Special Weather Statement, NWS Tucson, AZ

Area Forecast Discussion
National Weather Service Tucson AZ
152 PM MST Mon Aug 16 2021

.SYNOPSIS...Showers and thunderstorms will continue through the
afternoon and evening hours across the area, gradually diminishing
overnight. Heavy rain, flash flooding and severe thunderstorms are
the threats. More typical monsoon days are expected Tuesday and
Wednesday with most locations dry by Thursday into Saturday.
Temperatures will remain below normal for the next few days.

&&

.DISCUSSION...Our active afternoon and evening is starting to come
together across southeast Arizona. The ingredients are in place with
MLCAPE values 1500-2500 J/KG along with a favorable steering wind
profile, above normal moisture levels and broad lift ahead of a
shortwave trough moving south from the Four Corners region along the
AZ/NM border. KEMX radar is showing mostly terrain (and nearby
adjacent areas) convection which will transition into more
widespread storms as activity moves S/SW off the Mogollon Rim. SPC
has much of the CWA outlined in slight risk for severe
thunderstorms. Winds and hail will be the primary severe
thunderstorm threats and we've already seen nickel sized hail in
Oracle from an earlier thunderstorm. Otherwise, the storms initially
today will be fairly slow moving and produce very heavy rainfall
rates with the strongest storms producing more than 2 inches per
hour. Storm movement will increase slightly later but still very
heavy rainfall rates expected, especially in areas where cell
mergers take place as convection becomes more widespread. Thus, the
Flash Flood Watch continues to look good and remains in effect until
2 AM. Convection should generally push to the S/SW this evening and
tend to push southward across the international border after
midnight.

Considerable moisture will remain across southeast Arizona Tuesday,
the main question is just how widespread will potential convection
be. The atmosphere will likely be worked over from the storms
tonight which could limit development Tuesday. HREF members
indicated mostly scattered thunderstorm coverage and this seems
reasonable. PoPs are still fairly elevated but we went below NBM
guidance for Tuesday. Any thunderstorms on Tuesday may still result
in heavy rain and localized flash flooding given slow steering
motions.

As westerly to southwesterly flow kick more into gear Wednesday due
to an upper low across the Pac NW, the weak upper low west of Baja
at this time will get ejected eastward as a shortwave trough. Given
the W/SW flow, best thunderstorm chances on Wednesday will be from
Tucson eastward.

A bona fide break in the monsoon is expected later this week. There
could still be a few storms around in the White Mountains Thursday
but otherwise dry conditions are expected Thursday through Saturday
with drier air on westerly to southwesterly flow aloft. As the
subtropical high builds across the Gulf Coast states into Texas this
weekend, the flow will become more southerly by Sunday into early
next week.

Below normal temperatures will continue this week, warming up to
seasonable levels this weekend.

&&

.AVIATION...Valid through 18/00Z.
Scattered to numerous SHRA/TSRA will continue this aftn thru the
evening hours, gradually diminishing aft 17/06Z with more scattered
SHRA/TSRA psbl especially aft 17/18Z. Gusty winds up to 45+ kts are
psbl with these storms today, otrw expect sfc winds 10 kts or less.
Clouds will be SCT-BKN 6k-11k ft MSL thru the pd with ocnl MVFR
conds in SHRA/TSRA. Aviation discussion not updated for TAF
amendments.

&&

.FIRE WEATHER...The active monsoon continues through Wednesday
as a series of weather disturbances transition across the area and
plenty of moisture remains in place. Flash flooding along with
strong to severe winds and hail are the main threats this afternoon
and tonight. Thereafter, storm coverage will become more scattered
in nature with locally heavy rain the primary threat. By Thursday
into the weekend most locales should remain dry with isolated
thunderstorms mainly limited to the higher terrain of Graham and
Greenlee County Thursday. Below normal temperatures are expected
through mid-week before a gradual warm up begins late in the week.
Min RH values remain well above critical levels.
20-foot winds will generally be less than 15 mph when not influenced
by thunderstorms.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
 Flash Flood Watch through late tonight for AZZ501>515.

&&

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Special Weather Statement
National Weather Service Tucson AZ
314 PM MST Mon Aug 16 2021

AZZ509-510-162300-
Upper Gila River and Aravaipa Valleys including Clifton/Safford-White
Mountains of Graham and Greenlee Counties including Hannagan Meadow-
314 PM MST Mon Aug 16 2021

...A strong thunderstorm will impact portions of northeastern Graham
and west central Greenlee Counties through 400 PM MST...

At 313 PM MST, Doppler radar was tracking a strong thunderstorm 26
miles southeast of Seven Mile, or 39 miles northwest of Clifton,
moving south at 5 mph.

HAZARD...Wind gusts up to 50 mph.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects.

Locations impacted include...
Point-Of-Pines.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 3350 10963 3293 10941 3303 10979 3322 11003
      3349 10981 3347 10977 3348 10975 3351 10974
TIME...MOT...LOC 2213Z 006DEG 6KT 3346 10974

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...50 MPH

AH

Special Weather Statement
National Weather Service Tucson AZ
358 PM MST Mon Aug 16 2021

AZZ509-510-162345-
Upper Gila River and Aravaipa Valleys including Clifton/Safford-White
Mountains of Graham and Greenlee Counties including Hannagan Meadow-
358 PM MST Mon Aug 16 2021

...A strong thunderstorm will impact portions of central Graham and
southern Greenlee Counties through 445 PM MST...

