Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 120442

Area Forecast Discussion
National Weather Service Tucson AZ
940 PM MST Fri Aug 11 2017

.SYNOPSIS...Scattered to numerous thunderstorms will return this
weekend with heavy rain at times. A drying trend will begin Monday
and continue during the upcoming week, with only isolated
thunderstorms mainly east to south of Tucson late next week.


.DISCUSSION...Scattered thunderstorms were occurring at this time
mainly across northern Greenlee County and northeast Graham County
northeast of Safford. Other isolated thunderstorms were also ongoing
in southwest Graham/northwest Cochise Counties. Movement of these
showers and thunderstorms was toward the northeast. Otherwise, clear
skies prevailed west of Tucson with mostly clear skies to mostly
cloudy skies elsewhere.

Radar trends suggest that showers/tstms will continue during the
next several hours from just northeast of Tucson northeastward into
the White Mountains. Several HRRR solutions as well as the 12/00Z
NAM12 and GFS affirm this scenario. The official forecast was
updated for reduced PoPs versus the inherited forecast the rest of
tonight from Tucson westward. Thus, dry conditions into early
Saturday morning west of Tucson, and isolated to scattered showers/
tstms generally east of Tucson. The bulk of showers/tstms should end
by daybreak Saturday. Expect greater coverage of showers/tstms
Saturday afternoon/evening.

Please refer to the additional sections for further detail.


.AVIATION...Valid thru 13/06Z.
Scattered -TSRA/-SHRA northeast of KTUS ending around daybreak
Saturday. Scattered to numerous -TSRA/-SHRA especially KTUS vicinity
eastward Saturday afternoon and Saturday evening. Forecast
confidence is sufficiently high to warrant VCSH in the KTUS/KOLS/
KDUG TAFs with the 12/06Z issuance for Saturday afternoon and
evening. Wind gusts potentially to near 40 kts with the stronger
thunderstorms. Otherwise, surface wind variable in directions mainly
less than 12 kts. Aviation discussion not updated for TAF amendments.


.FIRE WEATHER...Scattered to numerous thunderstorms this weekend
followed by a gradual decrease in thunderstorms from west-to-east
Monday into next Friday. Isolated afternoon and evening
thunderstorms will likely be limited to locales east-to-south of
Tucson late next week. 20-foot winds will generally be terrain
driven less than 15 mph apart from thunderstorms.


.PREV DISCUSSION /219 PM MST/...Storm chances will increase this
weekend as a disturbance moves north out of Mexico. Upper level
difluence/divergence indicated with operational models indicating
heavy rain amounts south and east of Tucson.

Storm chances will linger into Monday before another westerly
intrusion of drier air works into SE AZ bringing at least a short
break in daily thunderstorms for the middle of next week, possibly
through Friday.

High temperatures will be slightly below normal in the wetter
locations this weekend, then rebound next week when it dries out.






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