Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 232151

Area Forecast Discussion
National Weather Service Tucson AZ
250 PM MST Fri Jun 23 2017

.SYNOPSIS...Very hot temperatures will continue this weekend.
Isolated to scattered thunderstorms will occur east of Tucson
Saturday afternoon, then scattered thunderstorms from Tucson
eastward Sunday into Tuesday. Expect less thunderstorm coverage with
temperatures lowering closer to seasonal normals late next week.


.DISCUSSION...Isolated showers developed around 130 pm MST across
the central/southern Chiricahua Mountains, or very close to that
depicted via several HRRR solutions and the 23/12Z Univ of AZ WRF-
NAM. These showers and perhaps thunderstorms will likely produce
minimal rainfall before dissipating around 5-6 pm MST or so.

Strong high pressure aloft will remain centered over southern
Arizona this weekend. Various NWP models depict a gradual westward
import of somewhat deeper moisture into the area starting Saturday
and continuing into early next week. Expect isolated to scattered
thunderstorms Saturday afternoon and evening east of Tucson.
Scattered showers and thunderstorms should then occur mainly from
Tucson eastward and southward Sunday and Monday, especially during
the afternoon and evening hours.

Thereafter, the 23/12Z GFS/ECMWF deterministic solutions depict a
gradual decrease in thunderstorm coverage to occur starting Tuesday
and continuing into next Friday. Curious to note that the GFS is now
generally more-robust with model-generated liquid precip amounts
versus the ECMWF, which had been more-robust with liquid precip
amounts versus the GFS for several model cycles. This appears to be
due to a somewhat less amplified upper trough depicted by the GFS
over the western CONUS later next week, versus the now deeper upper
trough scenario depicted via the ECMWF.

At any rate, expect isolated to scattered showers/tstms mainly east
to south of Tucson Tuesday, then isolated to scattered showers/tstms
mainly south-to-southeast of Tucson Wednesday. A slight chance of
showers/tstms Thursday is then confined mainly to higher terrain
southeast of Tucson, with dry conditions area-wide next Friday.

Some adjustments to temperatures led to earlier expirations of
Excessive Heat Warnings and Heat Advisories for locales east of
Tucson versus previous product issuances. Please refer to the
Watches/Warnings/Advisories section of this Area Forecast Discussion
for detail. Otherwise, very hot daytime temperatures to continue
this weekend, then daytime temperatures will lower closer to
seasonal normals Wednesday into next Friday.


.AVIATION...Valid thru 25/00Z.
Isolated -TSRA near mountains northeast of KDUG ending early this
evening, then isolated -TSRA east of KTUS Saturday afternoon. Brief
wind gusts to 40 kts may occur. Otherwise, VFR conditions into
Saturday afternoon. Surface wind wly/nwly 10-20 kts with gusts to 25
kts diminishing this evening and becoming less than 10 kts by
24/06Z. Surface wind Saturday afternoon swly to nwly 5-15 kts with
gusts to 20 kts. Aviation discussion not updated for TAF amendments.


.FIRE WEATHER...Isolated to scattered thunderstorms east of Tucson
Saturday afternoon and evening, then scattered thunderstorms
generally from Tucson eastward and southward Sunday into Tuesday.
Expect decreasing coverage of thunderstorms Wednesday, with isolated
to scattered thunderstorms mainly east to south of Tucson. Dry
conditions are forecast to prevail across much of the area next
Thursday and Friday.

Otherwise, gusty east to southeast winds will likely occur Saturday
night into Sunday morning. The favored locales will be the Upper
Gila River Valley including Safford, and near the Tucson metro area.
20-foot winds will then exhibit diurnal trends with speeds mainly
less than 15 mph, although some stronger afternoon gusts to occur
due to daytime heating.


Heat Advisory until 7 PM MST this evening for AZZ510-512.

Excessive Heat Warning until 7 PM MST Saturday for AZZ508.

Heat Advisory until 7 PM MST Saturday for AZZ511-513.

Excessive Heat Warning until 7 PM MST Sunday for AZZ501>507-509-515.

Heat Advisory until 7 PM MST Sunday for AZZ514.




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