Special Weather Statement, NWS Tucson, AZ

Area Forecast Discussion
National Weather Service Tucson AZ
253 PM MST Sun Jul 18 2021

.SYNOPSIS...Thunderstorms are expected through this evening, mainly
east and south of Tucson. Thereafter expect daily chances of showers
and thunderstorms through the work week. High temperatures will
remain below normal into the foreseeable future.

&&

.DISCUSSION...Convection east of Tucson developing a few hours
earlier than most CAM solutions suggested and speaks to the level of
instability we have. The storms are moving to the NW, however fairly
slowly and the few we have had have produce in excess of two inches
of rain in 1 to 1.5 hours. A few of them have shown a tendency to
redevelop in the same area as well.

The saturated soils were very evident after this morning which
resulted in flooding in Santa Cruz county with only one inch of rain.
We also had flow in the Pima, Finger Rock and Esperero canyons this
morning from 1/2 to 1 inches of rain, so we are definitely primed in
that respect.

For this afternoon and evening, all the CAM solutions show
significant storm development east and south of Tucson including
areas that have received recent heavy rains. Looking at the HREF,
it is indicating fairly high probabilities of local areas of greater
than an inch (in 3hr) this evening (5-8 pm) focused over eastern
Pima, Santa Cruz and Cochise county, peaking at 70% eastern Cochise.
There is even a 10% chance of greater than 3 inches in much of that
area. Then for the 03Z-06Z period (8-11pm) the focus shifts to
Cochise county with >50% of an inch and ~10% greater than 3 inches
and has an MCS look to it. Given that and the saturated conditions
we opted to issue a Flash Flood Watch through Midnight tonight east
and south of Tucson, including Mt Lemmon for the Bighorn fire scar.
Now we will have to see how this plays out, but the potential is
certainly there.

Monday through the work week the upper level high remains near or
north of the 4-corners area, a favorable location for activity with
deep easterly flow and plenty of moisture. Therefore there will be
daily rounds of convection through the week, primarily focused on the
afternoon and evening hours and varying from day to day. That said,
as we saw this morning convection will be possible at anytime day or
night depending on smaller forcing mechanisms. PWs remain as high as
they have been so showers and thunderstorms will continue to be
efficient rain producers and with the moist soil conditions, local
flooding will continue to be a concern.

Late in the week into the weekend there is some indication that
there could be a trough over the area which would serve as a focus
for convection if it becomes reality. Too soon to count on that but
either way, the wet and active monsoon season looks to continue
through next weekend.

&&

.AVIATION...Valid through 20/00Z.
SCT-BKN clouds at 8k-12k ft MSL with BKN layers above til 19/07Z the
clouds slowly diminishing. SCT-NMRS SHRA/TSRA developing and
persisting through the evening hours mainly east and south of Tucson
before diminishing late tonight. Wind gusts to 45 kts possible near
any TSRA along with MVFR conditions and mountain obscurations due to
heavy rain. Otherwise, SFC wind generally less than 12 kts. Aviation
discussion not updated for TAF amendments.

&&

.FIRE WEATHER...A wet monsoon pattern will continue through the
coming work week resulting in scattered showers and thunderstorms.
The convection will be primarily during the afternoon and evening
hours but will be possible at anytime of the day or night. Primary
concerns outside of the typical gusty winds is potential flooding due
to heavy rains. Afternoon temperatures will remain below normal
through the coming week with higher than average humidity levels
continuing.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch until midnight MST tonight for AZZ503-506>509-
511>514.

&&

Public...Cerniglia
Aviation...Cerniglia
Fire Weather....Cerniglia

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Special Weather Statement
National Weather Service Tucson AZ
410 PM MST Sun Jul 18 2021

AZZ508-512-182345-
Chiricahua Mountains including Chiricahua National Monument-Eastern
Cochise County Below 5000 Feet including Douglas/Willcox-
410 PM MST Sun Jul 18 2021

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

At 410 PM MST, Doppler radar was tracking a strong thunderstorm 12
miles north of Chiricahua National Monument, or 17 miles west of
Steins, moving north at 10 mph.

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

Locations impacted include...
San Simon.

LAT...LON 3215 10918 3213 10937 3233 10948 3235 10921
TIME...MOT...LOC 2310Z 162DEG 9KT 3219 10929

AH

Special Weather Statement
National Weather Service Tucson AZ
506 PM MST Sun Jul 18 2021

AZZ508-509-190045-
Upper Gila River and Aravaipa Valleys including
Clifton/Safford-Eastern Cochise County Below 5000 Feet including
Douglas/Willcox-
506 PM MST Sun Jul 18 2021

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHEASTERN GRAHAM...
NORTHEASTERN COCHISE AND SOUTHEASTERN GREENLEE COUNTIES UNTIL 545 PM
MST...

At 505 PM MST, Doppler radar was tracking a strong thunderstorm 17
miles northwest of Steins, moving west at 25 mph.

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

This storm will remain over mainly remote areas of southeastern
Graham, northeastern Cochise and southeastern Greenlee Counties.

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 3231 10944 3276 10940 3264 10905 3230 10905
TIME...MOT...LOC 0005Z 074DEG 27KT 3244 10915

KG