Special Weather Statement, NWS Tucson, AZ

Area Forecast Discussion
National Weather Service Tucson AZ
230 PM MST Sat Jul 22 2017

.SYNOPSIS...Scattered to numerous afternoon and evening
thunderstorms will prevail into early next week. The greatest
daily thunderstorm coverage should occur east to south of Tucson
with reduced thunderstorm activity across the western deserts.

&&

.DISCUSSION...Activity got off to a quick start this morning with
first storm of the day popping up over the Chiricahua mountains
after 830 am which produced around 0.80" in less than an hour.
Mountain storms struggling to maintain themselves once they move
into lower elevations. With well above normal PW values in place,
between 1.60" and 1.85, heavy rain main threat this afternoon into
the evening hours, especially in the mountains. Thus went ahead and
hoisted a flash flood watch for areas east and south of Tucson.
The MCV mentioned in the morning discussion that was near Glenwood
NM in Catron county was over western Grant county in NM and drifting
south. For tonight scattered showers and thunderstorms, more
numerous east and south of Tucson. Tucson will have to rely on
outflow interactions for storms in the city.

Flow aloft becomes more E-SE later tonight as models move inverted
trof, which extended from NW NM to southern Sonora MX this morning.
Sunday has the potential to be rather gunked over for the bulk of
the day with showers around and embedded isolated thunderstorms.

High temperature forecast a challenge with MOS numbers rather cool
for July with lots of clouds around. At this time, the official
forecast high in Tucson for Sunday of 89 degrees would be the first
sub-90 high in July since 2010.

Monsoon train remains on the track next week, although there could a
slowdown day or two, while high temperatures warm back to late July
normal values.

&&

.AVIATION...Valid thru 24/00Z.
Scattered to numerous TSRA/SHRA this afternoon/evening, then
isolated to scattered -TSRA/-SHRA late tonight into early Sunday
morning. Scattered to numerous TSRA/SHRA developing again late
Sunday morning and afternoon. Otherwise, VFR conditions with cloud
decks generally 5k-10k ft AGL. Surface wind variable in direction
mainly less than 12 kts, except in the vicinity of TSRA where gusts
may exceed 45 kts. Aviation discussion not updated for TAF
amendments.

&&

.FIRE WEATHER...Scattered to numerous mainly afternoon and evening
thunderstorms will continue into Monday with locally heavy rain and
strong winds. Isolated to scattered showers and thunderstorms are
then expected Tuesday into next weekend. Temperatures will remain
below normal through Tuesday, with near normal readings the rest of
the week. 20-foot winds will remain below 15 mph with the exception
of strong outflow winds in the vicinity of thunderstorms.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
 Flash Flood Watch until 11 PM MST this evening for AZZ503-507>513.

&&

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Special Weather Statement
National Weather Service Tucson AZ
349 PM MST SAT JUL 22 2017

AZZ507-509-511-222330-
Upper Gila River and Aravaipa Valleys including Clifton/Safford-Upper
San Pedro River Valley including Sierra Vista/Benson-Galiuro and
Pinaleno Mountains including Mount Graham-
349 PM MST SAT JUL 22 2017

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHWESTERN GRAHAM COUNTY UNTIL
430 PM MST...

At 348 PM MST, Doppler radar was tracking a strong thunderstorm just
west of Mt Graham, or 29 miles west of Safford, moving southwest at
15 mph.

Dime size hail and wind gusts up to 50 mph will be possible with this
storm, along with heavy rain.

Locations impacted include...
Fort Grant and Bonita.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Heavy rainfall is also occurring with this storm, and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.

&&

LAT...LON 3278 11019 3262 10990 3243 11005 3251 11043
TIME...MOT...LOC 2248Z 038DEG 14KT 3267 11016

Meyer