Severe Thunderstorm Warning 58, NWS Phoenix, AZ

416 
WWUS55 KPSR 132355
SVSPSR

Severe Weather Statement
National Weather Service Phoenix AZ
455 PM MST Fri Aug 13 2021

AZC007-013-021-140015-
/O.CON.KPSR.SV.W.0058.000000T0000Z-210814T0015Z/
Gila AZ-Maricopa AZ-Pinal AZ-
455 PM MST Fri Aug 13 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 515 PM MST
FOR GILA...MARICOPA AND PINAL COUNTIES...

At 455 PM MST, a severe thunderstorm was located near Miami, or 9
miles northwest of Globe, moving west at 20 mph.

HAZARD...Ping pong ball size hail and 60 mph wind gusts.

SOURCE...Radar indicated.

IMPACT...People and animals outdoors will be injured. Expect hail 
         damage to roofs, siding, windows, and vehicles. Expect wind 
         damage to roofs, siding, and trees.

Locations impacted include...
Globe, Superior, Miami, Central Heights-Midland City,
Top-Of-The-World, Claypool and Inspiration.

This includes the following highways...
US Highway 60 between mile markers 227 and 253.
AZ Route 70 near mile marker 253.
AZ Route 177 near mile marker 167.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

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

&&

LAT...LON 3336 11074 3323 11108 3350 11119 3353 11078
TIME...MOT...LOC 2355Z 089DEG 15KT 3345 11093 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.50 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

SDB

Area Forecast Discussion
National Weather Service Phoenix AZ
329 PM MST Fri Aug 13 2021

.SYNOPSIS...
High levels of moisture will remain entrenched across the region
into early next week, leading to persistent chances for showers
and thunderstorms. The primary threats with any storms remain
localized heavy rainfall that may cause flash flooding. A Flash
Flood Watch is in effect for south-central Arizona through Sunday
afternoon. Strong winds and some blowing dust will also be
possible for desert locations. With increased cloud cover and
showers, temperatures will remain near to below normal.

&&

.DISCUSSION...
It was a quieter start to the morning today compared to previous
mornings this week that have experienced heavy rainfall and flash
flooding. However, the quiet weather experienced across the forecast
area so far today will continue to change going through the
afternoon and evening with a moist and unstable airmass still in
place. The moist airmass is reflected on this morning's 13.12Z PHX
sounding, recording a PWAT value of 1.87", which is above the 90%
moving average of sounding climatology. In terms of the current
pattern, objective analysis shows an area of high pressure
situated over Utah while an area of low pressure remains situated
over New Mexico. The placement of these features will put parts of
Arizona under enhanced east/northeast flow aloft and difluence.
This will aid in enhancing the thunderstorm potential going
through this evening.

Current radar imagery shows thunderstorms continue to develop
along the Mogollon Rim and across southeast Arizona, while visible
satellite shows a cumulus field over much of south-central
Arizona. The environment in place remains unstable with SPC
mesoanalysis showing MLCAPE values upwards of 1,000-2,000 J/kg
across much of the region. The ingredients in place suggest the
potential for a pretty active afternoon and evening across the
region, though model guidance show uncertainty in how convection
will evolve. HREF guidance shows the activity along the Rim
increasing in coverage and pushing further into southern Gila
County this afternoon with the potential for thunderstorms to
become more organized with increased shear. Thunderstorms will be
capable of producing heavy rainfall, which could result in flash
flooding especially for burn scar areas. A Flash Flood Watch
remains in effect for southern Gila County, which includes the
burn scar areas, and Maricopa County through Sunday. Other
impacts with these storms will be strong to perhaps severe winds
and hail.

Going into this evening, HREF paintball plots show thunderstorms
moving into the lower elevations. Guidance shows uncertainty in how
the coverage of this convection will evolve as it pushes into the
lower deserts this evening with some guidance suggesting a line of
storms pushing through while others suggest a break in the line
across south-central Arizona. Storms will be capable of producing
strong to severe winds as they push through with HREF guidance
showing around a 70% chance of winds exceeding 35 mph and 10% chance
of winds exceeding severe criteria. SPC has much of the state under
a marginal risk of severe weather for damaging winds. One limiting
factor for stronger winds will be limited DCAPE as values are
expected to remain around 1,000 J/kg. Thunderstorm activity is
expected to decrease as they progress further into southwest Arizona.

.PREVIOUS DISCUSSION...

After an active Friday night, Saturday would typically be thought
to be a "down" day. That may not necessarily hold as the enhanced
northeasterly mid level flow remains in place and the pattern is
conducive to mountain-valley propagating storms. On Sunday, a mid
level front moving out of NM and into AZ may push enough
dry/capping air in from the Four Corners to pair the heavy rain
threat a bit but the increased dry air may lead to a higher wind
threat. Ultimately a similar pattern continues Monday and Tuesday,
before a broader realignment mid-week. Global ensembles are still
moving a trough through the Pacific Northwest starting Wednesday.
While a deep, closed trough is not favored by the majority of
members, we should see a mid/upper level southwest flow develop
which will begin shunting the moisture in place east. Many members
do generate additional around Wednesday, perhaps indicating there
will be shortwave energy that lifts through our area on the
increasing southerly flow. PoPs begin to trend down thereafter.

