910
FXUS65 KTWC 240842
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
143 AM 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.

&&

.DISCUSSION...Summer is back for a second round this week into the
weekend as strong ridging is going to dominate our weather.
Ensembles show this ridge building over the upcoming days between
two troughs over the eastern Pacific and Mississippi Valley. This
ridge will have only minor variations in movement for the next 7 to
10 days which means our main weather story is turning to late season
heat. Still not so bad in the short term as heights and thicknesses
are on the rise, though triple-digit heat for Tucson returns as
early as today. Not much else in the short term, though some east to
southeast breezes are expected Wednesday.

The hottest temperatures are expected to peak in our forecast area
Friday and Saturday when highs will be 10 to 15 degrees above normal
with many locales likely to see record high daily temperatures. The
forecast high of 106 for Friday and Saturday in Tucson is on the
high end of the NBM ensemble spread but is supported nicely by
thicknesses per local thickness regression study. To put those kind
of temperatures in context, the latest Tucson high temperature at or
above 105 is September 22 (1989). HeatRisk values are at borderline
high levels Friday and Saturday from Tucson westward. One important
thing to keep in mind is that HeatRisk takes into account
climatology, therefore the temperature thresholds for high HeatRisk
are considerably lower in late in September than June through
August. Given that the high HeatRisk levels are still borderline
Friday and Saturday, decided to defer on issuance of any heat
headlines. Temperatures will then back off a few degrees by early
next week, though still remaining well above normal and tacking on
more triple-digit heat days for Tucson.

&&

.AVIATION...valid through 25/12z.
Generally SKC-FEW clouds 8-12k ft AGL through the forecast period.
SFC winds will generally be less than 12 kts and becoming mainly
ELY/SELY. Aviation discussion not updated for TAF amendments.

&&

.FIRE WEATHER...Dry conditions with a warming trend this week.
Temperatures will be 4 to 10 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 the occasional
gust. Min relative humidities will be in the teens for the lower
elevations and the middle 20s for the higher elevations.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$


Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson