Severe Thunderstorm Warning 9, NWS Phoenix, AZ

Area Forecast Discussion
National Weather Service Phoenix AZ
505 PM MST Sat Jun 25 2022

.UPDATE...Updated 00z Aviation Discussion

.SYNOPSIS...
With sufficient moisture in place, shower and thunderstorm
opportunities will persist over much of the region with better
chances entering the picture Sunday and Monday. Storms will have the
potential to produce frequent lightning, brief heavy downpours,
gusty winds, and localized blowing dust. Temperatures will remain
seasonally warm, albeit still near average with lower elevation
afternoon highs still regularly eclipsing 100 degrees.

&&

.DISCUSSION...
Objective analysis shows a stable pattern configuration across the
Conus with expansive subtropical ridging aligned over the entire
southern tier of states. With the central H5 positive height anomaly
situated over the lower Mississippi River Valley, a westward
extension of the ridge axis was situated along the Arizona
international border. Along this western periphery, satellite
imagery clearly depicts a nearly stationary MCV spinning over far SE
Arizona with residual moisture encompassing the majority of the
circulation. The larger synoptic pattern next week will generally
feature retrogression in the lower latitudes with more pronounced
high pressure and more frequent subsidence migrating westward
towards the SW Conus, however it will be these convectively
enhanced, sub-synoptic features and interactions similar to this
mornings MCV that will largely dictate daily storm potential and
evolution.

The aforementioned SE Arizona MCV should meander along the
international border through this evening leading to forced ascent
in advance of the circulation center through far southern AZ.
Entrained midlevel moisture rotating across the eastern CWA this
morning has temporarily restricted instability growth while
bolstering CinH. While this may not be the case the entire day as
clouds erode, the best instability corridor and prime area for
convective initiation as supported by a vast majority of CAMs
aligns from western Pima County through southern Maricopa and
central Yuma and La Paz counties. This includes traditional
initiation points such as Table Top Wilderness and the Kofa
mountains. Objective analysis already indicates MLCApe nearing 1000
J/kg while DCape exceeds 2000 J/kg suggesting any storms forming in
this region later will easily have the potential for strong, gusty
winds and localized blowing dust impacts. Around the Phoenix metro,
the convective environment does not appear as impressive with
boundary layer mixing ratios still hovering around 8-9 g/kg. While
this does not completely preclude thunderstorm development, much
like last evening, multiple colliding outflow boundaries will be
needed to further moisten and dislodge the boundary layer from a
capped scenario.

HREF membership seems in quite good agreement depicting a better
defined vorticity center propagating north out of Sonora Sunday
afternoon acting upon an unstable, and only marginally capped
environment. The prospect for multiple, deeper outflows capable of
triggering deep convection at lower elevations increases markedly as
mixing ratios edge towards 10 g/kg. Not surprisingly, NBM POPs are
notably higher across much of Arizona Sunday evening solidly in a 20-
50% range, even over lower elevations. The primary thunderstorm
impacts will remain similar to the past couple days (i.e. lightning,
gusty outflow winds, and blowing dust) given a similar thermodynamic
structure, just with likely more extensive coverage.

Daily details with respect to thunderstorm formation and coverage
much of next week will be driven by mesoscale influences versus any
larger scale forcing mechanisms. As previously mentioned,
retrogression of the high pressure center will bring the anti-
cyclone center into the Southwest region during the middle/end of
the week, however the vast majority of ensembles keep H5 heights
tempered near 594dm (quite typical for late June) such that the high
pressure induced subsidence should not be the main influence in
determining convective formation and coverage. One key may be the
ultimate location of the pressure ridge: some ensembles build the
ridge into northern AZ which becomes a convectively favorable deep
easterly flow over much of the forecast area while other ensemble
members focus the ridge over northern Mexico/southern Arizona which
would be less convectively encouraging. Regardless of the exact
position, the fact is moisture depth and magnitude have already
become established over the region such that there shouldn't be any
day completely devoid of storms (at least until moisture is more
thoroughly scoured from the area). Rather, the forecast challenge
any given day will hinge on whether storms remain isolated over
mountains or whether salient mesoscale feature support and/or force
convective sustenance into lower elevations. Thus, the official
forecast much of the week is nearly a persistence forecast with
model trends inching towards lesser storm coverage and impacts late
in the week.

&&

.AVIATION...Updated at 0005Z.

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

The main weather concern into this evening remains to be gusty
outflow winds and abrupt wind shifts from distant thunderstorms that
have developed to the north and east of Phoenix. Right now it
appears that this outflow will reach the terminals around 00Z. Wind
gusts as high as 30-35kts are indicated at the current time on 88-D
radar imagery. Given the direction the outflow is coming from,
blowing dust should not be a significant problem, but cannot rule
out visibilities briefly falling to around 3-5SM. There remains about
a 20% chance of shower or thunderstorms affecting the terminals.
Therefore, confidence is low to include anything more than VCSH in
the TAFs at this time. Once the outflow boundaries/convective
activity pass through the area by mid- evening, winds will
predominate from an easterly direction thru the rest of the night
and thru much of Sunday. A more active day appears to be on tap for
Sunday as moisture increases over the region. Current thinking is
that showers/t-storms will begin to move into the Phx area during
the early evening hours with a brief period of southwesterly winds
becoming easterly as the storms move into the region. Right now,
looking at about a 70% chance of winds over 35 kts and 10-15% chance
of winds of 50 kts or great and a 30-40% chance of thunderstorms
impacting one or more of the terminals.

