243
FXUS65 KTWC 021630
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
930 AM MST Wed Jul 2 2025

.SYNOPSIS...Monsoon moisture has arrived in Southeast Arizona.
Scattered to numerous thunderstorm activity develops midday
Wednesday and continues into the evening with a heavy rain and
localized flash flood threat along with gusty outflow winds with
areas of blowing dust. A drying trend is expected for the July 4th
holiday and this weekend with storm coverage more isolated and
focused on locales south of Tucson. Temperatures will drop to near
normal levels today, then below normal to end the week before
warming back up to above normal levels this weekend into early
next week.

&&

.UPDATE...Today is panning out to be a rather active Monsoon
day for portions of southeast Arizona. Multiple ingredients are
coming together to support showers and thunderstorms with the
potential for heavy rainfall and gusty winds. The Weather Prediction
Center has put us in a slight risk for excessive rainfall today and
a Flash Flood Watch is in effect from 11 AM this morning through 11
PM this evening for T.O. Nation, eastern Pima, Santa Cruz, and
western Cochise county. Any stronger storms that form will have
outflows with gusty and erratic winds between 35-45 mph which could
reduce visibility to below a mile at times.

Upper level divergence combined with low-level moisture convergence
both maximized over eastern Pima county will result in widespread
shower and thunderstorm development this afternoon. Latest GOES-19
satellite imagery depicts 1.0 to 1.5 inches of precipitable water
across the area and dewpoints have surged into the mid 50s to low
60s at the time of this writing. Plenty of surface and deeper
moisture to work with compared to the last few days.

The 12Z HREF and UAWRF continue to support previous shift thinking
depicting thunderstorm initiation around midday from the Tucson
Metro southward into Santa Cruz County with outflows gradually
pushing west across T.O. Nation and northwest across Pinal county.
HREF 40-km 3-hour neighborhood probabilities for heavy rainfall
continue to be maximized depicting a 50-70 percent chance of 1 inch
or more across southeast Arizona with a 10 percent of 3 inches or
more over Santa Cruz, eastern Pima, and southwest Cochise county
aligning well with the Flash Flood Watch. In addition to the heavy
rainfall threat, gusty and erratic outflow winds cannot be ruled
out, especially with any of the stronger cells. HREF 40-km 4-hour
maximum neighborhood probabilities for winds over 30 knots (35 mph)
is maximized at 70 percent across Pinal, Santa Cruz, and
eastern/central Pima County with a 10 percent chance for winds in
excess of 50 knots (60 mph) over Pinal County. This aligns well with
the current Blowing Dust Advisory in effect from 1 PM to 7 PM for
those areas.

&&

.PREV DISCUSSION... /issued 246 AM MST Wed Jul 2 2025/

An active Wednesday is shaping up for much of our forecast area.
In the very near term, we still have some leftover convection
early this morning generally across the T.O. Nation into Pinal
County. These showers and embedded thunderstorms are producing
locally heavy downpours. The CAMs have struggled to pickup on this
activity that is being driven by a combination of residual
outflows, mid level stretching deformation and upper level
divergence ahead of a trough near the southern California coast.
We anticipate this activity will gradually subside over the next
few hours.

Things are still on track for a busy monsoon day today. We`re
continuing to see an increase in lower level moisture from Sonora
and the Gulf of California with surface dewpoints generally in the
mid 50s and PWATs ranging from about 1.1 to 1.4 inches. HREF and
UofA WRF CAMs are in good agreement that we`ll see convective
initiation around midday from the Tucson area southward into Santa
Cruz County and then spreading outward from there off of outflows as
individual storms tend to move slowly towards the west. The Flash
Flood Watch previously issued continues to look good with 50-90%
HREF 40-km 3 hour neighborhood probabilities of 1 inch or more from
the Tucson area southward, and 10-20% neighborhood probabilities of
3 inches or more in Santa Cruz and south central Pima county. We
also went ahead and hoisted a Blowing Dust Advisory from 1 PM to 7
PM for the Tucson Metro, T.O. Nation and south-central Pinal County
as DCAPE values remain elevated at around 1000-1500 J/KG. These
values are sufficient to create strong outflow winds to produce
blowing dust out ahead of the heavier rain cores. While the bulk of
the stronger storms will be during the afternoon into early evening,
shower activity with some embedded thunderstorms could persist into
the overnight hours tonight.

While PoPs remain elevated on Thursday in the 30-60% range, if the
activity today ends up being as widespread as expected, the
atmosphere will be a bit worked over reducing the heavy rain threat
compared to today.

A more pronounced drying trend will commence on Friday as the
combination of drier air aloft and high pressure centered to our
south will result in much diminished shower and thunderstorm
activity. Most locales will stay dry for July 4 celebrations with
the highest PoPs around 15-30% from Tucson southward.

For the weekend, a drying and warming trend with no mentionable PoPs
by Sunday as high pressure aloft builds across the region bringing
back hotter temperatures. Ensembles show the high nudging back
northward next week which should reintroduce southeast AZ back into
more favorable east to northeast flow to return some moisture.

&&

.AVIATION...Valid through 03/12Z. SCT-BKN 7-12k ft AGL from KTUS
westward thru 02/13Z, otherwise SCT-BKN 12-15k ft AGL early this
morning, then SCT-BKN 5-10k ft AGL aft 02/18Z thru the end of the
valid period. Scattered to numerous SHRA/TSRA will occur mainly
02/18Z-03/04Z with CIGS BKN 5-8k ft AGL. Storms that develop this
afternoon and evening will also produce gusty outflow winds greater
than 35 kts with reduced visibility due to localized BLDU. Aviation
discussion not updated for TAF amendments.

&&

.FIRE WEATHER...Near to slightly below normal temperatures through
Saturday as deeper atmospheric moisture moves into Southeast
Arizona, then warming back up Sunday into early next week. Expect
scattered to numerous showers and thunderstorms this afternoon into
evening with locally heavy rainfall. Shower and thunderstorm chances
persist Thursday, then some drying will tend to lower thunderstorm
chances to around 15 to 30 percent Friday into the weekend with the
highest chances along the Int`l border. 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...
Flood Watch through this evening for AZZ502>504-507-513>515.

Blowing Dust Advisory from 1 PM this afternoon to 7 PM MST this
evening for AZZ502-504-505.

&&

$$

UPDATE...DVS

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