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fxus65 ktwc 162110 
afdtwc

Area forecast discussion
National Weather Service Tucson Arizona
210 PM MST Tue Jul 16 2019

Synopsis...after another hot day across much of the area this
afternoon, isolated to scattered thunderstorms will be around into
this evening mainly east to south of Tucson. A better flow regime
will likely increase thunderstorm coverage Wednesday afternoon
into Wednesday night. Scattered mainly afternoon and evening
thunderstorms with near normal temperatures to prevail Thursday
into early next week.



&&

Discussion...another very hot day across Southeast Arizona with
an excessive heat warning in effect through 8 PM MST this evening
across parts of Southeast Arizona. Upper air plots this morning
placed upper high over the New Mexico boot with weak south to
southwest flow aloft over the area. Precipitable water values are slightly down
versus 24 hours ago with values ranging from 0.90" to 1.30" with
highest values along the international border with even higher
values across Sonora Mexico. Radar was showing widely scattered
thunderstorms over the higher terrain south and east of Tucson.
Best area for storms, per latest high resolution models, will be
across Santa Cruz and southern Cochise County, especially from the
Patagonia Mountains to the Mule Mountains, with brief heavy rain,
hail and strong gusty winds being the main concerns. Tucson may
see some weak storms move across the Metro area, thanks to
outflows from the south southeast, between 4 and 7 PM.

High resolution models suggesting a Gulf surge overnight into
Wednesday. Normally there is a one day delay for widespread
convection, but the models are suggesting that areas south of a
Sells to Tucson to Willcox line will see scattered to numerous
showers and thunderstorms tomorrow afternoon into the evening
hours where a nice 700 mb Theta-E ridge is forecast to be. Precipitable water
values are forecast to be between 1" and 1.60" with highest values
from Tucson south. So main threat with storms tomorrow will be
wet microbursts, especially south of Tucson. Could easily see very
localized rainfall rates of 1"-2" across eastern Santa Cruz and
southwest Cochise counties. Wpc has the southern portions of the
forecast area under a marginal ero, excessive rainfall outlook,
tomorrow afternoon and evening. Not as hot tomorrow thanks to the
added moisture.

Scattered mainly afternoon and evening thunderstorms with near
normal temperatures to prevail Thursday into early next week.

&&

Aviation...valid through 18/00z.
Isolated to scattered -tsra/-shra mostly east to south of ktus
continuing into the evening. Brief wind gusts to 45 kts near
stronger thunderstorms and rain. Otherwise, cloud decks mainly 8k-12k ft mean sea level. Aside
from aforementioned T-storm gusts, surface wind into this evening
and then again Wednesday afternoon swly- nwly 10-15 kts with
gusts to 20 kts. Surface wind variable in direction under 10 kts
at other times. Storm and shower chances increase tomorrow
afternoon along with increased cloud cover. Aviation discussion
not updated for taf amendments.

&&

Fire weather...excessive heat warning until 8 PM MST this evening
from Tucson west and northwest, and portions of the upper Gila
River valley including Safford. Otherwise, isolated to scattered
mainly afternoon and evening thunderstorms this afternoon mainly
east to south of Tucson. Increased moisture and a better flow
regime should enhance thunderstorm coverage Wednesday afternoon
into Wednesday night. Thereafter, scattered mainly afternoon and
evening thunderstorms Thursday into early next week. Expect brief
strong, gusty and erratic winds near thunderstorms. Otherwise,
20-foot winds will be mainly under 15 mph.

&&

Twc watches/warnings/advisories...
excessive heat warning until 8 PM MST this evening for azz501-
502-504>506-509.

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