Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 200916

Area Forecast Discussion
National Weather Service Tucson AZ
216 AM MST THU OCT 20 2016

.SYNOPSIS...Dry conditions with above normal daytime temperatures
will continue through Saturday. Gusty east to southeast winds will
also prevail today into Friday morning. Increasing moisture will
then bring a slight chance of rain to much of the area early next


.DISCUSSION...Water vapor imagery and 20/00Z upper-air plots show a
ridge over the eastern Pacific waters, with the ridge axis extending
into northern Mexico. Meanwhile, a back door front just to our east
over west Texas and northern Mexico will result in a tightening
pressure gradient across southeast Arizona today. As a result,
expect east to southeast winds to begin to increase significantly by
around sunrise this morning, then peaking during the late morning
and early afternoon hours with speeds in the breezy to locally windy
range. The gradient is expected to remain fairly tight throughout
the evening and overnight hours, so not expecting the typical
slackening of winds during the night time hours. Winds will continue
breezy through around midday Friday before the gradient finally
relaxes, with a return to light east to southeast winds Friday

By early Friday the eastern Pacific ridge will have moved nearly
overhead, resulting in slightly warmer temperatures through Saturday
as the ridge moves to a position over the southern plains.

With the ridge well to our east and an approaching trough from the
west this weekend, we will be under southwest flow aloft, which will
contribute to pulling moisture northward. That said, models show
this increase in moisture and the subsequent increase in the
potential for showers. Showers should begin Sunday and mainly along
the border with Mexico. The best threat for showers will then occur
Monday through Tuesday (albeit small), with slight chances for the
deserts/valleys and chance type POPs for the mountains.

By late Tuesday into Wednesday the moisture will have shifted to the
east with ridging once again building to our south for a return to
dry weather.

For Tucson, high temperatures will range from 9 to 12 degs above
normal today through Sunday and 4 to 7 degs above normal thereafter.
Lows will be around 10 degs above normal Friday through Tuesday
mornings, then 5 to 7 degs above normal for Wednesday.


.AVIATION...Valid through 21/12Z.
Generally SKC thru the period, with perhaps a FEW clouds above 20k
ft AGL. Light and variable SFC wind becoming ELY/SELY at 12-15 kts
around daybreak, increasing to 15-20 kts with gusts of 25-30 kts
late this morning into this afternoon. The strongest speeds are
expected near KTUS and KSAD. Speeds will diminish some this evening,
but continue at 10-15 kts tonight into early Friday morning.
Aviation discussion not updated for TAF amendments.


.FIRE WEATHER...Above normal temperatures will prevail into early
next week. Expect dry conditions through Saturday, with a slight
chance of showers developing near the International border on
Sunday. Slight shower chances will then extend area-wide Monday into
Tuesday, with dry conditions returning next Wednesday. 20-ft winds
will increase out of the east and southeast around daybreak this
morning, with speeds of 15 to 20 mph and gusts to 30 mph this
afternoon. A few very localized spots near the Tucson area may
experience brief red flag conditions this afternoon. Elevated east
winds will continue tonight into Friday, though speeds will decrease
throughout the day. Normal diurnal wind trends will return this
weekend into the first part of next week.






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