Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 231012

Area Forecast Discussion
National Weather Service Tucson AZ
310 AM MST FRI SEP 23 2016

.SYNOPSIS...A strong low pressure system moving north of the area
will bring a chance of showers and/or thunderstorms, cooler
temperatures and gusty winds at times today. Mostly dry conditions
will then prevail this weekend. Moisture and a slight chance of
showers returns to the area early next week as an upper level low
moves west across Sonora Mexico.


.DISCUSSION...A few showers developed late last night into early
this across eastern Pinal and Graham counties. Water vapor imagery
this morning showed an upper level low over eastern Nevada with the
trof axis extending south into western Arizona. Latest high
resolution models indicate mainly isolated showers/storms will be
around today as the upper level trof axis pushes across the area.
Much cooler today, especially from Tucson east, where highs will run
about 4-14 degrees cooler versus yesterday. Breezes will also be
around today.

Over the weekend a piece of energy will break off the above
mentioned upper low and move south along the AZ/NM border. Over the
past several days, the models have been flip-flopping on this idea.
Now the NAM/GFS/ECMWF/Canadian all are on the same page. However
what happens when this upper low finally digs south into Sonora
Mexico and starts to retrograde to the west early next week is very
much uncertain. How much moisture does this upper low pick up from
Texas and New Mexico and does it potentially tap into eastern
Pacific tropical Have made some changes to the inherited forecast by
introducing slight chance PoPs as early as Sunday across the eastern
areas and slowly push them west early next week.


.AVIATION...Valid through 24/12Z.
Isolated -SHRA/TS with cloud decks of 6-8k ft AGL. Most activity
will be done after 24/03z. Sfc wind terrain driven this am then
become breezy at times this afternoon with strongest gusts occuring
at KDUG.


.FIRE WEATHER...Isolated showers and storms are possible through
this evening as an upper level trof moves across the state. Gusty
southwest winds of 10 to 20 mph will be around this afternoon before
subsiding this evening. Dry most of the weekend with mainly light
winds. Moisture returns to the area from the east as an upper level
low, which drops south along the Arizona/New Mexico border moves
west across Sonora Mexico. Thus early next week will see a chance of
showers and thunderstorms across the area.





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