Severe Thunderstorm Warning 57, NWS Tucson, AZ

Area Forecast Discussion
National Weather Service Tucson AZ
1231 PM MST Mon Aug 25 2025

.SYNOPSIS...Expect daily chances for showers and thunderstorms
with day to day variability on coverage and intensity through mid
week with a drying trend later in the week. Above normal
temperatures through today then trending down to slightly below
normal Tuesday through Thursday.

&&

.DISCUSSION...Showers and thunderstorms are starting to develop
right on schedule across Santa Cruz County. The 18Z KTWC sounding
came in with a PWAT of 1.43 inches and modest instability and just a
bit of a cap to work through. PWATs generally range from 1.2 inch to
1.7 inch range from Tucson westward, while drier air is hanging on
east of Tucson across Graham/Greenlee/Cochise Counties where PWATs
are around 0.8 to 1.2 inches. The convection now developing will
quickly expand to the north and west through the afternoon.
Convection will be aided by divergence out ahead of an upper level
trough over Sonora. MLCAPE values of 1000-1500 J/KG with DCAPE of
around 1000-1300 J/KG. While individual storm motions will be around
15 kts to the west and northwest, 20-25 kts of 0-6km bulk shear will
help support multi-cellular storms and development of a larger cold
pool capable of producing strong outflow winds. As additional
moisture continues to feed in today, flash flooding is a threat as
well, especially with merging cells/clusters. A Flash Flood Watch
from Tucson westward and a Blowing Dust Advisory are in effect this
afternoon into early evening. Meanwhile, for Graham/Greenlee/Cochise
Counties, given the drier air mass in those locales, thunderstorm
activity will not be nearly as widespread. While the main cluster of
storms should exit our area this evening, we can't rule out a few
lingering showers overnight.

The flow will be more southerly on Tuesday compared to today with
still some semblance of mid level troughing just to our south. If
the forecast remains on target for today, much of the central and
western portions of our forecast area will be worked over with the
potential for showers and a few embedded thunderstorms while the
focus for deeper convection will be from Tucson eastward into
Graham/Greenlee/Cochise Counties which won't see as much activity
today. Temperatures will drop to around 3 to 6 degrees below normal
Tuesday.

As the flow becomes more southwesterly Wednesday with the
subtropical high slipping to our southeast, that will promote a
drying trend compared to today and Tuesday with contined below
normal temperatures. This southwest flow will continue Thursday and
Friday, though we'll have to watch for any additional mid level
moisture increase off of TS Juliette well to the west of Baja. The
best chances for showers and thunderstorms is expected to remain to
the south and east of Tucson Thursday into the weekend. By late in
the weekend, the flow tries to become more southerly to
southeasterly again and this could help expand precipitation chances
further west but confidence is low. Temperatures will warm back up
to near or slightly above normal levels Friday through the weekend.

&&

.AVIATION...Valid through 27/00Z.
SCT-BKN 9k-12k ft AGL. Widely scattered SHRA/TSRA from KOLS/KTUS
westward moving NW/W now thru 26/03Z. Expect gusty and erratic winds
with any TSRA outflow with possible BLDU reducing visibilities to
1/4-1 mile. SFC winds will generally be E-SE less than 12 kts from
26/03Z thru 26/19Z. Otherwise, sfc winds mainly WLY/NWLY with the
exception of locales near the NM border. Aviation discussion not
updated for TAF amendments.

&&

.FIRE WEATHER...Expect daily chances for rain showers and
thunderstorms through mid week with diminishing chances later in the
week into next weekend. Temperatures will be running near to
slightly below normal this week. Winds will generally remain less
than 15 mph with the afternoon gustiness this week. Min RHs will be
30-40 percent in the low elevations and 40-60 percent in the
mountains through Thursday then Min RHs drop to 15-25 percent in the
low elevations and 20-35 percent in the mountains through the
weekend.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
 Flood Watch from 1 PM MST this afternoon through this evening   for
AZZ501>505-514-515.

 Blowing Dust Advisory from 1 PM to 5 PM MST this afternoon for
AZZ502-504-505.

 Blowing Dust Advisory from 4 PM this afternoon to 7 PM MST this
evening for AZZ501.

&&