027
FXUS65 KTWC 210954
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
254 AM MST Thu Aug 21 2025

.SYNOPSIS...Daily chances for thunderstorms and rain showers for
Southeast Arizona with day to day variability on coverage and
intensity. Above normal temperatures through the weekend and then
trending down to near normal by the start of the new week. An Extreme
Heat Warning in effect today through Friday.


&&

.DISCUSSION...Four Corners High is still influencing region per
this morning`s water vapor imagery. The only difference from the
previous 24 hours is the elongated ridge axis from Baja California
to South Dakota. The egg shape high will bring northeasterly flow
across Southeast Arizona today along with drier air moving into
the eastern regions. Storms will initiate along the higher
terrain and move west to southwest across the region. Cochise
County will have drier air, leading to lower chances for rain
showers and thunderstorms. Expect strong and gusty erratic winds
from any thunderstorm. Blowing dust is possible.

Heat is still the hot topic through tomorrow. Low elevations will
be above 100 degrees to 110 degrees with little overnight
reprieve. Those areas will experience Major HeatRisk to isolated
areas of Extreme HeatRisk through Friday. We will be trending down
slightly in temperatures this weekend but areas will be on the
cusp on Major HeatRisk per climatology. For now, we will maintain
the Extreme Heat Warning through Friday evening.

By the weekend, dryer air will push more into the region, but
there will be enough instability and moisture to give daily
chances. Higher terrain will naturally be the better areas for
those rain chances. The Four Corners High will transform itself to
ridge through the Great Basin by the start of the new week. Plus,
troughiness will develop near the Pacific coast. This will open
up southeasterly to southerly flow of deep monsoon moisture back
into the region. Ensemble models show our PAWTs shooting up to
1.4-1.6 inches at Tucson with higher values towards Yuma. This
tongue of moisture will provide better chances and coverage for
rain showers and thunderstorms. As of this forecast, Tuesday
through Wednesday appear to be the wettest days in the forecast
period. Increase moisture will lower our temperatures and leaning
below normal through the new week.



&&

.AVIATION...Valid through 22/12Z.

SKC to FEW clouds AOA 20k ft AGL with across the region this
morning. By 21/18Z, SCT-BKN clouds AOA 8-12k ft AGL with isolated
to scattered -SHRA/-TSRA forming along the higher terrain and
moving westward through 22/06Z. Lingering -SHRA is possible
through 22/10z. SFC winds will generally be easterly-southeasterly
less than 12 kts through the forecast period. Expect gusty and
erratic winds with any -TSRA. Aviation discussion not updated for
TAF amendments.


&&

.FIRE WEATHER...Expect daily chances for rain showers and
thunderstorms into the new week. Dryer air will be moving into the
region to create day to day variability of intensity and
coverage. Temperatures will be running above normal through the
weekend with an Extreme Heat Warning in effect through Friday in
the lower elevations. Winds will generally remain less than 15 mph
with the afternoon gustiness into the new week. Min RHs will be
15-20 percent in the low elevations and 20-30 in the mountains
through the weekend. Deep monsoon moisture will return early next
week to provide higher wetting rain chances and coverage as well
as better min RHs and below normal temperatures.


&&

.TWC WATCHES/WARNINGS/ADVISORIES...
Extreme Heat Warning until 8 PM MST Friday for AZZ501>507-509.

&&

$$

Strongman

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