Flash Flood Warning 11, NWS Tucson, AZ

Area Forecast Discussion
National Weather Service Tucson AZ
946 AM MST Mon Jul 17 2017

.SYNOPSIS...Expect widespread showers and thunderstorms into
Tuesday. Heavy rainfall will occur with the stronger thunderstorms.
A chance of showers and thunderstorms will remain through the
weekend.

&&

.DISCUSSION...Deep moisture remains in place across the area with
precipitable water values 1.5 to 1.7 inches and surface dew points
in the mid to upper 60s. Each day we continue to fight through
convective inhibition left over from overnight activity, and each
day the flow is enough, in combination with the influence of our
persistent inverted trough, to reset the atmosphere relatively
quickly. That inverted trough extends from northern Chihuahua and
Sonora into southern Arizona this morning. Watch for initial
development in the partially clear areas well away from the
remnant MCS currently over southwest Arizona. That would be Santa
Cruz and southern Cochise county late this morning. Steering flow
will push storms and outflows toward the northwest and west, with
best guess for Metro Tucson activity in the early to mid
afternoon.

With a little less activity expected upstream in New Mexico, we
might actually have an overnight period without many storms.
Please see the previous discussion below for details beyond
tonight.

&&

.AVIATION...Valid thru 18/18Z.
Scattered -TSRA/-SHRA developing mainly south-to-southeast of
KTUS by late morning, then widespread -TSRA/-SHRA later this
afternoon into tonight. Otherwise, VFR conditions with cloud decks
generally 6k- 12k ft AGL, and surface wind variable in direction
mainly less than 12 kts. Aviation discussion not updated for TAF
amendments.

&&

.FIRE WEATHER...Widespread showers and thunderstorms will prevail
through Tuesday. Thereafter, the greatest daily coverage of
thunderstorms Wednesday into next weekend is expected to generally
occur east to south of Tucson. Enough moisture will remain for
isolated coverage of thunderstorms west of Tucson. Below normal
daytime temperatures will also dominate much of this week.

&&

.PREV DISCUSSION...Several HRRR solutions as well as the Univ of
AZ WRF-NAM and WRF- GFS were in good agreement that showers/tstms
will redevelop late this morning or by early this afternoon mainly
south-to-southeast of Tucson. A veering mid-level steering flow
more toward the east and southeast should translate into west-to-
northwest moving/propagating precip echoes into tonight. Have
noted that the high-res models keep northeastern sections
generally dry this afternoon, but showers/ tstms are depicted to
occur from near Tucson northeastward into the White Mountains this
evening. The favored area for showers/tstms late tonight appears
to be northwest of Tucson.

Per coordination with the Weather Prediction Center (WPC) and
neighboring WFO's, the Flash Flood Watch for all of southeast
Arizona remains in effect through this evening. Although ample
moisture will be available, various NWP model solutions suggest
fairly robust storm motions will occur. This may mitigate the threat
for widespread flash flooding.

At any rate, there were some model depictions from 24 hours or
longer ago that Tuesday may have been a relative "down" day
regarding coverage of showers/tstms. The 17/00Z GFS/ECMWF/CMC
suggest that Wednesday may now be the relative "down" day regarding
coverage of showers/tstms. Given the progged available moisture, the
presence of inverted upper troughs, and a more southeasterly mid-
level steering flow, forecast confidence of "down" days depicted via
the models is somewhat to considerably low at this time.

Thus, have made only very minor changes to the inherited PoPs into
next weekend. The scenario Wednesday into next Sunday continues with
isolated to scattered mainly afternon and evening showers/tstms. The
generally southeasterly mid-level flow regime and model generated
liquid rainfall amounts favors locales east-to-south of Tucson with
the greatest daily coverage, and lesser coverage of showers/tstms
west of Tucson.

Below normal daytime temperatures will prevail for much of southeast
Arizona into next weekend, with today and Tuesday forecast to be the
relatively coolest days.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch through this evening for AZZ501>515.

&&

Meyer/Francis

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Special Weather Statement
National Weather Service Tucson AZ
101 PM MST MON JUL 17 2017

AZZ508-512-172100-
Chiricahua Mountains including Chiricahua National Monument-Eastern
Cochise County Below 5000 Feet including Douglas/Willcox-
101 PM MST MON JUL 17 2017

...SIGNIFICANT WEATHER ADVISORY FOR NORTHEASTERN COCHISE COUNTY UNTIL
200 PM MST...

At 100 PM MST, Doppler radar was tracking a strong thunderstorm 7
miles west of Steins, or 25 miles west of Lordsburg, moving west at
15 mph.

Winds in excess of 45 mph and blowing dust will be possible with
this storm, followed by heavy rain. This is expected to impact areas
of I-10 east of Willcox.

Locations impacted include...
San Simon and Bowie.

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.

Areas of blowing dust may briefly reduce visibilities to near or
below 1 mile. If you encounter localized dense blowing dust, do not
drive into it if at all possible.

&&

LAT...LON 3209 10906 3217 10946 3241 10948 3237 10905
      3215 10905
TIME...MOT...LOC 2000Z 109DEG 13KT 3222 10911

Meyer

Special Weather Statement
National Weather Service Tucson AZ
104 PM MST MON JUL 17 2017

AZZ503-504-507-513-172045-
Upper San Pedro River Valley including Sierra
Vista/Benson-Dragoon/Mule/Huachuca and Santa Rita Mountains including
Bisbee/Canelo Hills/Madera Canyon-Upper Santa Cruz River and Altar
Valleys including Nogales-Tucson Metro Area including Tucson/Green
Valley/Marana/Vail-
104 PM MST MON JUL 17 2017

...SIGNIFICANT WEATHER ADVISORY FOR NORTHEASTERN SANTA CRUZ COUNTY
UNTIL 145 PM MST...

At 102 PM MST, Doppler radar was tracking a strong thunderstorm 20
miles west of Huachuca City, or 21 miles southeast of Green Valley,
moving north at 25 mph.

Wind gusts up to 50 mph will be possible with this storm.

Locations impacted include...
Sonoita and Elgin.

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 3159 11048 3150 11067 3183 11089 3188 11057
TIME...MOT...LOC 2002Z 165DEG 20KT 3171 11068

Zell