Forecast Discussion

Forecast Discussion for TWC NWS Office
072
FXUS65 KTWC 122141
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
241 PM 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 late Thursday into
Friday.

&&

.DISCUSSION...

Upper level analysis features a low off the southern California and
Baja coast, while a downstream ridge sits over Arizona. While the
upper low will eject over the next couple days, the placement of the
ridge axis will remain over southern Arizona long enough to persist
excessive heat through Thursday. The high temperature on Thursday
should approach 110 in Tucson, with MOS guidance ranging from 108 to
110 and the NBM providing a 20% chance of meeting the threshold.

As the upper low approaches Thursday, a southerly push of modest mid-
level moisture should at least create some cloud build-ups during
the day. Measurable precipitation looks very unlikely, though a few
areas receiving a few sprinkles or even an isolated dry
thunderstorm can`t be ruled out. The low will fully eject on
Friday, which should create an uptick in winds with a tightened
pressure gradient. That said, the somewhat early timing of the
wave passage along it becoming more open in nature leads to some
uncertainty on the extent of the increased winds, and subsequently
the level of fire danger Friday afternoon. At this time MOS
guidance has winds approaching to around critical levels, with the
NBM just a bit lower. With dry conditions still expected to be in
place, the Fire Weather Watch looks to be in good standing for
now.

While temperatures should nudge down a few degrees under the passing
low on Friday, broad ridging is expected to redevelop again this
weekend which will bring temperatures back up around 6-8 degrees
above normal. Heat Risk will increase, but potentially not as much
as before as climatological temperatures are rising as well.

Going into next week, western CONUS troughing will lead to southwest
flow over southern Arizona, and an initially dry forecast. There
continue to be signs however of the upper high shifting into the
area around the end of next week, which may open the door for some
better mid-level moisture to arrive.

&&

.AVIATION...

Generally SKC then FEW-SCT clouds around 20k feet AGL after 02Z.
Northwest breeze gusting to around 15 kts decreases to 5 to 10 kts
after 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. Winds may increase a bit on Friday, especially east of
Tucson-Nogales and closer to the Arizona/New Mexico border. A Fire
Weather Watch remains in effect Friday for Fire Weather Zone 152
where winds of 15 to 25 mph and gusts up to 35-40 mph are possible.

&&

.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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NWS TWC Office Area Forecast Discussion