Catalina Foothills, Arizona 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

246
FXUS65 KTWC 191637
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
937 AM MST Sat Jul 19 2025

.SYNOPSIS...Chance of showers and thunderstorms this weekend into
early next week then drying out. High temperatures around normal
through the weekend into early next week then heating up.

&&

.UPDATE...The upper level flow pattern remains southerly to
southeasterly as we are broadly sandwiched between an elongated,
strengthening upper high stretched over the south central plains and
a weak upper low over southern California. This morning there were a
couple isolated showers across portions of Pinal, Graham, Greenlee,
far western Pima, and northeast Cochise counties with scattered to
broken mid-level clouds moving from south to north across southeast
Arizona. Latest GOES-19 precipitable water estimates range between
1.0" to 1.4" with surface dewpoints in the upper 50s to mid 60s,
sufficient atmospheric moisture residing to support shower and
thunderstorm activity.

Decreasing cloudcover this morning will give way to surface heating
and afternoon showers and storms forming over the mountains this
afternoon across Cochise, Santa Cruz, and eastern Pima counties. I
am not quite as impressed with the upper dynamic support as I was
yesterday, but we do at least have some mid-level diffluence and
weakness that will not necessarily hinder the development of showers
and storms this afternoon. On the other hand, the upper high
centered over the souther plains did cause some warmer air to
reside in the midlevels yesterday which choked off initial
thunderstorms that formed over the terrain. Even modestly cooler
air in the midlevel today could help make the difference in
storm development. We will see more detail in our upcoming 19/18Z
sounding.

The main hazard again today with any sustained stronger cells will
be the threat for heavy rainfall which could lead to localized
instances of flash flooding. The 19/12Z HREF highlights the best
chance (30-50%) for seeing over an inch of rain in a 3-hour window
over Santa Cruz and southern Cochise counties. I do suspect that the
best storms will tend to be anchored over the terrain while other
storms that form in the valleys will need to be outflow driven.

Overall, another low to mid-grade Monsoon day is on tap mainly to
the south and east of Tucson with heavy rainfall potential in the
strongest cells.

&&

.PREV DISCUSSION... /issued 307 AM MST Sat Jul 19 2025/

Infrared satellite imagery this morning showed plenty of debris
cloud cover over the area with radar showing a few light showers.
SE AZ this morning was between an upper low near San Diego and an
upper high near Dallas. Further south there was an inverted trof
over the Mexican states of Durango and Sinaloa.

Today: The debris cloud cover will slowly dissipate through the
morning hours. If dissipation is slower than current thinking
that will delay the start of storm development, which will begin
in the mountains this afternoon, especially south and southeast of
Tucson. Overall looking at similar storm coverage as yesterday. A
few storms along the Intl border will be capable of producing
brief heavy rain into this evening. Highs today similar to what
occurred yesterday.

Tonight: Thunderstorm activity will be much more widespread over
Sonora Mexico with some of these storms potentially moving across
the area during the overnight hours.

Sunday: Per the initialized forecast from the NBM, which may be a
bit too high with the PoPs, may be a bit more active that today
with primary threat being brief heavy rain and gusty winds. Highs
slightly cooler than today.

Next week: Chance of afternoon/evening showers and thunderstorms
Monday and Tuesday then the area drys out as drier SW overspreads
the area through the second half of next week. Highs start the
week below normal then heating up by the end of the week with
potential of hotter temperatures next weekend. Latest NbM
probabilities of 110 degrees for Tucson has 11% chance on Sun July
27th and 18% chance on Mon July 28th.

&&

.AVIATION...Valid through 20/12Z.
Debris cloud cover mainly above 10k ft AGL will gradually
dissipate this morning. Aft 19/18z SCT clouds at 8k-11k feet with
isolated to scattered showers and thunderstorms mainly east and
south of KTUS through this evening. Gusty and erratic winds up to
40 kts with any storm. Otherwise surface winds mainly under 12
kts. Aviation discussion not updated for TAF amendments.

&&

.FIRE WEATHER...High temperatures generally near normal for much
of the next 7 days under a low grade monsoon pattern with
day-to-day variability in thunderstorm coverage. Afternoon winds
will remain westerly from 10-15 mph, with occasional gusts at or
above 25 mph. Afternoon RH values in the low lying areas will be
17-25% this weekend. In the higher terrain, RH will be around 30
to 50%.

&&

&&

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

&&

$$

Update...DVS

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