688
FXUS65 KTWC 062007
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
107 PM MST Sun Jul 6 2025

.SYNOPSIS...Expect isolated to scattered storm coverage today
focused on locales generally south and southeast of Tucson. The
main hazard from the storms today will be their capability to
produce strong gusty outflow winds. Otherwise, temperatures will
be above normal this week with the potential for extreme heat to
return to Southeast Arizona by the middle of the week.

&&

.DISCUSSION...A slow start to storm development today across
Southeast Arizona as the latest satellite imagery indicated
mostly sunny skies across the forecast area with a few buildups
over the higher terrain. The upper pattern is defined by an upper
high extending across Sonora Mexico into southern New Mexico. The
500 mb high center shifts ever-so-sligtly into western Sonora
this afternoon, resulting in a very weak diffluent flow across
Santa Cruz and Cochise counties this afternoon. This very subtle
shift this time of year is one of the factors that help initiate
and assist convection. The deeper moisture that was in place
yesterday has shifted west, with the latest GOES TPW imagery
indicating 1.25-1.40 inches across western Pima county, around
1.00-1.25 inches near the Tucson Metro Area, and lower values of
0.95-1.05 inch across Cochise/Graham and Greenlee counties. This
matches up with the 06/18Z KTWC upper air sounding that indicated
a PWAT of 1.24 inches.

Given the lower atmospheric moisture, the 06/12Z HREF members are
suggesting the majority of the storms today will be across Santa
Cruz into Cochise county with a 10-30% chance for 3-hr ensemble
probability matched mean values (40-km neighborhood probability)
exceeding an inch confined to Santa Cruz/SW half of Cochise
counties. The drier air does bring back the potential for
evaporating downdrafts resulting in strong outflow winds with
around a 50 percent chance that outflows will exceed 30kts this
afternoon across the same area. The 06/18Z sounding was not very
excited about strong storms today with a very pronounced warm
layer AOA 550 mb choking off the tops of the storms. I have backed
off of the high-scattered pops given with the NBM this afternoon,
pairing them back to isolated with low-end scattered along the
International Border.

As mentioned in the previous forecast discussion...the main theme
this week will be an expanding strong ridge of high pressure aloft
over the state resulting in very hot, near record high temperatures
mid-week and a low grade monsoon pattern. The high centers continue
to drift north the next few days, resulting in stacked mid and
high level highs Wednesday. Not much variation in 06/19Z NBM
ensemble members Wednesday with only a 1 degree variation (110-111
degrees) between the 25th-75th percentile at KTUS. The overall
probability of exceeding 110 degrees at KTUS is 6% Tuesday, 77%
Wednesday and back down to a 19% Thursday. Solid confidence in the
Extreme Heat Watch in effect for Pima, SE Pinal and Graham
counties Wednesday so we decided to upgrade it to an Extreme Heat
Warning.

We will see the upper high shift the second half of the week into
the weekend resulting in a general uptick in thunderstorm coverage,
especially across the eastern half of our forecast area. The 500
mb high center is now progged to shift into southern California by
Saturday and sit there for a while. This location will allow for
a more diffluent upper flow across the eastern zones driving
storms that develop in the Whites and along the AZ/NM border SSW
into northern Sonora. Its not a favored location for the more
active rim-shot pattern for storms to drive SW into Tucson, but I
suspect that large day-to-day thunderstorm complexes will develop
in Sonora, reinforcing the surface moisture back into Southeast
Arizona with their outflows and eventually having a hand in
nudging the upper high centers back toward northern Arizona.

Until then, expect a low-grade Monsoon pattern to persist with
afternoon high-temperatures moving into the very hot/record high
temperature range Wednesday.

&&

.AVIATION...Valid through 08/00Z. SKC to FEW 10-12k ft AGL thru
06/19Z then SCT-BKN 7-12k ft AGL with ISOLD-SCT -SHRA/-TSRA mainly
S/SE of KTUS thru 07/04Z with CIGS BKN 5-8k ft AGL and gusty
outflow winds up to 45 kts. Skies will then become SKC-FEW 12-15k
ft AGL overnight, then SCT-BKN 7-12k ft AGL again Monday afternoon.
Surface winds generally WLY 8-13 kts, becoming SLY less than 10
kts overnight. Aviation discussion not updated for TAF amendments.

&&

.FIRE WEATHER...Although Southeast Arizona will be experiencing a
low-grade monsoon pattern the first half of the week, isolated to
low-end scattered thunderstorm coverage is expected to the south
and southeast of Tucson for the next several days. The main threat
for storms will be the potential for strong gusty and erratic
outflow winds. Otherwise, an eventual uptick in monsoon activity
is possible the second half of the week into next weekend as the
upper high shifts to a more favorable location aloft. Temperatures
will be above normal this week with hottest temperatures mid-week.
Winds generally light and under 15 mph with the exception of
gusty and erratic winds up to 35-45 mph near any thunderstorms.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...

Extreme Heat Warning from 10 AM to 8 PM MST Wednesday for
AZZ501-502-504>506-509.

&&

$$

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