Severe Thunderstorm Warning 28, NWS Tucson, AZ

Area Forecast Discussion
National Weather Service Tucson AZ
1236 PM MST Tue Jul 15 2025

.SYNOPSIS...

Shaping up to be an active monsoon day, with flash flooding and
potential for blowing dust as the primary threats.

&&

.KEY MESSAGES...

- An average to above average grade monsoon day is forecast for
  today. Heavy rain and the potential for flash flooding is the
  primary threat, mainly for eastern Pima (including Tucson),
  Santa Cruz, and Cochise Counties.

- Monsoon activity tomorrow and Thursday will likely depend on
  what happens each of the previous days. Uncertainty in the
  forecast overall is high.

- Temperatures will generally be within a few degrees of normal,
  with low to moderate HeatRisk.

&&

.DISCUSSION...

Light convection has already started to form over portions of
Graham and Greenlee Counties and the Huachucas. This is fairly
consistent with recent HiRes model forecasts. Expecting the
activity to ramp up in the coming hours as daytime heating allows
for more energy buildup to be realized. As storms continue to move
off of the higher terrain, they'll move into a more favorable
environment both to the southeast in with CAPE values exceeding
1000 J/kg and available moisture from Tucson southward.

The primary threat today will be heavy rainfall and the potential
for flash flooding. With such dry conditions the past several
months, areas with slower moving thunderstorms should expect to
see water overrunning low lying areas and roads.

Thus, there is a Flash Flood Watch in effect for portions of
Pima, Cochise, Santa Cruz through this evening in concert with the
Slight Risk of Excessive Rain forecast from WPC.

Have a plan when it comes to encountering flash flooding. Turn
around, don't drown.

Lastly, for the rest of today, blowing dust is also a concern
across the Willcox Playa and north of Tucson near Picacho. Gusty
outflows from stronger downdrafts may kick up dust and cause
temporary visibility issues.

Forecasts for beyond today, primarily for Wednesday and Thursday,
will be more complicated, as the weather will depend on what
happens the previous day. Based on prior experience, active days
can inhibit widespread activity on following days. At this stage,
the forecast reflects average grade monsoon days, but with a high
degree of uncertainty. A drier period is likely to set in at some
point in the next week, but it is highly uncertain when this will
be. This is because there is low predictability in the evolution
of a closed upper low off the Baja coast over the next several
days.

There will be some day to day variability in high temperatures
over the next week, but generally expect them to be within a few
degrees of normal for this time of year.

&&

.AVIATION...

SCT-BKN 7-12k ft AGL through the period. Another round of SCT
TSRA/SHRA is expected aft 15/20Z for much of southeast Arizona.
Wind gusts of 40-50 kts with 1-3SM VSBY in BLDU are possible with
the thunderstorms today, especially near KSAD. Otherwise, SFC
winds mainly less than 10 kts. Aviation discussion not updated for
TAF amendments.

&&

.FIRE WEATHER...

A more active monsoon pattern this week. Deeper atmospheric
moisture moving into the will increase the potential for heavy
rainfall and localized flash flooding, especially today.
Temperatures will remain above normal through today, then drop
back down to near or slightly below normal by mid week. Winds will
remain westerly from 10-15 mph, with occasional gusts at or above
25 mph, and gustier in and around thunderstorm activity.
Afternoon RH values in the low lying areas will be between 10-15%
this afternoon, then 20-30% through the remainder of the week.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
Flood Watch until 11 PM MST this evening for AZZ502>504-507-508-
512>515.

&&

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Aviation...Singer/Dang
Fire Weather....Singer/Dang

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