310
FXUS65 KTWC 100849
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
149 AM MST Mon Jun 10 2024

.SYNOPSIS...Seasonable temperatures today, then excessive heat
returns Tuesday through Thursday as high pressure results in very
hot temperatures. Slight cooling Friday into the weekend but
temperatures still a few degrees above normal. Dry conditions
through the forecast period.

&&

.DISCUSSION...The main forecast concern this week will once again be
excessive heat. Still one more day today of more normal heat (but
still triple digits for Tucson) before the excessive heat kicks in.

As a weak disturbance pushes away from our area, ridging aloft will
strengthen starting today but most notably for the middle of the
week as it centers itself near the AZ/NM border. As this occurs,
height and thickness values will increase resulting in dry
conditions and hotter temperatures. We`ve gone ahead and upgraded
the excessive heat products to a warning this forecast cycle for the
Tuesday through Thursday period. Tuesday is a bit borderline for
coverage of major heat risk with more widespread major heat risk
Wednesday and Thursday as temperatures peak through the area. Latest
forecast highs for Tucson Tuesday/Wednesday/Thursday are 107, 109
and 108 respectively and is in line with the deterministic NBM. 850-
700 mb thickness regression means from the GFS/ECMWF support these
values as well. 110 degrees is still not out of the question with
NBM probabilities 19% Wednesday and 15% Thursday. Expect some
afternoon gustiness each day due to strong daytime heat.

For the end of the week, the mid/upper low that will be located off
the California coast for much of the week is progged by the
ensembles to shift eastward into AZ. There is little moisture out
ahead of this system to work with, though some hints of mid level
moisture ahead of the trough mainly near the White Mountains that
could result in some cloud build-ups. This system will mostly just
help to `cool` temperatures down a few degrees as compared to
Wednesday/Thursday and result in some additional breezes.

Dry conditions will prevail under westerly flow for the weekend with
slightly above normal temperatures.


&&

.AVIATION...Valid through 11/12Z.
SKC to SCT clouds AOA 20k ft AGL areawide thru the forecast period.
SFC winds thru 10/18Z will be less than 10 kts and variable in
direction. Aft 10/18Z, WLY/NWLY SFC wind at 8-13 kts, with some
gusts to around 20 kts. SFC winds then diminish to less than 10 kts
through the end of the forecast period. Aviation discussion not
updated for TAF amendments.

&&

.FIRE WEATHER...Main story for this week is the hot temperatures and
dry conditions. High temperatures will be 1-3 degrees today, warming
to 7 to 10 degrees above normal Tuesday through Thursday, lowering
back to 2-5 degrees above normal late in the week and next weekend.
Expect min RH values of 5-9 percent in the lower elevations and 8-15
percent in the mountains this week, along with poor overnight
recoveries between 20-35 percent in most locations. 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 Monday through Thursday,
with elevated winds at 15-20 mph and gusts to around 30 mph to the
east/southeast of Tucson Friday and into the weekend. Areas of
elevated fire weather concerns east of Tucson will need to be
monitored for Friday.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
Excessive Heat Warning from 11 AM Tuesday to 8 PM MST Thursday for
AZZ501>509.

&&

$$

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