At 358 PM MST, Doppler radar was tracking a strong thunderstorm 7
miles northeast of Safford Regional Airport, or 11 miles northeast of
Safford, moving south at 5 mph.

HAZARD...Wind gusts up to 50 mph.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects.

Locations impacted include...
Safford, Clifton, Thatcher, Solomon, Morenci, Roper Lake State Park,
Safford Regional Airport, Pima, Duncan, Central, York, Fort Thomas,
Franklin, Three Way, Guthrie and Swift Trail Junction.

This includes the following highways...
 Route 70 between mile markers 307 and 385.
 Route 75 between mile markers 379 and 398.
 Route 78 between mile markers 155 and 162.
 Route 191 between mile markers 115 and 175.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

A Severe Thunderstorm Watch remains in effect until midnight MST for
southeastern Arizona.

&&

LAT...LON 3282 11005 3327 10989 3300 10905 3258 10905
TIME...MOT...LOC 2258Z 006DEG 5KT 3295 10958

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...50 MPH

AH

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE TUCSON AZ
507 PM MST MON AUG 16 2021

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

0442 PM     HEAVY RAIN       34 SSW DUNCAN           32.25N 109.22W
08/16/2021  M0.80 INCH       COCHISE            AZ   TRAINED SPOTTER

            0.8 RAIN SINCE 1642 HRS. 2-3 INCHES OF WATER
            WITH MINOR FLOODING.

&&

JRM

Special Weather Statement
National Weather Service Tucson AZ
511 PM MST Mon Aug 16 2021

AZZ507-170045-
Upper San Pedro River Valley including Sierra Vista/Benson-
511 PM MST Mon Aug 16 2021

...A strong thunderstorm will impact portions of southwestern Cochise
County through 545 PM MST...

At 510 PM MST, Doppler radar was tracking a strong thunderstorm near
Whetstone, or 14 miles north of Sierra Vista, moving south at 15 mph.

HAZARD...Winds in excess of 40 mph.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects.

Locations impacted include...
Sierra Vista, Whetstone, Huachuca City, Fort Huachuca, Fairbank and
Charleston.

This includes the following highways...
 Route 82 between mile markers 52 and 63.
 Route 90 between mile markers 303 and 321.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

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

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

A Severe Thunderstorm Watch remains in effect until midnight MST for
southeastern Arizona.

&&

LAT...LON 3178 11036 3180 11018 3158 11010 3155 11035
TIME...MOT...LOC 0010Z 350DEG 14KT 3171 11027

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...40 MPH

Special Weather Statement
National Weather Service Tucson AZ
519 PM MST Mon Aug 16 2021

AZZ508-512-513-170100-
Dragoon/Mule/Huachuca and Santa Rita Mountains including
Bisbee/Canelo Hills/Madera Canyon-Chiricahua Mountains including
Chiricahua National Monument-Eastern Cochise County Below 5000 Feet
including Douglas/Willcox-
519 PM MST Mon Aug 16 2021

...A strong thunderstorms will impact portions of south central
Cochise County through 600 PM MST...

At 518 PM MST, Doppler radar was tracking a cluster of strong
thunderstorms about 14 miles southeast of Pearce-Sunsites, or 28
miles northeast of Bisbee, moving south at 15 mph.

HAZARD...Winds in excess of 40 mph.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects.

Locations impacted include...
Elfrida and McNeal.

This includes Route 191 between mile markers 17 and 36.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

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

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

A Severe Thunderstorm Watch remains in effect until midnight MST for
southeastern Arizona.

&&

LAT...LON 3184 10984 3187 10964 3159 10953 3156 10983
TIME...MOT...LOC 0018Z 350DEG 14KT 3179 10973

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...40 MPH

Special Weather Statement
National Weather Service Tucson AZ
536 PM MST Mon Aug 16 2021

AZZ508-509-511-512-170115-
Upper Gila River and Aravaipa Valleys including
Clifton/Safford-Chiricahua Mountains including Chiricahua National
Monument-Eastern Cochise County Below 5000 Feet including
Douglas/Willcox-Galiuro and Pinaleno Mountains including Mount
Graham-
536 PM MST Mon Aug 16 2021

...Strong thunderstorms will impact portions of southern Graham,
northeastern Cochise and southeastern Greenlee Counties through 615
PM MST...

At 536 PM MST, Doppler radar was tracking strong thunderstorms along
a line extending from 11 miles west of Thatcher to 17 miles northwest
of Steins. Movement was south at 10 mph.

HAZARD...Wind gusts up to 50 mph.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects.

Locations impacted include...
Safford, Thatcher, Solomon, Bowie, Roper Lake State Park, Pima,
Central, Swift Trail Junction, Fort Grant, Mount Graham, Bonita, San
Simon and Frye Mesa Dam.

This includes the following highways...
 Interstate 10 between mile markers 351 and 387.
 Route 70 between mile markers 314 and 344.
 Route 191 between mile markers 88 and 120.
 Route 266 between mile markers 105 and 126.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

A Severe Thunderstorm Watch remains in effect until midnight MST for
southeastern Arizona.

&&

LAT...LON 3202 10915 3267 11025 3297 10996 3255 10905
TIME...MOT...LOC 0036Z 013DEG 8KT 3283 10996 3242 10919

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...50 MPH

AH