993
FXUS65 KTWC 242129
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
229 PM MST Tue Sep 24 2024

.SYNOPSIS...Dry and warmer. High pressure will push temperatures
back to well above normal levels this week and through the weekend
with the hottest days expected to be Friday and Saturday. An
Excessive Heat Warning is in effect both days from Tucson
westward.

&&

.DISCUSSION...An omega blocking pattern has set up over the
western CONUS characterized by a closed low off the coast of
California, ridge from the Pacific Northwest to the Southwest, and
a trough over the Midwest. Unfortunately this general pattern
will be in place for at least the next 7 days, which will lead to
it feeling like summer again. Current temperatures are 2-4 degrees
warmer than this time yesterday and will top out 6-8 degrees
above normal. The warmup continues into the weekend with
temperatures reaching their peak Friday and Saturday when highs
will be 10-15 degrees above normal. Many locations will see record
to above record highs over the next several days. The Tucson
airport could see its latest occurrence of 105 degrees with the
current record being Sep 22 (1989). Tomorrow chances of 105 or
greater are around 20 percent at the airport and increase to 60
percent by Saturday. Probabilities are even higher in Marana and
western Pima County. An easterly gradient will also set up through
the weekend, which could also elevate overnight temperatures
thanks to downslope warming. These temperatures are also supported
by 850mb-700mb thicknesses. HeatRisk values are in the major
category for the majority of the area from Tucson westward.
Because of this and with temperatures being at or above record
levels an Excessive Heat Warning has been issued for Friday and
Saturday from Tucson westward. After Saturday temperatures
decrease just enough to be out of the major category for most of
the area, but with the ridge still in place temperatures will
still be well above normal.

&&

.AVIATION... Valid through 26/00Z.
Generally SKC-FEW clouds 9k-12k feet through the forecast period.
Surface winds east to southeasterly and under 12 kts through 25/15Z,
then increasing to 12 to 17 kts. Aviation discussion not updated
for TAF amendments.

&&

.FIRE WEATHER...Dry conditions with a warming trend this week.
Temperatures will be 6 to 12 degrees above normal through
Thursday, peaking at 10 to 15 degrees above normal Friday and
Saturday. 20-foot winds will generally be less than 15 mph with an
easterly component through the weekend. Wednesday will see breezy
southeast winds east of Tucson. Min relative humidities will be
in the teens for the lower elevations and the middle 20s for the
higher elevations.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
Excessive Heat Warning from 10 AM Friday to 7 PM MST Saturday
for AZZ501-502-504-505.

&&

$$

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