034
FXUS65 KTWC 041659
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
959 AM MST Fri Jul 4 2025

.SYNOPSIS...A drying trend is expected for today into this
weekend with mainly isolated storm coverage focused on locales
south of Tucson. Temperatures will remain below normal through
Friday before warming back up to above normal levels by Sunday and
continuing through much of next week.

&&

.DISCUSSION...Independence Day is one of those perfect holidays
to get together with family and friends, enjoy your time in the
moment and also reflect on the past. I guess we do the same type
of thing with meteorology. Southeast Arizona has successfully
made its move into the 2025 Monsoon this past week with plenty of
thunderstorm activity the past several days already under our
belt. Not all Monsoon seasons are like that. Some storm activity
kinda trickles into the area over the first half of July.

In any event, we have been advertising a decrease in thunderstorm
activity today into this weekend and it looks like that will hold
tight. The upper pattern this morning is defined by the 500 mb
high center building into Southeast Arizona from the WSW, in the
wake of the departing trough which is currently moving through
the Rockies. The latest GOES PWAT imagery indicated slightly over
an inch of precipitable water acrSct debris clouds will
gradually decrease this morning. oss the southern half of Arizona
this morning. Surface dewpoints are in the lower to mid 60s across
valley locations, but should begin to mix out into the upper 40s
to mid 50s by this afternoon. There is a weak 850-700 mb Theta-E
ridge axis that extends across Sonora Mexico into Santa Cruz
county this morning. Normally, this should be enough moisture for
storms to feed off of today...but the position of the upper high
should should hinder deep convection across the area. At 9 AM MST,
we are seeing quite a bit of CU developing over the higher
terrain. Expect these to start bubbling over the mountains today
as the CU field expands over the valleys early this afternoon.
Storms won`t be non-existant today. Expect isolated to low-end
scattered convection to develop today across mainly Santa Cruz
and SW half of Cochise this afternoon. There is ample moisture to
work with...so the storms will be capable of producing locally
heavy rain today. In fact, the 04/12Z HREF indicates on their 3-hr
ensemble probability matched mean QPF a 30-50 percent chance of
1+ inch of rainfall.

We will see a reinforcement of lower level moisture across our
neck of the woods overnight tonight into Saturday as a weak gulf
surge spill into the lower deserts of SW Arizona. Despite the
increase in moisture across the Western portions of the forecast
area, The coverage of thunderstorms Saturday will also be limited,
with the focus for storms shifting a little farther west into
Santa Cruz county into the Tohono O`odham Nation.

The 500 mb high is expected to slowly drift northward into NE AZ
Sunday into the first half of next week. Although this seems like
a subtle shift, this does change the direction of the flow from
the SW to a more divergent NE flow, which is more conducive for
thunderstorm activity Monday thru Wednesday. The only downside is
that this will also lift the 300 mb high into WRN AZ. This will
not only limit thunderstorms coverage across the western portions
of thew forecast area, but will also warm us up. The 04/15Z NBM
probabilities of reaching 110 degrees at the Tucson International
Airport (KTUS) are now 17% Tuesday, 41% Wednesday and 24%
Thursday. Nobody is a fan of that. For now, the warm celebrations
with a quiet-ish holiday weekend will have to suffice.

&&

.AVIATION...Valid through 05/18Z. SCT-BKN 7-12k ft AGL will dvlp
aft 04/19Z. ISOLD-SCT SHRA/TSRA are expected through 04/04Z with
CIGS BKN 5-8k ft AGL and gusty outflow winds up to 40 kts. Surface
winds generally WLY 8-13 kts, becoming SLY less than 10 kts
overnight. Aviation discussion not updated for TAF amendments.

&&

.FIRE WEATHER...Slightly below normal temperatures today, then
warming back this weekend into next week. Expect isolated to
scattered showers and thunderstorms this afternoon into this
evening mainly south and southeast of Tucson. A decrease in
thunderstorm activity is expected this weekend as the area
transitions into a low grade monsoon pattern. An eventual uptick
in monsoon activity is possible the middle of next week but will
be dependent on how quick the high pressure aloft shifts north.
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...None.

&&

$$

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