Southeast California/Southwest Arizona including KIPL and KBLH:
Mostly quiet weather will exist through Saturday evening under clear
skies At KIPL, southeasterly winds to become westerly sundowner
winds of around 10 kts through the evening hours, switching to light
southeasterly winds overnight and thru Sunday. At KBLH, southerly
winds of around 10 kts are expected through the period.

&&

.FIRE WEATHER...
Moisture will remain entrenched across most districts through much
of next week with the greatest afternoon thunderstorm and wetting
rain chances focused over higher terrain locations north and east of
Phoenix. However, even lower desert communities may occasionally
experience wetting rainfall at times - more likely early in the
week. Minimum afternoon humidity levels will generally fall in a 15-
30% range with somewhat lower values in far western districts.
Overnight recovery will be poor to fair in lower elevations (20-40%)
and good over eastern district high terrain locations (40-70%).
Aside from occasional late afternoon/early evening thunderstorm
downburst and/or outflow winds, winds should not be a significant
impact.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.

&&

DISCUSSION...18
AVIATION...Hodges/Lojero
FIRE WEATHER...18

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Special Weather Statement
National Weather Service Phoenix AZ
554 PM MST Sat Jun 25 2022

AZZ538-260145-
Tonopah Desert AZ-
554 PM MST Sat Jun 25 2022

...A strong thunderstorm will impact portions of Maricopa County
through 645 PM MST...

At 554 PM MST, Doppler radar was tracking a strong thunderstorm near
Tonopah. This storm was nearly stationary.

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...
Buckeye and Tonopah.

This includes AZ Interstate 10 between mile markers 90 and 102.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

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.

&&

LAT...LON 3343 11298 3359 11306 3373 11282 3349 11267
TIME...MOT...LOC 0054Z 242DEG 4KT 3355 11290

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

SDB

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE PHOENIX AZ
626 PM MST SAT JUN 25 2022

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

0515 PM     NON-TSTM WND GST 3 NNW MESA              33.45N 111.84W
06/25/2022  E45 MPH          MARICOPA           AZ   TRAINED SPOTTER

            SPOTTER ID MAA21 REPORTED THAT NEAR SR LOOP
            202 @ MCKELLIPS & DOWNTOWN MESA POWER POLE
            WIRES WERE DOWN LEADING TO MULTIPLE POWER
            OUTAGES.

&&

BF

Special Weather Statement
National Weather Service Phoenix AZ
627 PM MST Sat Jun 25 2022

AZZ537-538-540-260200-
Buckeye/Avondale AZ-Tonopah Desert AZ-Northwest Valley AZ-
627 PM MST Sat Jun 25 2022

...A strong thunderstorm will impact portions of Maricopa County
through 700 PM MST...

At 627 PM MST, Doppler radar was tracking a strong thunderstorm near
Perryville, or near Buckeye, moving northeast at 5 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...
Goodyear, Buckeye, Liberty, Perryville and White Tank Mountain Park.

This includes the following highways...
AZ Interstate 10 between mile markers 111 and 126.
AZ Route 85 between mile markers 152 and 154.
AZ Route 303 between mile markers 105 and 106.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

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 3333 11259 3348 11269 3362 11250 3340 11235
TIME...MOT...LOC 0127Z 240DEG 4KT 3346 11254

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

SDB

Special Weather Statement
National Weather Service Phoenix AZ
640 PM MST Sat Jun 25 2022

AZZ531-536-539-260230-
Gila River Valley AZ-Kofa AZ-Gila Bend AZ-
640 PM MST Sat Jun 25 2022

...Strong thunderstorms will impact portions of east central Yuma and
Maricopa Counties through 730 PM MST...

At 639 PM MST, Doppler radar was tracking strong thunderstorms
between Tacna and Sentinel. These storms were nearly stationary.

HAZARD...Wind gusts of 50 to 55 mph and pea 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...
Tacna, Sentinel, Paloma, Tyson, Dateland, Mohawk, Roll and Hyder.

This includes AZ Interstate 8 between mile markers 38 and 88.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

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

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

&&

LAT...LON 3314 11329 3303 11380 3290 11413 3259 11398
      3266 11354 3274 11315
TIME...MOT...LOC 0139Z 156DEG 2KT 3283 11334 3277 11366 3271 11400

MAX HAIL SIZE...0.25 IN
MAX WIND GUST...55 MPH

SDB