FXUS65 KTWC 230430
Area Forecast Discussion
National Weather Service Tucson AZ
930 PM MST Fri Jun 22 2018
.SYNOPSIS...Dry conditions continuing this weekend and during the
upcoming work week. Daytime temperatures moderating a few to several
degrees this weekend before increasing again by the middle of the
.DISCUSSION...Clear skies prevail across southeast Arizona at this
time. Dew points at lower elevations valid 9 pm MST ranged from the
mid teens across the Upper Gila River Valley to the upper 30s across
western Pima County. 23/00Z KTWC sounding total precip water value
was just 0.28 inch, down 0.10 inch versus 24 hours ago. Surface
winds valid 9 pm MST east of Tucson were westerly to northwesterly
at 10-15 mph. Surface winds from Tucson westward into the western
deserts were variable in direction less than 10 mph.
IR satellite imagery and surface observations depicted scattered to
broken mid and high level clouds across Utah extending southward
into northern Arizona. Satellite trajectories as well as 23/00Z
NAM12 and GFS moisture fields suggest the bulk of these clouds will
remain north of this forecast area the rest of tonight. However,
cannot rule out a few cirriform clouds encroaching mainly upon
northern sections by daybreak Saturday.
Have noted that these model solutions were similar versus their
respective 22/12Z solutions in depicting a modest increase in
surface-700 mb layer moisture Saturday, and even more so Saturday
night into Sunday morning. Although no rainfall is expected to
occur, this moisture increase may be sufficient for a few high-based
cumulus clouds to develop Saturday before likely dissipating
Have also noted that the 23/00Z MAV/MET guidance high temps for
Saturday was generally a couple of degrees or so warmer versus the
inherited forecast. Have opted to adjust high temps Saturday upward
accordingly. Otherwise, please refer to the additional sections in
this product for further detail.
.AVIATION...Valid through 24/06Z.
Clear skies into Saturday morning, then a few clouds at 10k-15k ft
AGL may develop Saturday afternoon before dissipating Saturday
evening. Surface wind late Saturday morning into early Saturday
evening swly to nwly 8-20 kts with gusts near 30 kts. The strongest
speeds should occur northeast of KTUS and especially in vicinity of
KSAD. Surface wind variable in direction mostly less than 12 kts at
other times. Aviation discussion not updated for TAF amendments.
.FIRE WEATHER...Dry conditions at least through the middle of the
upcoming week. A few afternoon and evening thunderstorms may
encroach upon far eastern and southern sections by next Friday.
However, forecast confidence is quite low regarding this scenario.
Some gusty southwest to northwest winds will occur this weekend,
with the strongest speeds expected across the Upper Gila River
Valley including Safford. Thereafter, 20-foot winds will mainly be
less than 15 mph with occasional afternoon gusts.
.PREV DISCUSSION /207 PM MST/...Our pattern continues with the
westerlies a little too deep for more monsoon activity. High
pressure strengthening overhead today with an excessive heat warning
for many of our mid to lower valley locations and lower deserts.
Then, troughiness (a little deeper than normal for late June)
through the front range of the Rockies will help cool things down to
average values for late June by Sunday.
There should be room for the high to rebound a little further
northward early in the new week, with temps jumping up to several
degrees above average once again by Tuesday.
Keeping an eye on the easterly wave activity across central
Mexico. They`re coming across and exiting into the eastern Pacific
just south of the Gulf of CA. As the westerlies weaken and lift a
little further northward next week, it should allow that activity
to track further north as well. A few storms near eastern
mountains not out of the question later next week, but ultimately
most mid range model resolutions and ensembles argue we aren`t
done with pesky westerly flows cutting that off again.
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