Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 271011

Area Forecast Discussion
National Weather Service Tucson AZ
310 AM MST Thu Apr 27 2017

.SYNOPSIS...Another system north of our area will bring increasing
winds this afternoon followed by a return of strong and gusty winds
Friday into Saturday. A few showers or thunderstorms are possible
northeast of Tucson on Friday. Cooler on Saturday followed by dry
conditions with a warming trend next week.


.DISCUSSION...After a day of less wind on Wednesday, they will start
to crank up today, becoming rather strong on Friday and remaining
gusty on Saturday. Fire weather concerns for the next 3 days are
addressed below in the fire weather section. Some areas of blowing
dust possible today with better chance of seeing areas of blowing
dust as wind speeds will be approaching advisory criteria.

Today`s winds associated with short wave moving across WY/UT into CO
which tightens up the pressure gradient. Further tightening of the
gradient will occur on Friday as a follow-up system, currently in
the Gulf of Alaska this morning, dives into the Great Basin with a
cut-off low developing near the 4-corners late Friday afternoon into
Friday evening. This system will also bring an increase in moisture
with a chance of showers or thunderstorms for mainly the White
mountains at this time. Can`t rule out a stray shower getting close
to the Safford area late Friday afternoon into Friday night.

Warmer today with highs running 2-6 degrees above late April
normals. Cooler Friday with highs similar to what occurred on

Closed low moving across New Mexico on Saturday with tight pressure
gradient remaining over the area. Fire weather concerns are
addressed below. Much cooler on Saturday with highs about 10 degrees
below normal. Enjoy it. Just a hint for what may come by the end of
next week. With colder air mass over the area overnight lows
Saturday night into Sunday morning could get quite chilly especially
for the normally colder sheltered areas east and south of Tucson. A
few hours of freezing temperatures not out of the question.

Dry NW flow aloft Sunday thru Tuesday results in a warming trend
area wide. Upper ridge amplifying up the west coast on Wednesday
will move east over the state next Thursday and east of the state
next Friday. Although outside of this forecast package it is of
interest as both the GFS and ECMWF forecast low-level thickness
values suggest Tucson will make another run at the first triple
digit high of 2017 on Cinco de Mayo.


.AVIATION...Valid through 28/12Z.
SCT-BKN clouds above 20k ft AGL. SFC wind light and variable at less
than 10 kts this morning, then increasing this afternoon to 15-20
kts with gusts to 30 kts. The strongest speeds will be east of KTUS.
Looking into Friday afternoon stronger winds will be impacting all
terminal sites. Aviation discussion not updated for TAF amendments.


.FIRE WEATHER...Strong and gusty winds will continue to be a concern
the next several days. Today, the wind will pick up again in speed
during the afternoon. Latest models were still showing Red Flag
conditions across much of zone 152 and parts of southeast zone 151.
This includes the higher elevations of Whetstone Mountains near the
Sawmill wildfire.

Even stronger winds can be anticipated Friday, but models continued
to show an increase in relative humidity values. However, given the
very dry fuels went ahead and upgraded Fire Weather Watch to Red
Flag Warning. The wind will remain elevated in speed Saturday across
eastern sections on the back side of an exiting system to the north.
Humidity values will also lower on Saturday, so critical fire
weather conditions will once again be a concern. For now, will focus
on today and Friday with the expectation of a watch or warning being
posted for Saturday as the weekend draws closer. The wind settles
down next week, but very dry conditions will remain in place.


 Red Flag Warning from noon today to 7 PM MST this evening for

 Red Flag Warning from 10 AM to 8 PM MST Friday for AZZ150>152.



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