Special Weather Statement, NWS Tucson, AZ

Area Forecast Discussion
National Weather Service Tucson AZ
849 AM MST Wed Jul 31 2019

.SYNOPSIS...It will be a cooler than average day today with
scattered to numerous showers and thunderstorms, some of which will
produce heavy rainfall. Thursday into the weekend there will be less
shower and thunderstorm activity with temperatures climbing above
average again by Friday.

&&

.DISCUSSION...The moisture is fully entrenched across southeast
Arizona as advertised this morning with a PWAT of 1.89 inches on the
12Z KTWC sounding which is in line with record values we see around
here. Given the wet atmosphere and sounding with a convective
temperature of 88 degrees in Tucson, it certainly won't take much to
develop shower and thunderstorms off surface based instability with
areas that see adequate sunshine. The issue is that the situation is
more muddled than that. Current visible satellite is showing pretty
good clearing across Santa Cruz and Cochise County with mostly
cloudy skies elsewhere. Meanwhile, there is an area of showers and
embedded thunderstorms across portions of the Tucson Metro area and
these may certainly put a damper on renewed development later in the
Tucson area. In the larger picture, the best dynamics/forcing is now
across central/northern Arizona. There is still a weak mid level
trough extending from the Gulf of California into west/central
Arizona with around 15 kts of southerly mid level steering flow
across much of our forecast area. Given the low convective
temperatures, in the areas that do see sunshine, surface based
development will start earlier than normal, likely in the late
morning. Localized areas of Flash Flooding are once again possible
with the most likely areas to see heavy rain with thunderstorms
being from the Tohono O'Oodham Nation/Sells area eastward. The CAMs
aren't of much help today as they are all different and don't have a
very good handle on the current initial situation. Bottom line is
the ongoing forecast of scattered to numerous showers and
thunderstorms with locally heavy rain and below normal temperatures
continues to look good.

A reduction in shower and thunderstorm activity to a more typical
regime is expected starting Thursday and into the weekend. The high
pressure will still remain in a fairly favorable position from New
Mexico into the Four Corners region with east to southeasterly flow
aloft and more typical moisture values for early August. Therefore,
expect mainly afternoon and evening isolated to scattered shower and
thunderstorm coverage mainly east of a line from about Eloy-Sells-
Sasabe. An uptick in the monsoon is looking more likely during the
early to middle portions of next week as another inverted trough
moves north and westward from Chihuahua/Sonora into Arizona.

Temperatures will be below normal today by about 5 to 8 degrees but
then moderate back up to normal levels on Thursday. Thereafter,
temperatures will continue to warm with highs a few degrees about 3
to 5 degrees above normal Friday through the weekend.

&&

.AVIATION...Valid through 01/18Z.
Isolated -SHRA/-TSRA this morning, then expect another round of
scattered to numerous SHRA/TSRA across the region during the
afternoon and evening. Wind gusts around 40 kts are possible along
with brief MVFR cigs/vsbys with any storm. Outside of TSRA winds,
expect generally westerly winds of 4-9 kts during the afternoon then
becoming light and variable again overnight. Aviation discussion not
updated for TAF amendments.

&&

.FIRE WEATHER...Scattered to numerous showers and thunderstorms
expected again today. This added moisture/storm activity will result
in below average high temperatures through Thursday, with minimum
humidities that hover in the 30s across the lower deserts. 20-foot
winds are generally from the west and under 10 mph today except near
thunderstorms where gusty outflows are expected. Conditions start
drying up Thursday with minimum humidities approaching 20 pct in
lower elevations starting Friday. 20-foot winds will remain generally
light and terrain driven through the afternoons.

&&

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

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PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE TUCSON AZ
1155 AM MST WED JUL 31 2019

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1153 AM     HEAVY RAIN       4 N HUACHUCA CITY       31.69N 110.35W
07/31/2019  M0.70 INCH       COCHISE            AZ   TRAINED SPOTTER

            TRAINED SPOTTER REPORTED 0.70 INCHES OF RAIN
            FALLING IN 12 MINUTES.

&&

MP

Special Weather Statement
National Weather Service Tucson AZ
1208 PM MST Wed Jul 31 2019

AZZ508-513-311945-
Dragoon/Mule/Huachuca and Santa Rita Mountains including
Bisbee/Canelo Hills/Madera Canyon-Eastern Cochise County Below 5000
Feet including Douglas/Willcox-
1208 PM MST Wed Jul 31 2019

...SIGNIFICANT WEATHER ADVISORY FOR SOUTH CENTRAL COCHISE COUNTY
UNTIL 1245 PM MST...

At 1208 PM MST, Doppler radar was tracking a strong thunderstorm over
Douglas, moving northeast at 10 mph.

Winds in excess of 40 mph will be possible with this storm.

Locations impacted include...
Douglas, Bisbee-Douglas Airport and Pirtleville.

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.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 3156 10983 3146 10937 3133 10944 3134 10982
TIME...MOT...LOC 1908Z 224DEG 9KT 3133 10958

GL