Special Weather Statement, NWS Tucson, AZ

Area Forecast Discussion
National Weather Service Tucson AZ
226 PM MST Fri Jul 14 2017

.SYNOPSIS...Scattered mainly afternoon and evening will occur into
next week. The stronger thunderstorms will produce locally heavy
rainfall and strong gusty winds. Daytime temperatures will be near
seasonal normals through Saturday, then below average daytime
temperatures will prevail for most locations next week.

&&

.DISCUSSION...Slow start to convection today, with scattered
activity currently ongoing along the Mogollon Rim and just a few
cells over Cochise and southern Santa Cruz counties. The KTWC
170714/18Z release indicates warming at the mid levels. With less
cloud cover, most places should reach convective temperature this
afternoon, which will still allow for isolated to scattered
showers/thunderstorms to develop late this afternoon into the
evening hours tonight. Any cells that do develop will move to the
southwest at 15-20 mph on decent mid-level northeast flow.

Overall, the upper level pattern was defined by a large high
pressure ridge over much of the western United States, with one 594
dm high center over northwest Arizona and another over the Texas
Panhandle and an inverted trough sandwiched between these two
features to our southeast over Chihuahua, Mexico. By Sunday, the
high center will consolidate to our north over Utah, as the inverted
trough continues it's slow west/northwest progression and the flow
turns more easterly. The latest guidance figures and GFS/ECMWF model
runs all indicate that the Saturday through Tuesday time frame will
be rather active, with deep moisture in place and better dynamics as
the inverted trough edges into the region. For Tucson and areas
west, precipitation chances will be highest during the late
afternoon and evening hours, while areas to the east and along the
rim will see convection fire earlier in the afternoon.

Mid to late next week, the upper high shifts to our northeast over
Colorado, with the flow becoming southeast aloft across southeast
Arizona. With no large scale features to key in on, will need to
look for more subtle sub-synoptic features to access which day may
be more of an "up" day during this time frame. The models have a
difficult time handling these situations this far out, so have gone
with a standard monsoon forecast of isolated to scattered mainly
afternoon/evening showers and thunderstorms and lesser chances
during the overnight and early morning hours Wednesday through
Friday of next week.

Daytime high temperatures will be close to seasonal normals through
Saturday, then highs are forecast to be a few degrees below normal,
through next week, especially Monday and Tuesday.

&&

.AVIATION...Valid thru 15/23Z.
Isolated to scattered -TSRA/-SHRA will occur thru Saturday with the
periods for the greatest coverage during the afternoon and evening
hours. Brief gusts near 45 kts with the strongest TSRA. Otherwise,
VFR conditions with surface wind variable in direction mainly less
than 12 kts. Aviation discussion not updated for TAF amendments.

&&

.FIRE WEATHER...Scattered mainly afternoon and evening thunderstorms
will prevail into next week. Expect brief strong, gusty and erratic
winds due to thunderstorm outflows. Otherwise, 20-foot winds will
generally be terrain driven at less than 15 mph. Occasional gusts
will occur during the afternoon hours due to daytime heating. High
temperatures will be close to seasonal normals into Saturday, then
daytime temperatures will be at least a few degrees below normal
next week.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...None.

&&

Zell

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Special Weather Statement
National Weather Service Tucson AZ
355 PM MST FRI JUL 14 2017

AZZ509>511-142330-
Upper Gila River and Aravaipa Valleys including Clifton/Safford-White
Mountains of Graham and Greenlee Counties including Hannagan
Meadow-Galiuro and Pinaleno Mountains including Mount Graham-
355 PM MST FRI JUL 14 2017

...SIGNIFICANT WEATHER ADVISORY FOR SOUTH CENTRAL GRAHAM COUNTY UNTIL
430 PM MST...

At 354 PM MST, Doppler radar was tracking a strong thunderstorm near
Safford, moving southwest at 30 mph.

Winds in excess of 40 mph and brief heavy rain will be possible with
this storm.

Locations impacted include...
Safford, Thatcher, Solomon, Swift Trail Junction and Frye Mesa Dam.

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

LAT...LON 3301 10958 3292 10944 3257 10964 3282 10992
TIME...MOT...LOC 2254Z 034DEG 24KT 3285 10962