Area Forecast Discussion
Issued by NWS Tucson, AZ
FXUS65 KTWC 230408
Area Forecast Discussion
National Weather Service Tucson AZ
908 PM MST SUN MAY 22 2016
.SYNOPSIS...Dry conditions with below average daytime temperatures
and gusty afternoon winds will prevail most of the week. Expect
windy conditions across much of the area Wednesday as a low pressure
system approaches from the west.
.DISCUSSION...Water vapor imagery and 23/00Z upper-air plots show a
sprawling low pressure system that covers much of the northwestern
quadrant of the nation, with numerous disturbances rotating around
the low. Meanwhile, a high pressure ridge extends from the southern
plains northeastward into the Upper Midwest/Great Lakes region.
Arizona lies between these two systems, which resulted in a
continuation of breezy to locally windy conditions earlier this
afternoon and early evening. The latest surface observations
indicate that the winds have diminished considerably since sunset
with most stations reporting winds 12 mph or less. The exception
would be Safford where northwest winds remain somewhat elevated, but
will also continue to decrease throughout the evening hours.
As of 04Z (9 PM MST), temperatures ranged from the upper 60s to the
upper 70s, with the Tucson Intl Airport reporting a temp of 77 degs
after reaching an afternoon high of 90 degs, which was 4 degs below
normal for this date. These current temperature readings are right
on track with the inherited overnight low temperature forecasts, so
no changes are planned but will monitor.
See the previous discussion below for details beyond tonight.
.AVIATION...Valid thru 24/06Z.
Clear skies to scattered cirrus clouds above 25K ft AGL will prevail
thru 23/12Z, especially south-to-southeast of KTUS, with clear skies
expected all day Monday. Surface wind generally less than 10 kts
between 23/05Z and 23/15Z. Increasing surface wind aft 23/15Z, with
sly/swly surface wind at 14-22 kts and gusts to near 30 kts aft
23/19Z. Aviation discussion not updated for TAF ammendments.
.FIRE WEATHER...Dry conditions will prevail through next Saturday.
Daytime minimum relative humidity will generally range from the
upper single digits to mid teens with fair overnight recoveries.
Expect gusty south to southwest winds during the afternoon and early
evening hours. The best chance for widespread critical fire weather
conditions to occur is Wednesday afternoon for locales from Tucson
southward and southeastward to the International and New Mexico
borders. Critical fire weather conditions may again occur Thursday
afternoon across about the eastern half of Cochise county. Field
crews are encouraged to monitor subsequent forecasts for the
potential issuance of Fire Weather Watches and/or Red Flag Warnings
during the next few days.
.PREV DISCUSSION...A large scale mean trough position extending from
around the Pacific Northwest through central and northern portions
of the Great Basin will serve to keep our temperatures a few degrees
below average for late May, while also helping to keep things breezy
around the area most of the week. An impulse from British Columbia
will deepen the trough down the coast and immediately upstream of
Arizona Tuesday and Wednesday. This will create stronger winds on
Wednesday; probably strong enough for fire weather and blowing dust
concerns Wednesday afternoon.
A weak flow at the base of the filling residual trough will continue
to keep temperatures from jumping too much. However, modest height
and lower layer thickness increases will push temperatures back up a
few degrees to near typical late May averages next weekend.
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