402
FXUS65 KTWC 172225
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
325 PM MST Tue Sep 17 2024

.SYNOPSIS...Breezy and dry conditions with temperatures a few
degrees cooler than normal through the work week. Temperatures are
forecast to warm above normal again late this weekend.

&&

.DISCUSSION...The upper air pattern this afternoon was characterized
by a deep trough centered over the Great Salt Lake as a secondary
reinforcing trough makes its way into the Pacific Northwest. The
remaining influence of the primary trough will gradually exit the
area this afternoon and evening leaving noticeably cooler and drier
air in its wake along with continued breezy southwest winds. In
fact, high temperatures this afternoon will be around 3 to 6 degrees
below normal. Low and mid-level moisture has begun to scour out from
west to east across western and central Pima County with a tight
precipitable water gradient moving into eastern Pima County this
afternoon. Just enough moisture remains for scattered plumpy Cumulus
clouds to continue thriving to the east of the gradient across
southeast Arizona.

As remaining moisture continues to get scoured and shunted to the
south and east, precipitation chances will remain low heading into
next week. The secondary trough will approach the area Friday into
Saturday reinforcing cooler and drier conditions across the forecast
area. Morning lows will start to dip into the 50s over normally
colder eastern/southern valleys, and low to mid 60s in and
north/west of Tucson. Ensemble height anomalies return to near to
above normal Sunday onwards, leading to an above normal temperature
forecast into next week.

&&

.AVIATION...Valid through 19/00Z.
SCT-BKN clouds 6-9k feet this afternoon gradually decreasing in
coverage after sunset. Surface winds SWLY at 10 to 15 kts with gusts
to 25 kts. Winds become light and terrain driven after 18/03Z.
Tomorrow, mostly SKC conditions through the valid forecast period.
Southwest winds pick up again after 18/17Z with speeds of 8 to 12
kts with gusts to around 20 kts. Aviation discussion not updated for
TAF amendments.

&&

.FIRE WEATHER...Crossing low pressure this afternoon and evening
will continue to bring in dry air, breezy winds, and temperatures
3 to 6 degrees below normal. Breezy southwest winds will continue
this afternoon with speeds of 12 to 18 mph and localized gusts to
30 mph. Lingering moisture will keep minimum relative humidities
from falling off too quickly this afternoon, but valley locations
are forecast to fall to the 15 to 20 percent range this week and
10 to 15 percent as temperatures warm again this weekend. Winds
will be breezy each day before diminishing by the weekend.


&&

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

&&

$$

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