839
FXUS65 KTWC 171005
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
305 AM MST Thu Jul 17 2025

.SYNOPSIS...Low-grade monsoon pattern through the weekend with
high temperatures around normal.

&&

.DISCUSSION...Infrared satellite imagery this morning showed
considerable cloud cover west of Tucson into SW AZ associated an
MCV. Water vapor imagery showed upper low near the Baja Spur
lifting slowly to the north. PWAT values this morning, per
GOES-19, ranged from 0.90" to 1.40" with the drier air over Santa
Cruz county. At the surface dewpoints were in the upper 50s to
upper 60s.

Today: The Baja Spur upper low will continue to lift slowly north
with southerly flow over the area. Low grade monsoon day with
mostly isolated storms as surface dewpoints mix down into lower to
mid 50s. Better chances of storms in the Whites. Thanks to more
sunshine, highs will run 4 to 9 degrees warmer than yesterday.

Friday: Flow aloft remains southerly with the Baja upper low
near San Diego by early evening. Once again looking at a low-grade
monsoon day with surface dewpoints mixing down into the upper 40s
to mid 50s. Highs around 2 to 4 degrees warmer than today. There
is the potential for a few storms moving into the area during the
overnight hours thanks to outflows from Sonora MX. These outflows
will bring an increase in low-level moisture.

This weekend: Slight uptick in chances of afternoon/evening
storms as we work on recycled moisture. Highs right around normal.

Next week: Chance of afternoon/evening storms each day with no day
sticking out to be more active than the other. Highs right around
normal.

&&

.AVIATION... Valid 18/12Z.
SKC to BKN 8k-10k ft AGL. Isold -SHRA/TS btwn 17/17z and 18/04z.
Gusty and erratic winds up to 40 kts psbl with any of the storms
that dvlp. Otrw, SFC winds mainly less than 10 kts. Aviation
discussion not updated for TAF amendments.

&&

.FIRE WEATHER...Temperatures today cooler than normal than near
normal this weekend into early next week. Low grade monsoon
pattern for much of the next 7 days 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 20-30% through Friday
decreasing to 17-25% over the weekend.

&&

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

&&

$$

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