Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 220345

Area Forecast Discussion
National Weather Service Tucson AZ
845 PM MST Tue Mar 21 2017

.SYNOPSIS...Remaining dry with unseasonably warm daytime
temperatures through tomorrow. A storm system will then bring a
chance of showers Wednesday night into Thursday. This system will
also bring gusty winds Wednesday afternoon and Wednesday night
followed by much cooler temperatures Thursday. Dry conditions with
warmer temperatures will prevail across much of the area Friday
into early next week.


.DISCUSSION...Another warm day across southeast Arizona today, with
a couple of record high temperatures being broken/tied. The record
high for Tucson International Airport (TIA) was broken with a high
of 92 degrees today (breaking the old record of 91 set in 2016) and
a record high tied at Douglas-Bisbee Airport with a high of 87
degrees (old record set in 1997). The strong high pressure ridge
responsible for the recent string of record high temperatures was
beginning to shift east of the area with a trough developing along
the west coast. Several degrees of cooling is expected tomorrow
across southern Arizona as the ridge axis shifts east into the
southern plains.

Otherwise, high clouds are expected to move into the area late
overnight into Wednesday. Gusty winds this afternoon (from Tucson
east to the New Mexico border) have diminished, with light winds
expected for the rest of the night into early Wednesday morning.
However, expect breezy to locally windy conditions from late
Wednesday morning, persisting through Wednesday evening. Overall,
the forecast package looks to be in good shape. No updates tonight.
For more information on the latter periods of the forecast, please
refer to the prev discussion section below.


.AVIATION...Valid through 23/00Z.
SKC conditions will become SCT-BKN clouds above 20k ft AGL aft
22/12Z. Surface wind less than 10 kts thru 22/16Z, then increasing
surface wind. Aft 22/18z, SLY/SWLY surface wind at 13-18 kts and
gusts to 25-30 kts, with the strongest wind south/southeast of KTUS
in the vicinity of KOLS, KDUG and KALK. Aviation discussion not
updated for TAF amendments.


.FIRE WEATHER...Expect dry conditions into Wednesday. A Pacific
storm system will then bring a chance of showers Wednesday night
followed by a chance of showers mainly northeast of Tucson
Thursday. A few snow showers may occur across the White Mountains
northeast of Safford Thursday night. Dry conditions will then
prevail Friday into Sunday. There is a slight chance of showers
across the White Mountains next Monday.

The Pacific storm system will also bring gusty mainly southwest
winds Wednesday afternoon into Wednesday night. The combination of
strong and gusty southwest winds and low relative humidity may
create critical fire weather conditions Wednesday afternoon across
the southern one-third of Fire Zone 152. At this point however, it
looks borderline with limited coverage and duration, so a Red Flag
Warning has not yet been issued. This will be monitored closely.

There will be some gusty west to northwest winds Thursday, then less
wind Friday into Saturday. Some gusty afternoon west winds are
forecast to return Sunday and next Monday.


.PREV DISCUSSION...We`ll see increasing patches of high cloud
tonight as our southwesterly flow increases ahead of the strong
Eastern Pacific trough. Temperatures today similar to yesterday.

As far as the upcoming system we`ve been monitoring, it`s becoming
increasingly clear that the majority of our precip chances this far
south will be directly associated with the frontal passage
(Wednesday night into Thursday morning). A bit of residual moisture
and instability behind the front Thursday afternoon, mainly east of
Tucson by then. Nothing to write home about with any totals under
1/4 of an inch in valleys. 2 or 3 inches of snow possible in the
White Mountain areas of northern Graham and Greenlee counties.

Surface winds will get busy Wednesday afternoon and Wednesday
evening, but not quite strong enough for an advisory (other than a
few wind prone locations in southern Cochise county). Strong enough
for some Fire Weather concerns as outlined below. Temperatures still
on the warm side ahead of the front Wednesday, but cool air will
drop temperatures to below average Thursday; down around 25-30
degrees from recent record values.

A shortwave ridge to end the week with temperatures jumping back
above average, but well short of what we`ve been seeing. The next
system this weekend will be a more traditional transition season
system, with wind the main concern and enough cool air to push
temperatures back down a few degrees.





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