Across southwest Arizona, the potential for isolated
thunderstorms and decaying large outflows will continue most days.
Even a couple of desert mountain thunderstorms could develop
across southeast California any of the days given the humid
boundary layer.

With more sun, temperatures will remain fairly close if not a
little above normal across southeast California and near normal
toward Yuma. Further east, temperatures will remain below normal
for the Phoenix area. Thursday did briefly sneak up to 100F and
temperatures in the upper 90s to near 100 look to be common
through the next week.

&&

.AVIATION...Updated at 1840Z.

South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:

Normal diurnal wind trends are favored for the afternoon and
early evening. Then good chances develop for storms to affect the
area during the evening hours. HREF/members depict an organized
line of storms descending into the Phoenix area from the Rim
with enhanced chances for very strong winds and heavy rain. The
best chances for the storms to enter the Valley this evening will
be between 03-06Z and this is reflected in the TAFs with gusty
easterly winds and VCTS along with low storm cloud CIGs of 6-8
kft. Outside of storms expect BKN mid cloud CIGs of 10-15 kft.

Southeast California/Southwest Arizona including KIPL and KBLH:

At KIPL, light westerly downslope winds are expected to continue
through the morning, then become breezy with gusts upwards of 20
kt this evening. Winds at KBLH will alternate between SW to SE at
5-10 kts. Otherwise skies will be partly cloudy with FEW-SCT mid-
high clouds. Storm chances at KBLH are near 10% and less than 5%
at KIPL.

&&

.FIRE WEATHER...
Sunday through Thursday:
Generally an active weather period will continue with persistent
chances for showers and thunderstorms, with the best chances
across southern Gila county decreasing as one goes west. Humidity
values themselves will remain quite elevated during this period,
with overnight values rising into the 50-90% range and daytime
values falling only 25-45% range. A modest drying trend may being
at the very end of the forecast period. Winds will favor typical
diurnal/terrain influences most days.

&&

.SPOTTER INFORMATION STATEMENT...
Spotters should follow standard reporting procedures.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Flash Flood Watch through Sunday afternoon for AZZ534-537>563.

CA...None.
&&

DISCUSSION...Smith
PREVIOUS DISCUSSION...Iniguez
AVIATION...Sawtelle/Kuhlman
FIRE WEATHER...Iniguez

Special Weather Statement
National Weather Service Phoenix AZ
250 PM MST Fri Aug 13 2021

AZZ558-560-562-563-132230-
Southeast Gila County AZ-San Carlos AZ-Globe/Miami AZ-
Pinal/Superstition Mountains AZ-
250 PM MST Fri Aug 13 2021

...A strong thunderstorm will impact portions of Gila County through
330 PM MST...

At 249 PM MST, Doppler radar was tracking a strong thunderstorm near
San Carlos, or 13 miles east of Globe, moving southwest at 5 mph.

HAZARD...Wind gusts of 50 to 55 mph and nickel size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
Globe, San Carlos, Cutter, Hilltop and Peridot.

This includes the following highways...
US Highway 60 between mile markers 253 and 259.
AZ Route 70 between mile markers 254 and 271.

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.

&&

LAT...LON 3343 11030 3344 11032 3340 11035 3340 11041
      3339 11042 3339 11044 3330 11045 3319 11060
      3345 11080 3363 11042 3344 11026
TIME...MOT...LOC 2149Z 054DEG 4KT 3340 11055

MAX HAIL SIZE...0.88 IN
MAX WIND GUST...55 MPH

SDB

Special Weather Statement
National Weather Service Phoenix AZ
414 PM MST Fri Aug 13 2021

AZZ558-560-562-563-140000-
Southeast Gila County AZ-San Carlos AZ-Globe/Miami AZ-
Pinal/Superstition Mountains AZ-
414 PM MST Fri Aug 13 2021

...A strong thunderstorm will impact portions of Gila County through
500 PM MST...

At 413 PM MST, Doppler radar was tracking a strong thunderstorm near
Cutter, or 8 miles east of Globe, moving west at 15 mph.

HAZARD...Wind gusts of 50 to 55 mph and nickel size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
Globe, Miami, Cutter, Central Heights-Midland City, Claypool and
Inspiration.

This includes the following highways...
US Highway 60 between mile markers 241 and 263.
AZ Route 70 between mile markers 253 and 263.
AZ Route 77 between mile markers 162 and 170.

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.

&&

LAT...LON 3354 11057 3337 11052 3321 11086 3351 11097
TIME...MOT...LOC 2313Z 074DEG 12KT 3344 11065

MAX HAIL SIZE...0.88 IN
MAX WIND GUST...55 MPH

SDB