Special Weather Statement, NWS Tucson, AZ

Area Forecast Discussion
National Weather Service Tucson AZ
1059 AM MST Thu Aug 26 2021

.SYNOPSIS...High pressure will bring hot temperatures through at
least Friday before somewhat cooler readings arrive by early next
week. Isolated thunderstorms can be expected each day, before an
increase in coverage commences this weekend into early next week.

&&

.DISCUSSION...The forecast remains on track, with no changes this
morning.

Current water vapor imagery shows some increase in moisture
across southern Arizona with GOES derived PWATs showing a finger
of higher PWATs on a line from Sasabe through Tucson and into
northern Graham/Greenlee Counties. The HREF supports this quite
well showing the greatest, albeit marginal, instability in these
locations. HRRR develops isolated showers and thunderstorms
this afternoon, which hug the higher terrain. A few will likely
venture into the valleys due to outflow boundaries, but confidence
is low.

For the heat, expect another hot and somewhat humid day across
southern Arizona. Take it easy today and do what you can to
protect yourself/loved ones from the heat.

&&

.AVIATION...Valid through 27/18Z. Isolated -SHRA/-TSRA will
develop east of KTUS and KOLS this afternoon and into the evening.
FEW-SCT clouds are expected to develop at 8k-12k ft agl this
afternoon with decreasing coverage overnight. Winds will favor a
northwesterly component this afternoon, remaining around 10 knots
before decreasing this evening. Expect similar winds tomorrow.
Aviation discussion not updated for TAF amendments.

&&

.FIRE WEATHER...Isolated thunderstorms will be possible each
afternoon primarily east and south of Tucson and over the higher
elevations the next couple of days. An upswing in thunderstorm
activity will be possible this weekend into early next week.
Temperatures will remain above normal through at least Friday with
triple digit readings expected for much of the lower deserts. 20-
foot winds will generally be less than 15 mph when not influenced by
thunderstorms and RH values are expected to remain above critical
thresholds.

&&

. PREVIOUS DISCUSSION...Excessive heat in the lower deserts can
be expected again today and Friday. Thunderstorm coverage will
continue to be limited in the afternoon and evening hours through
Friday. Thereafter, a more interesting weather pattern evolves
next week as deeper moisture advances northward into the region in
association with a tropical system. The latest NHC forecast
showed tropical depression Fourteen-E tracking toward Baja
California and becoming a hurricane by Saturday or Saturday night.
The current track showed the system passing near the Baja Sur as
a hurricane early next week. That said, will need to watch the
system's evolution the next several days as it will play a
significant role in the weather early to mid next week. Overall,
will see an upswing in shower and thunderstorm activity next week
along with a cooling trend.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
Excessive Heat Warning until 8 PM MST Friday for AZZ501-502-
504>507-509.

&&

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Special Weather Statement
National Weather Service Tucson AZ
217 PM MST Thu Aug 26 2021

AZZ507-514-262200-
Santa Catalina and Rincon Mountains including Mount
Lemmon/Summerhaven-Upper San Pedro River Valley including Sierra
Vista/Benson-
217 PM MST Thu Aug 26 2021

...A strong thunderstorm will impact portions of eastern Pima and
northwestern Cochise Counties through 300 PM MST...

At 217 PM MST, Doppler radar was tracking a strong thunderstorm 13
miles north of Benson. This storm was nearly stationary.

HAZARD...Winds in excess of 40 mph.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects.

This storm will remain over mainly remote areas of eastern Pima and
northwestern Cochise Counties.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 3205 11047 3222 11046 3227 11024 3206 11019
TIME...MOT...LOC 2117Z 280DEG 2KT 3215 11037

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...40 MPH

AH

Special Weather Statement
National Weather Service Tucson AZ
249 PM MST Thu Aug 26 2021

AZZ504-506-507-514-262230-
Santa Catalina and Rincon Mountains including Mount
Lemmon/Summerhaven-Upper San Pedro River Valley including Sierra
Vista/Benson-Southeast Pinal County including
Kearny/Mammoth/Oracle-Tucson Metro Area including Tucson/Green
Valley/Marana/Vail-
249 PM MST Thu Aug 26 2021

...A strong thunderstorm will impact portions of northeastern Pima
and southern Pinal Counties through 330 PM MST...

At 248 PM MST, Doppler radar was tracking a strong thunderstorm near
Catalina, moving northeast at 10 mph.

HAZARD...Wind gusts up to 50 mph and pea size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
Catalina, Oro Valley, Oracle, Saddlebrooke, Mount Lemmon/Summerhaven,
Catalina State Park, Catalina Foothills, Campo Bonito and Biosphere
2.

This includes Route 77 between mile markers 82 and 87, and between
mile markers 100 and 101.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 3231 11086 3247 11097 3263 11080 3247 11048
TIME...MOT...LOC 2148Z 229DEG 7KT 3246 11084

MAX HAIL SIZE...0.25 IN
MAX WIND GUST...50 MPH

Meyer