Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 060415

Area Forecast Discussion
National Weather Service Tucson AZ
915 PM MST Mon Dec 5 2016

.SYNOPSIS...A few rain and snow showers may occur across the White
Mountains Tuesday night into Wednesday. Otherwise, dry conditions
will prevail into early next week. Some minor cooling will occur
Wednesday, then above normal daytime temperatures will return Friday
into next Monday.


.DISCUSSION...Increasing high clouds tonight with clouds thickening
tomorrow as a disturbance moves through the four corners region.
Still calling for a few rain and snow showers mainly in the White
Mountains Tuesday night and Wednesday. Otherwise, dry elsewhere.
Please refer to the additional sections for more details.


.AVIATION...Valid through 07/06Z.
SCT-BKN cirrus AOA 20k ft agl through Tuesday. SFC wind less than 10
kts overnight with SW winds around 12-15 kts developing during the
day on Tuesday. Aviation discussion not updated for TAF amendments.


.FIRE WEATHER...There is a slight chance of rain and snow showers
across the White Mountains late Tuesday night and Wednesday.
Otherwise, dry conditions will continue into early next week. 20-ft
winds will be gusty around 15 to 20 mph from the southwest on
Tuesday, with winds becoming easterly or southeasterly on Thursday
and Friday. 20-foot winds will mainly follow terrain at less than 15
mph at other times.


.PREV DISCUSSION...The upper level pattern into early next week will
generally be characterized with a trough over Canada extending south
into the central/eastern CONUS. Meanwhile, a ridge will prevail near
the West Coast. A shortwave trough embedded within the southwestern
periphery of the upper trough is progged to move southeastward
across the Four Corners region Tuesday night, then eastward into the
central CONUS plains Wednesday.

There continue to be differences amongst the NAM/GFS/ECMWF regarding
precip potential for Tue night/Wed. The 05/12Z NAM continues similar
versus previous NAM solutions, and depicts a few hundredths of an
inch of liquid amounts mostly across western Pima County as early as
Tue morning and continuing into Wednesday. Meanwhile, the 05/12Z GFS
continues to depict a few hundredths of an inch across the White
Mountains Wednesday.

However, this GFS solution now depicts measurable amounts much
further south, or near the International border adjacent Santa
Cruz/Cochise Counties. For this forecast package and per coord with
WFO EPZ, this solution is discounted. The 05/12Z ECMWF has trended
drier versus previous ECMWF solutions, and now depicts a few
hundredths of an inch liquid amounts to remain north of this
forecast area across southeast Arizona.

At any rate, the official forecast continues with a slight chance of
rain/snow showers across the White Mountains Tuesday night and
Wednesday. Otherwise, the aforementioned upper level pattern
suggests occasional periods of cirriform clouds to move across the

Expect no significant change in daytime temps Tuesday versus this
afternoon. Cooler temps will occur Wednesday as the shortwave trough
passes northeast of the area. A warming trend will then prevail Thur-
Fri, then only very minor daytime temp changes are forecast to occur
this weekend and early next week. High temps Fri-Mon will average
about 2-5 degs or so above normal depending upon location.






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