain showers and thunderstorms. Min RHs will
generally be around 15-25 percent in the lower elevations and
20-35+ percent in the mountains through Thursday, increasing
Friday and Saturday as deeper moisture tracks across the area.
Winds will generally be less than 15 mph with typical afternoon
gusts up to 20 mph into next week.

&&

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

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