761
FXUS65 KTWC 300951
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
251 AM MST Mon Jun 30 2025

.SYNOPSIS...Very hot today with the hottest temperatures of this
stretch. An Extreme Heat Warning is in effect for portions of
southeast Arizona. Monsoon moisture increases this week with the
main threats today and Tuesday being gusty winds and blowing dust,
then transitioning to a locally heavy rain and isolated flash
flooding threat with continued gusty wind potential Wednesday and
Thursday. While shower and thunderstorm chances continue
Independence Day and the weekend, coverage is expected to decrease.
Temperatures will drop to near normal levels Wednesday, then below
normal to end the week.

&&

.KEY MESSAGES...

-Temperatures peak today with highs of 108 to 114 degrees in the
deserts including Tucson and Upper Gila River Valley. An Extreme
Heat Warning is in effect from 10 AM to 8 PM for these locales.

-Temperatures will drop to near normal levels Wednesday, then
 below normal to end the week

-Isolated to scattered showers and thunderstorms mainly east of
Tucson today, then from Sells eastward Tuesday. Main threats today
and Tuesday will be gusty winds, blowing dust and dry lightning
potential as these thunderstorms won`t produce much in the way of
rainfall.

-Wednesday and Thursday, as more abundant moisture moves in, storms
will have wind and locally heavy rain threats along with isolated
flash flooding potential. Storms will be focused on locales
from Sells eastward.

-Shower and thunderstorm chances continue Independence Day and this
weekend but less coverage compared to Wednesday and Thursday as a
lower grade monsoon pattern develops.

&&

.DISCUSSION...An active week for southeast Arizona as monsoon 2025
ramps up. First, let`s talk about the Extreme Heat today as we
typically have a bout of very hot temperatures before the monsoonal
moisture comes in full force and this year is no exception. Today
will be the hottest day with a forecast high of 111 degrees in
Tucson. This is just below the daily record of 112 (1989). An
Extreme Heat Warning remains in effect today for Pima, SE Pinal and
the Upper Gila Valley region of Graham County. A downward trend in
temperatures starts Tuesday with significant cooling and well below
normal temperatures by Thursday.

The mid/upper level high responsible for the hot temperatures is
shifting to northeast AZ today and that is opening door for moisture
to move in from the east. Moisture levels today are typical for an
early season transition day as PWAT values are just high enough (0.7-
1 inch) for very high based convection. This will generally be
focused on locales across Graham/Greenlee/Cochise/Santa Cruz
counties where isolated to scattered convection will develop this
afternoon. With DCAPE values at 1500-2000+ J/KG we are concerned
about dry microburst potential with any storms that develop. The 00Z
HREF continues to show 40km neighborhood probabilities of 70 to 90
percent of wind gusts greater than 30 kts across
Graham/Greenlee/Cochise Counties late this afternoon and early
evening with a 10 to 30 percent chance of 50 kts. Note that due to
the lack of wetting rains with the convection, especially away from
the NM border, some of this activity will be accompanied by dry
lightning. Blowing dust from outflow winds will also occur in
susceptible locales. Tucson is on the western edge of convective
activity potential late this afternoon and this evening, however,
gusty outflow winds are expected to move in from the east or
northeast this evening bringing with it an additional push of
moisture.

As PWAT values increase by Tuesday morning to around 1 to 1.1 inches
and corresponding surface dewpoints jump into the 50s that will set
the stage for an expansion westward of shower and thunderstorm
chances compared to today. The main threats on Tuesday will be
similar to today with regard to strong and gusty winds with blowing
dust potential due to a continued deep mixed layer with hot surface
temperatures and elevated DCAPE values (~1500 J/KG). However, with
increased moisture there will be more in the way of wetting rainfall
underneath the storm cores areawide.

For Wednesday and Thursday a much more robust moisture push moves in
with the aid of a Gulf Surge and deep moisture moving north from
Sonora. Ensemble means have backed off slightly on PWAT levels
during this time compared to 24 hours ago but still highly confident
of widespread 1.2 to 1.4 inches with brief periods up to around 1.6
inches. These values are much more typically seen during the peak of
the monsoon. With weak steering flow on Wednesday as the trough to
our west won`t have much influence yet, some of the storms will be
capable of producing locally heavy rain and isolated flash flooding.
The aforementioned trough axis will then move through the state
Thursday into Thursday night, likely providing a bit more lift for
as the steering flow becomes more west to southwest. This type of
pattern would result in the bulk of the thunderstorm activity from
Tucson eastward but still considerable uncertainty remains in the
details.

With westerly flow on Friday and the high briefly retreating to our
south to southeast, the atmosphere will dry out a bit compared to
Wednesday and Thursday which will reduce thunderstorm coverage.
However, shower and thunderstorm chances are still in the 20 to 40
percent range for much of southeast Arizona with the highest PoPs
along the International border. PWAT values will drop down to around
1 inch this weekend resulting in more isolated storm coverage.

&&

.AVIATION...Valid through 01/12Z.
Generally SKC this morning then SCT-BKN clouds 8-13k ft AGL from
30/19Z thru 01/06Z and then diminishing thru the end of the valid
period. Sfc winds light and variable this morning, then becoming
WLY/NWLY for KTUS/KOLS westward at 6-10 kts while remaining ELY/SELY
for KDUG. Sfc winds become ELY at 10-15 kts with gusts 20-25 kts for
all terminals aft 01/03Z thru the end of the valid period.
Additionally, expect isolated -SHRA/-TSRA between 30/20Z to 01/03Z
east of KTUS. Storms that develop will produce gusty outflow winds
greater than 30 kts with reduced visibility due to localized blowing
dust. Aviation discussion not updated for TAF amendments.

&&

.FIRE WEATHER...Hot today with minimum relative humidities from 10
to 20 percent. There is enough mid level moisture for isolated to
scattered mainly dry thunderstorms especially across Cochise, Graham
and Greenlee Counties this afternoon and this evening. These will
produce gusty outflow winds up to around 50 mph. As additional
moisture moves in Tuesday, min RH`s increase to 15 to 30 percent
with isolated to scattered showers and thunderstorms for most of
southeast Arizona. There will be an increase in wetting rain under
the storm cores Tuesday compared to today. Even higher moisture
levels move in for Wednesday and Thursday when some of the
thunderstorms have the potential for locally heavy rain. Some drying
will tend to lower thunderstorm chances to around 20 to 40 percent
Friday into the weekend.  Winds generally light and under 15 mph
with isolated gusts up to around 50 mph in/near any thunderstorms.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
Extreme Heat Warning from 10 AM this morning to 8 PM MST this
evening for AZZ501-502-504>506-509.

&&

$$

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