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000
FXUS65 KTWC 052049
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
150 PM MST Wed May 5 2021

.SYNOPSIS...Heating up through Thursday with normal afternoon
breeziness. An approaching storm system well north of the region
will bring cooler conditions to the area along with another round
of gusty winds for the weekend into early next week.

&&

.DISCUSSION...A couple bands of high-level clouds are drifting
across southern Arizona this afternoon, as temperatures continue on
their upward trend. This is under a building upper ridge that spans
the western US. GEFS mean 500mb heights on Thursday are forecast to
be near 1.5 standard deviations above climatology, producing the
hottest day of the forecast period. NBM guidance has been bouncing
around a 10-20% chance for the first 100 degree day occuring in
Tucson.

As this feature progresses, southerly flow taps into a moisture
source over Mexico. Thunderstorms should be firing off the Sierra
Madres, but the axis of moisture appears more centered over New
Mexico. Based on HREF/HRRR, our forecast area will be on the far
western periphery of any developing showers/thunderstorms. Chances
for wetting rain appear quite low, and dry thunderstorm chances are
in the single digits along the AZ/NM border. If nothing else, expect
to see cumulus build ups over the eastern mountain peaks.

The first of two shortwave troughs pass later on Friday, helping to
scrub a few degrees off temperatures. Winds also increase as a
result of this feature and breezy conditions remain through the
weekend into early next week. The lingering trough pattern keeps
temperatures down closer to seasonal normals, which is a
theme that remains into early next week.

&&

.AVIATION...Valid through 07/00Z.
FEW-SCT clouds AOA 25k ft MSL thru this evening then SKC thereafter.
SFC wind 8-12 kts out of the W/NW today and Thursday
afternoon/evening. Overnight and into Thursday morning winds will be
E/SE less than 8 kts. Aviation discussion not updated for TAF
amendments.

&&

.FIRE WEATHER...Hot and dry conditions continue through Thursday
with terrain driven winds mainly under 15 mph. A few build-ups are
possible along the AZ/NM border Thursday in the higher terrain.
Otherwise, increased breezes return Friday and this weekend with
brief localized critical fire weather conditions possible along the
AZ/NM border and southeast Cochise County. Expect wind speeds 15 to
20 mph with higher gusts during this period. Minimum RH values will
be 5 to 15 percent through the forecast period with generally poor
overnight recoveries.

&&

.CLIMATE...Today on Twitter we will be highlighting the new
1991-2020 normals, released yesterday, for 12 locations across
southeast Arizona. A new location will be shown each hour between
6 am and 5 pm.

&&

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

&&

$$

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