325
FXUS65 KTWC 120851
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
150 AM MST Wed Jun 12 2024

.SYNOPSIS...Excessive heat continues through Thursday as
high pressure results in very hot temperatures. Slight cooling
Friday but temperatures still a few degrees above normal.
Temperatures then nudge upward again this weekend into early next
week. Generally dry conditions through the forecast period with a
slight chance of mainly dry thunderstorms in the eastern mountains
late Thursday into Friday.

&&

.DISCUSSION...The main forecast concern in the short term will
continue to be the heat. An Excessive Heat Warning remains in effect
for lower elevations through Thursday. The ridge of high pressure
aloft will be peaking in strength today through Thursday as its
located near the AZ/NM border. Tucson will be right on the cusp of
110 degrees for high temperatures both today and Thursday. NBM
probabilities are right around 20 percent for 110 or greater both
days. If Tucson hits 110 it would be a couple of weeks earlier than
the long term average of June 28th since 1895.

As a mid/upper low off the CA/northern Baja coast ejects to the east
near San Diego Thursday evening and then into AZ Friday, that will
set the stage for some increased breeziness Thursday with locally
elevated fire weather conditions. In addition, a bit of mid level
moisture is expected in the southerly flow ahead of the low, so
there will be a few more cloud build-ups Thursday with a slight
chance of a sprinkle/light shower or dry thunderstorm Thursday night
into Friday across the higher terrain of Graham and Greenlee
Counties. The gradient will tighten a bit more on Friday as the low
ejects east and opens up into an open wave. The uptick in winds
Friday for locales east of Tucson is enough to result in areas of
critical fire weather and therefore a Fire Weather Watch remains in
effect for much of southern Greenlee/SE Graham and eastern Cochise
Counties. Meanwhile, as heights/thicknesses drop slightly,
temperatures will back off a few degrees compared to today and
Thursday.

For this weekend, ensembles are showing broad ridging building back
in to our south with SE Arizona on the north side of this ridge
under westerly flow aloft. This will result in dry conditions with
temperatures nudging up again this weekend. We`ll continue to
monitor for the need of additional heat headlines but given that
we`re getting later into June when it`s climatologically a bit
hotter, it takes a bit more to see widespread major heat risk. At
this time, heat risk for the weekend is mostly in the moderate
category with a couple localized spots at the major levels.

For early to mid next week, our area will generally be in
southwesterly flow aloft between broad troughing to our north and
west and the subtropical high to our south and east. Ensembles are
showing a dry forecast for us as moisture is well to our south and
east. However, some hints that the high could shift a bit more
northward in the 8 to 10 day period which could open the door for a
bit more mid level moisture increase. One step at a time as Monsoon
2024 gets underway after the official June 15 start.

&&

.AVIATION...Valid through 14/12Z. SKC thru 13/18Z then FEW-SCT
clouds 12-16k ft AGL through the end of the forecast period. SFC
winds generally less than 12 kts this morning, then WLY/NWLY at 10-
15 kts aft 13/20Z with gusts around 20 kts. Winds then diminish to
generally less than 12 kts aft 14/03Z. Aviation discussion not
updated for TAF amendments.

&&

.FIRE WEATHER...Hot temperatures this week, with high temperatures
7-10 degrees above normal through Thursday and then 3-6 degrees
above normal Friday through the weekend. Limited mid-level moisture
will result in a slight chance of mainly dry thunderstorms in the
higher terrain northeast of Tucson late Thursday and Friday. These
storms may produce gusty and erratic winds, along with occasional
lightning. Expect min RH values of 3-9 percent in the lower
elevations and 7-15 percent in the mountains through this weekend,
along with poor overnight recoveries between 20-35 percent in most
locations. Outside of any thunderstorm outflows, 20-foot winds will
follow typical diurnal patterns, with afternoon/early evening
gustiness due to strong surface heating. Sustained 20-foot wind
speeds will generally be 15 mph or less today, increasing to around
15 mph Thursday. Thereafter, elevated winds at 15-22 mph and gusts
to around 35-40 mph along the Arizona/New Mexico border Friday. This
will result in critical fire weather conditions. Therefore, A Fire
Weather Watch is in effect Friday for Fire Weather Zone 152
(including Cochise, Graham and Greenlee counties). Afternoon breezes
continue this weekend but below critical levels.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...

Excessive Heat Warning until 8 PM MST Thursday for AZZ501>509.

Fire Weather Watch from Friday morning through Friday evening
for AZZ152.

&&

$$

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