Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 202245

Area Forecast Discussion
National Weather Service Tucson AZ
345 PM MST Mon May 20 2019

.SYNOPSIS...Isolated showers ending this evening with clearing
skies area wide. Much cooler air mass over the area will result in
chilly to cold overnight lows with the coldest overnight lows
Tuesday moring for the valleys mainly east and southeast of
Tucson. Another weak storm system brings a chance of showers and
cooler temperatures to the area on Wednesday. Expect a gradual
warming trend into the weekend with temperatures approaching


.DISCUSSION...Rainfall amounts from Tucson east so far today has
mainly been less than 0.10" with very localized amounts of 0.25".
Doppler radar was showing isolated shower activity from Tucson
east which will continue into early this evening, especially
across Graham and Greenlee counties. Peak wind gusts so far this
afternoon has been mostly in the 25 to 40 mph range with localized
gusts up to 45 mph. Finally the temperatures have been quite cool
for May with highs running 18 to 25 degrees colder than normal.

Tonight: Clearing skies will result in a chilly to cold night
across the area. With a colder air mass over the area record or
near record low temperatures are possible, especially across
Cochise county with the coldest valleys potentially seeing lows in
the upper 20s to the lower 30s. Went ahead and upgraded the Freeze
Watch to Warning in the package for the Sulphur Springs Valley
and portions of NE Santa Cruz county.

Tuesday: Zonal flow with the area between two weather systems.
Gusty afternoon winds will still be around with high temperatures
6 to 12 degrees warmer than Monday.

Wednesday: System #2 will bring another round of gusty winds, well
below normal temperatures and a slight chance of showers or
thunderstorms. Latest guidance has any shower activity will mainly
be west of Tucson. May eventually need a wind advisory for areas
east of Tucson.

Thursday thru Memorial Day: Dry with gusty afternoon winds under
southwest flow aloft with upper level trofiness remaining over the
west coast. Daytime temperatures will be warming but remaining
below normal.


.AVIATION...Valid through 22/00Z.
Skies generally SCT-BKN mainly 4-8k ft thru 22/00Z with skies
clearing this evening and remaining clear Tuesday. Isolated -SHRA/-
TSRA KTUS eastward through 21/00z. Surface winds WLY at 15-25 kts
with gusts up to 35 kts into early this evening with the strongest
winds near KDUG. Wind easing to less than 10 kts aft 21/03Z, then
aft 21/18Z becoming SWLY at 15-25 kts area-wide with gusts up to 40
kts possible near the NM border.  Aviation discussion not updated
for TAF amendments.


.FIRE WEATHER...Breezy to windy conditions will continue Tuesday as
the pressure gradient remains tight between the weather system that
pushes through the area Monday and another moving in on Wednesday.
While wind speeds and RH values will meet critical thresholds for
brief periods Tuesday afternoon, as per discussion with local fire
agencies, the overall fire danger is moderate so will not issue any
Red Flag headlines. That said, given the strong winds, and some
curing of grasses, those shorter fuels will be more susceptible to

As the next system moves in on Wednesday, the winds will remain
elevated especially across Cochise County, however the RH values
will once again increase such that most locations will be above
critical levels. Beyond that an upper low/trough will remain near
the west coast which will keep temperatures below normal but the
atmosphere will dry out with lower RH values and more typical
afternoon breezes each day through the weekend.


.CLIMATE...Record or near record low temperatures are in the
forecast Tuesday morning, mainly across Cochise County.

DATE: May 21
SIERRA VISTA             40   39/1905
TOMBSTONE                35   40/1962
WILLCOX                  32   28/1911


 Freeze Warning from 3 AM to 7 AM MST Tuesday for AZZ507>509.



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