Area Forecast Discussion
Issued by NWS Tucson, AZ
FXUS65 KTWC 300350
Area Forecast Discussion
National Weather Service Tucson AZ
850 PM MST Sat Apr 29 2017
.SYNOPSIS...Cooler temperatures will occur tonight with a freeze
expected in some colder eastern valleys. High pressure will bring
dry conditions and a strong warming trend during the upcoming week.
.DISCUSSION...IR satellite imagery and surface observations depicted
scattered to broken mid-level clouds mainly across the Upper Gila
River Valley and in the vicinity of Safford at this time. Otherwise,
clear skies with west to northwest surface winds less than 10 mph
prevailed. Clouds will continue to decrease during the next couple
of hours or so, and clear skies with light winds will be the rule
the rest of tonight.
The combination of clear skies, light winds and a very dry regime
(30/00Z KTWC sounding total precip water value was only 0.19 inches)
will translate into cooler temperatures later tonight. A Freeze
Warning remains in effect from 1 AM to 7 AM MST Sunday for lower
elevations east to south of Tucson. Sunny skies and warmer
temperatures will then occur Sunday.
Please refer to the additional sections in this product for further
.AVIATION...Valid through 01/06Z.
A few clouds around 10k ft AGL near the New Mexico border until
around 06Z Sunday otherwise clear skies. Surface wind variable in
direction less than 10 kts into Sunday morning, then surface wind
Sunday afternoon and evening wly/nwly 10-20 kts with gusts mainly
near 25 kts. Aviation discussion not updated for TAF amendments.
.FIRE WEATHER...Dry conditions will prevail into next Saturday.
Expect markedly less wind as well through Wednesday, although
afternoon gusts will occur due to daytime heating. A somewhat tight
surface pressure gradient Thursday into Friday should produce
elevated east to southeast winds. Daytime minimum relative humidity
will be in the single digits at lower elevations and the teens in
.PREV DISCUSSION /205 PM MST/...Coolest night in 3 or 4 weeks
tonight with a patchy late season freeze in colder eastern and
southern valleys. Freeze warning in effect Sunday morning for areas
east and south of Tucson. High pressure takes control next week as
the strong ridge near the west coast builds inland and pushes our
temperatures quickly back to around 7-12 degrees above average later
in the new week. We could see the first 100 of the year at TIA by
Friday, but right now the best bet is upper 90s.
Freeze Warning from 1 AM to 7 AM MST Sunday for AZZ503-507>509.
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