Area Forecast Discussion
Issued by NWS Tucson, AZ
FXUS65 KTWC 252215
Area Forecast Discussion
National Weather Service Tucson AZ
315 PM MST MON JUL 25 2016
.SYNOPSIS...Adequate moisture will provide scattered mainly
afternoon and evening thunderstorms into this weekend. Perhaps some
decrease in coverage will occur around Thursday. Expect hotter than
normal daytime temperatures through Thursday followed by moderating
temperatures by early next week.
.DISCUSSION...A few showers/tstms were occurring across the White
Mountains, the Galiuro Mountains in southwest Graham County, and the
Catalina Mountains near Tucson at this time. Meanwhile, a
thunderstorm developed around 2 pm on the northern portion of the
Catalina Mountains, but that thunderstorm quickly dissipated.
Otherwise, visible satellite imagery depicted mostly clear skies to
partly cloudy skies across the area at this time. The bulk of the
cumuloform clouds at least seen from WFO TWC are flat, and there will
need to be additional heating to achieve more shower/tstm development
later this afternoon.
A darkening signature representing a vort max over western Chihuahua/
southern Sonora Mexico moving northwestward may be the impetus for
broader scale forcing and subsequent shower/tstm development during
the next few hours. Various mesoscale models and particularly the
25/12Z Univ. of Arizona WRF-GFS suggest that showers/tstms will
increase in coverage especially east of Tucson by 26/00Z, then
showers/tstms should favor locales mainly south of Tucson this
For this forecast issuance, have maintained scattered showers/tstms
across much of the area this evening, then a slight chance of
showers/tstms late tonight into Tuesday morning. Similar coverage of
showers/tstms should occur Tuesday afternoon/evening. Some decrease
in showers/tstms should commence Wednesday and continue Thursday,
especially west of Tucson, as the 25/12Z GFS/ECMWF/CMC depicted some
drying to occur. Thus, PoPs were lowered particularly for Thursday,
and isolated to scattered showers/tstms are now expected to occur.
Thereafter, the medium range models were similar with depicting some
increase in moisture to return starting Friday. Thus, have opted
for a continuation of scattered mainly afternoon/evening showers/
tstms especially from Tucson eastward/southward Friday into early
High temps through Thursday will generally average about 5-8 degs
or so above normal. Daytime temps will then trend closer to
seasonal normals by early next week.
.AVIATION...VALID THRU 27/00Z.
Few-sct clouds at 8-12k ft agl with isolated to scattered -SHRA/
-TSRA mainly across the White Mtns NE of KSAD, and S to SE of KTUS.
Brief wind gusts to 45 kts and MVFR conditions are possible with the
stronger TSRA. Otherwise, sfc wind generally WLY/NWLY at 8-12 kts
into this evening, becoming mainly light and terrain driven
overnight. Sfc wind mainly less than 10 kts on Tuesday with isolated
to scattered -SHRA/-TSRA. Aviation discussion not updated for TAF
.FIRE WEATHER...Isolated to scattered mainly afternoon and evening
showers and thunderstorms will occur into this weekend. Outside of
gusty thunderstorm outflow winds, 20-foot winds will generally be
westerly to northwesterly at less than 15 mph during the
afternoons, becoming light and terrain driven overnight.
Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson