Special Weather Statement, NWS Tucson, AZ

Area Forecast Discussion
National Weather Service Tucson AZ
225 PM MST Tue Aug 24 2021

.SYNOPSIS...High pressure will bring hotter temperatures the
second half of the week. A chance of thunderstorms today before
storm chances wane into the weekend. Conditions are expected to be
more favorable for thunderstorms early next week.

&&

.DISCUSSION...Current radar and satellite shows isolated storms
over the Sky Islands and White Mountains. Hi-res models show this
activity continuing through the afternoon into the evening mainly
to the south and east of Tucson. The main hazards with any storms
will be locally heavy rainfall and strong outflow winds. Storms
will likely die down after sunset once they lose surface heating.
Temperatures in Tucson could hit 100 degrees this afternoon, which
would be the first time since August 7.

Temperatures continue to warm tomorrow through Friday as a ridge
currently centered over eastern Oklahoma begins to build westward.
Temperatures during this time period will be just a few degrees
below record values for most of the area. Highs will peak between
105-112 degrees in Pima, Pinal, and the Gila River Valley in
Graham County. Because of this the Excessive Heat Watch has been
upgraded to a Warning and also includes the Gila River Valley as
well. Thunderstorm chances decrease Wednesday into Friday with
chances mainly in the White Mountains and along the international
border.

This weekend into early next week expect an uptick in monsoon
activity as deeper moisture moves into southern Arizona. Ensembles
bring a tropical system, currently a disturbance 200 miles
offshore of the southeast coast of Mexico, up the Baja coast this
weekend into early next week. Based on its current trajectory this
will increase our PWAT values, first in the western part of the
CWA, then across most of southeast Arizona. This would result in
isolated to scattered showers and thunderstorms over most of our
area Sunday into the beginning of the week. There is still great
uncertainty with the path of the tropical system, but an increase
in moisture does look like a good possibility. Temperatures will
also moderate down to normal or just above normal this weekend.

&&

.AVIATION...Valid through 26/00Z.
Isolated to perhaps scattered SHRA/TSRA will develop east of KTUS
and KOLS the rest of the afternoon and into the evening. KOLS may
see VCSH or VCTS briefly late afternoon or early 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...
A near to below normal monsoon pattern is expected through late this
week. Isolated to scattered storms will be possible each afternoon
primarily east and south of Tucson and over the higher elevations.
An uptick in storm activity will be possible into the weekend. Temps
will remain above normal through at least Friday with triple digit
temps 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.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
Excessive Heat Warning from 10 AM Wednesday to 8 PM MST Friday
for AZZ501-502-504>507-509.

&&

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Special Weather Statement
National Weather Service Tucson AZ
644 PM MST Tue Aug 24 2021

AZZ507-513-250230-
Upper San Pedro River Valley including Sierra
Vista/Benson-Dragoon/Mule/Huachuca and Santa Rita Mountains including
Bisbee/Canelo Hills/Madera Canyon-
644 PM MST Tue Aug 24 2021

...A strong thunderstorm will impact portions of western Cochise and
northeastern Santa Cruz Counties through 730 PM MST...

At 643 PM MST, Doppler radar was tracking a strong thunderstorm near
Elgin, or 15 miles northwest of Sierra Vista. This storm was nearly
stationary.

HAZARD...Wind gusts up to 50 mph and pea size hail, along with heavy
         rain.

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...
Huachuca City, Elgin, Fort Huachuca and Canelo.

This includes the following highways...
 Route 82 near mile marker 41.
 Route 83 between mile markers 5 and 26.
 Route 90 between mile markers 315 and 317.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

&&

LAT...LON 3141 11041 3162 11063 3173 11052 3159 11030
TIME...MOT...LOC 0143Z 217DEG 2KT 3163 11050

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

Meyer