Area Forecast Discussion
Issued by NWS Tucson, AZ
FXUS65 KTWC 241701
Area Forecast Discussion
National Weather Service Tucson AZ
1000 AM MST SUN JUL 24 2016
.SYNOPSIS...Adequate moisture will provide scattered mainly
afternoon and evening thunderstorms this week. Daytime temperatures
will generally trend a few degrees above normal.
.DISCUSSION...The focus for showers and thunderstorms to occur into
this evening will likely be the White Mountains as well as south-to
southeast of Tucson according to the 24/12Z Univ. of AZ WRF-NAM,
24/09Z SREF and the 24/12Z NAM12. Ample moisture exists across
southeast Arizona this morning, with 24/12Z KTWC sounding total
precip water value of 1.51 inches. Storm motions should be quite
slow, given the surface-3 km mean wind around 4 kts.
The official forecast will continue with scattered showers/tstms
generally from Tucson eastward/southward into this evening. A slight
chance of showers/tstms exists area-wide late tonight. Will monitor
the potential influence due to an approaching inverted trough from
the southeast for late tonight into Monday.
There are no updates merited at this time. Please refer to the
additional sections for further detail.
.AVIATION...VALID THRU 25/18Z.
Scattered -TSRA/-SHRA into this evening mainly across the White
Mountains northeast of KSAD, and south-to-southeast of KTUS. Will
likely include VCTS at KOLS and VCSH at KTUS with the 18Z TAF
issuances for this afternoon and evening. A slight chance of -TSRA/
-SHRA continues late tonight into Monday morning. Brief wind gusts
to around 40 kts and MVFR conditions will occur with the stronger
TSRA. Otherwise, a few to occasionally broken cloud bases at 8k-12k
ft agl thru the period. Surface wind mainly less than 12 kts except
northwest 15-20 kts with gusts to 25 kts vicinity KSAD this
afternoon. Aviation discussion not updated for TAF amendments.
.FIRE WEATHER...Scattered mainly afternoon and evening showers and
thunderstorms will occur into next weekend. Outside of gusty
thunderstorm outflow winds, 20-foot winds will generally be terrain
driven and less than 15 mph. The exception will be the Gila River
Valley, where northwesterly winds around 20 mph with higher gusts
are possible this afternoon and Monday afternoon.
.PREV DISCUSSION /244 AM MST/...Latest models continued to show a
more favorable flow pattern to pull deeper moisture pooled south of
the International Border northward into the area. This pattern
change will be ongoing through the week with the upper high
initially becoming centered near the four corners region by Tuesday.
The GFS model then showed the upper high amplifying more and
shifting to a position over southern Nevada around Thursday and
Friday. Both of these locations of the upper high typically favor an
increase in daily thunderstorm activity across the state. The
increase in moisture and the subsequent cloudiness as well as
rainfall will moderate daytime temperatures a bit this week.
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