643
FXUS65 KTWC 012243
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
343 PM MST Sat Jun 1 2024

.SYNOPSIS...High temperatures will remain above normal over the
next seven days, with Thursday expected to be the hottest day.
Expect typical afternoon and early evening breeziness due to strong
solar heating.

&&

.DISCUSSION...It is empirically factual that the month of June
across Southeast Arizona is synonymous with the word hot, and the
forecast over the next seven days sure doesn`t do anything to
change that line of thinking.

Broad ridge of high pressure over northern Mexico this afternoon
with a weak dry trough of low pressure moving through the northern
Great Basin. The southern periphery of this system will track
through our neck of the woods Sunday with another weak impulse
moving through the area Monday. You know its June when you explain that
this feature will be `helpful` in keeping temperatures in the
Tucson Metro Area down around the century mark the next few days.
Otherwise, the main impact of these features will be a slight
uptick in breeziness Sunday and Monday afternoons southeast of
Tucson, especially near the Arizona/New Mexico border. Given how
dry we are, this will result in brief periods of near critical
fire weather conditions but should not be long enough or
widespread enough to warrant any fire weather headlines.

As we move into the middle of next week, we see a more amplified
longwave ridge develop across the western states with a closed low
getting trapped underneath it off the spur of the Baja. There are
some differences between the ECMWF and GEFS with regards to the
strength and overall trajectory of this feature the second half of
this week going into next weekend. The ECMWF mean is stronger
with the low, which in turn amplifies the ridge over Southeast
Arizona more so than the GEFS. Therefore, the 850-700 mb
thickness values are a bit higher with the ECMWF, but both
slightly excees 1690m Thursday afternoon...which according to our
local regression equation equates to a forecast high of 107F in
Tucson. This aligns with the NBM, with the NBM probabilities of
meeting or exceeding 105 degrees at KTUS at 59%, and 107F at 34%.
After consultation with the surrounding offices, we may need to
eventually hoist an excessive heat watch for Southeast Arizona but
have decided to hold off for another forecast cycle or so to see
if the upper low wobbles closer to Arizona cooling the forecast a
few degrees. At this time, my hunch is that we will eventually
need excessive heat products Thursday and potentially Friday. In
any event, it will be both icky and oocky (otherwise known as
meteorologically impactful) the second half of next week so we
will make a concerted effort to push heat-related safety
messaging out to the public the next several days.

Otherwise, marginal mid-level moisture will be pulled up into
Southeast Arizona as early as Thursday but more so on Friday/
Saturday. The lower levels will remain dry, so the most likely
scenario with this moisture will be a slight chance of an elevated
dry thunderstorm Friday afternoon and evening, and again Saturday
as the upper low eventually ejects NE. These type of storms are
known to produce gusty and erratic outflow winds near the
evaporating downdrafts.

&&

.AVIATION...Valid through 03/00Z.
Clear skies/SKC conditions with a FEW clouds AOA 25k ft AGL thru
the forecast period. SWLY SFC wind at 10-15 kts with gusts to
18-25 kts into the early evening, then less than 10 kts and
variable in direction overnight. Winds Sunday will be SWLY 13-18
kts with gusts to 30 kts in the afternoon. Aviation discussion not
updated for TAF amendments

&&

.FIRE WEATHER...Dry conditions and high temperatures 2-5 degrees
above normal will continue through next Wednesday, becoming 5 to 8
degrees above normal the second half of next week. Expect min RH
values of 3-8 percent in the lower elevations and 8-15 percent in
the mountains through the middle of next week, along with poor
overnight recoveries between 20-35 percent in most locations. 20-
foot winds will follow typical diurnal patterns through Wednesday
of next week, with afternoon/early evening gustiness due to strong
surface heating. Sustained 20-foot wind speeds will generally be
15 mph or less, except for the potential for some elevated winds
at 15-20 mph and gusts to around 30 mph Sunday and Monday
afternoon/early evening southeast of Tucson. There will be a
slight chance of dry thunderstorms capable of producing gusty and
erratic outflow winds near evaporating downdrafts possibly as
early as Thursday, but more likely impacting the area Friday and
Saturday.

&&

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

&&

$$

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