244
FXUS65 KTWC 302153
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
253 PM MST Mon Jun 30 2025

.SYNOPSIS...Very hot today with an Extreme Heat Warning 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 until 8 PM MST.

-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...It is a very hot afternoon across all of Southeast
Arizona today. As of 2 pm MST, the temperature at the Tucson
International Airport (KTUS) has hit 108 degrees, with a few more
degrees of heating left in the day. We have been advertising
108-114 degrees in the Extreme Heat Warning for portions of Pima,
Southeast Pinal and the lower elevations of Graham county until 8
pm MST this evening, and that still seems reasonable.

Today is still shaping up to be an interesting day across Southeast
Arizona as it is that first real taste of the Monsoon season. The
upper pattern this afternoon is defined by a 500 mb high centered
over the northeast half of Arizona, with an amplifying ridge of
high pressure at 300 mb across the western half of the state. The
18Z KTWC upper air sounding indicated a dry airmass over the area
with a precipitable water value of 0.78 inches. The latest GOES
TPW indicates values 0.85-0.90 inches residing just east of the
AZ/NM border with a weak plume extending into the Gila River
Valley with the ESE flow there. The position of the 500 mb high
is allowing a tighter surface gradient to develop across SW NM.
Sustained east to southeast winds of 15-20 kts with gusts up to 30
kts have developed across SW NM this afternoon along this
gradient, which will eventually back into the SE corner of AZ late
this afternoon into the overnight hours. This will result in
breezy to locally windy sustained east-southeast winds spreading
across our neck of the woods from the east tonight, which should
help moisten things up over the next 24 hours.

However, until this happens, the lower levels remain dry with
surface dewpoints in the upper 30s-mid 40s (including the eastern
portions of the CWA). Despite the dry low-levels, there is ample
mid-level moisture to our east to allow for isolated to low-end
scattered thunderstorms to develop. The latest radar imagery
indicated convection developing along the Mogollon Rim into the White
Mountains into the Gila National Forest in New Mexico. Look for
these storms to move SSW off the higher terrain into Cochise,
Graham and southern Greenlee counties as we move into the
afternoon and evening hours. Given the dry sub-cloud layer, the
threat for evaporating downdrafts producing damaging outflow winds
is present. In fact...the 30/12Z HREF indicated a 40-km
neighborhood probability of 70-90% that outflow winds will be in
excess of 30+ kts across Cochise, Graham and Greenlee counties,
with a 10-30% chance of gusts 50+ kts. Given the environmental
conditions, we issued a Blowing Dust Advisory for the potential
for blowing dust reducing visibility down to 1/4-to-1 mile,
especially as some of these stronger outflows pass over the
dust-prone Lordsburg Playa just on the other side of the AZ/NM
border along I-10. Expect enhanced outflows along and near the
leading edge of the backdoor frontal boundary moving in from the
east late this afternoon and this evening given additional momentum
transfer to the surface.

I have mainly been talking about the eastern locations of Southeast
Arizona, but the potential also exists for some of the mid-level
moisture/storms to push westward impacting eastern Pima and
Southeast Pinal counties with strong outflows/blowing dust. in
fact, the SPC has moved their area of marginal on their Day 1
convective outlook west today...and now covers eastern Pima
county. My confidence on it significantly impacting areas that far
west is rather low though given how stacked the 500 and 300 mb
highs are as you get farther west. It should be too stable to
reinforce the sfc outflows...but possible none-the-less.

Otherwise, the upper 500-mb high begins to shift northward Tuesday,
resulting in an area of deformation/lift across central Arizona
extending down into south-central Arizona tomorrow. The moisture
that moves into SE Arizona from the east overnight will reduce
the dry microburst potential, but not get rid of it completely.
Given the slightly higher atmospheric moisture available, we will
see rainfall but the nature of the storms will still be more
weighted toward strong potentially damaging thunderstorm outflow
winds.

Deeper atmospheric moisture eventually moves up the Gulf of California
and Sonora Mexico Wednesday into Thursday. This should shift the
nature of storms to more heavy rainfall than damaging wind
threat, similar to the storms you would see later in the Monsoon
season. Ensembles and thus the NBM have paired back the potential
for widespread heavy rainfall, but the threat of heavy
downpours/flash flooding will be present both Wednesday and
Thursday across all of Southeast Arizona, especially from Tucson
south.

We will see thunderstorm activity take a slight downturn Friday
(The 4th of July) and into the weekend before ramping up again
early next week as we shift into a more favorable upper pattern.
But, for now, we can

&&

.AVIATION...Valid through 02/00Z. SCT-BKN clouds 8-13k ft AGL
thru 01/06Z, diminishing overnight then becoming SCT-BKN 7-12k ft
AGL after 01/18Z. Sfc winds WLY/NWLY for KTUS/KOLS westward at
10 kts while remaining ELY/SELY east of KTUS. Sfc winds become
ELY at 15-20 kts with gusts 25-30 kts for all terminals aft
01/06Z thru the end of the valid period. Additionally, expect
isolated -SHRA/-TSRA east of KTUS through 01/05Z east of KTUS.
Storms that develop will produce gusty outflow winds greater than
35 kts with reduced visibility due to localized BLDU. 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 until 8 PM MST this evening for AZZ501-502-
504>506-509.

Blowing Dust Advisory until 10 PM MST this evening for
AZZ507>509.

&&

$$

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