Flash Flood Warning 36, NWS Phoenix, AZ

Area Forecast Discussion
National Weather Service Phoenix AZ
1035 AM MST Wed Jul 27 2022

.UPDATE...Updated Aviation Discussion...

&&

.SYNOPSIS...
A flood watch remains in effect for much of the area. An
abundance of moisture will allow any showers and storms that
develop to quickly produce copious amounts of rainfall. The
highest chances for showers and storms will reside over Arizona's
higher terrain today. Shower and thunderstorm chances will
increase over the lower deserts late this week and through the
weekend as waves of energy interact with humid conditions. High
temperatures will generally remain at or below normal, thanks to
this monsoon pattern.

&&

.DISCUSSION...
It's another generally cloudy night across the district. A few
showers are lingering at this late hour, but coverage is rather
sparse. A very weak mid-level disturbance continues to hang out
over C AZ. This is providing subtle lift over, essentially, a
tropical environment. Latest ACARS through PHX reveals a PW near
2" and MLCAPE <1000 J/kg, but there is some MLCIN from -50 to
-150 J/kg. Through the morning, isolated showers/storms could
develop essentially anywhere over SC/SE Arizona - particularly
around any outflow interactions. Locally heavy rain would be the
primary threat.

HREF members suggest that convective coverage today should reach
a relative nadir over the lower elevations; higher coverage is
anticipated across the higher terrain of Gila Co. With the
extremely moist profile, heavy rain/flash flooding is the primary
threat. Flood watch continues for much of La Paz, Gila, Pinal, and
Maricopa Counties. However, confidence in localized flash flood
threat is highest east of PHX before trailing off by the time you
get to SW La Paz Co. All of this lines up with the WPC day 1 SLGT
excessive rainfall risk area, which is highlighting areas just
east of Phoenix.

While there are some subtle changes in the pattern over the next
several days, you have to look closely to see them. The overall
setup is fairly stagnant: a moisture-laden troposphere is stuck in
place. Meanwhile, AZ will sit beneath weak cyclonic flow in the
mid-levels through at least the first portion of the weekend.
Lapse rates are unimpressive above the BL, so MLCAPE values will
range from 500-1500 J/kg most of the time.

One distinct wave of energy is readily apparent on WV this
morning just to the S of ELP. This feature is forecast to slowly
churn its way westward along the Intl Border between now and
Saturday, enhancing our PoPs from late Thu through Sat. After
coordination with neighboring offices, the flood watch has been
extended through Thursday night and may eventually be needed
beyond that time as well.

From Sunday into early next week, confidence is rather
undesirable as forcing mechanisms are essentially indiscernible
this far out in time. Ridging is forecast to amplify to our north,
and ample moisture will still reside across the region. Iso/Sct
storms remain in the forecast, and if we can pick up some
enhancement to the easterly mid-level flow, storm motions will
likely originate over the AZ high terrain before descending into
the lower deserts. All monsoon hazards will remain on the table.

MaxT's remain near (SE Cali) to below (elsewhere) normal for the
time of year through the period. At PHX, NBM probabilities give us
a daily 40% - 70% chance of remaining below 100F through Monday.

&&

.AVIATION...Updated 1735Z.

South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
After some nearby showers this morning, most of the showers and
isolated storms have shifted away from the terminals. Similar to
previous days, conditions remain favorable for pop up isolated
storms with heavy rainfall again later this afternoon into this
evening. Forecast confidence still remains low on whether any
storms will impacts the terminals, only around a 20 percent chance
right now. Something that will need to be monitored. Anticipating
another round of morning showers on Thursday, confidence enough
for VCSH late tonight through the morning. Otherwise, mainly
scattered mid clouds and scattered to broken high clouds will
persist through the forecast period.

Southeast California/Southwest Arizona including KIPL and KBLH:
Persistent southeast to south winds are expected at both
terminals. The terminals will see some scattered to broken high
clouds through the forecast period, but most of the storms are
currently expected to remain east of the area.

&&

.FIRE WEATHER...
MinRH values will feature a gradient from 25-35% over SW AZ and
SE CA to 30-45% near Phoenix and points eastward. Overnight
recovery will remain good, highest values (55% +) from PHX
eastward. Wetting rains will be concentrated mostly over high
terrain today. A flood watch is in effect for portions of La Paz
and all of Gila, Pinal, and Maricopa Co's through tonight. From
Thursday through early next week, rain/storm chances will be
highest over the Arizona high terrain (50-70%), lessening to
10-30% chances nearer to the CO Valley and SE Cali. Winds will
generally remain light, save for brief gusts near any stronger
storms.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Flood Watch through late Thursday night for AZZ533-534-537>563.

CA...None.
&&

DISCUSSION...Heil
AVIATION...Frieders
FIRE WEATHER...Heil

Special Weather Statement
National Weather Service Phoenix AZ
1144 AM MST Wed Jul 27 2022

AZZ537-541-542-271930-
Cave Creek/New River AZ-Deer Valley AZ-Northwest Valley AZ-
1144 AM MST Wed Jul 27 2022

...A strong thunderstorm will impact portions of Maricopa County
through 1230 PM MST...

At 1142 AM MST, Doppler radar was tracking a strong thunderstorm 7
miles northeast of Wittmann, moving southeast at 5 mph.

HAZARD...Winds in excess of 40 mph and heavy rainfall.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Heavy rainfall could cause localized
         flooding.

Locations impacted include...
Surprise, Wittmann, Sun City West, Beardsley, Lake Pleasant and
Vistancia.

This includes the following highways...
US Highway 60 between mile markers 129 and 139.
AZ Route 74 between mile markers 5 and 26.
AZ Route 303 between mile markers 119 and 123, and between mile
markers 126 and 134.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 3390 11232 3377 11219 3364 11247 3394 11260
      3396 11258
TIME...MOT...LOC 1842Z 331DEG 6KT 3386 11244

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

TF

Special Weather Statement
National Weather Service Phoenix AZ
1207 PM MST Wed Jul 27 2022

AZZ537-541-542-545-271945-
New River Mesa AZ-Cave Creek/New River AZ-Deer Valley AZ-
Northwest Valley AZ-
1207 PM MST Wed Jul 27 2022

...Strong thunderstorms will impact portions of Maricopa County
through 1245 PM MST...

At 1206 PM MST, Doppler radar was tracking strong thunderstorms along
a line extending from Rock Springs to near Lake Pleasant to near
Wittmann. Movement was southeast at 10 mph.

HAZARD...Winds in excess of 40 mph and heavy rainfall.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Heavy rainfall could cause localized
         flooding.

Locations impacted include...
Surprise, New River, Wittmann, Lake Pleasant, Vistancia and Anthem.

This includes the following highways...
AZ Interstate 17 between mile markers 220 and 241.
US Highway 60 between mile markers 128 and 136.
AZ Route 74 between mile markers 3 and 30.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 3402 11197 3371 11213 3370 11249 3388 11260
      3389 11228 3391 11224 3395 11224 3397 11219
      3405 11215
TIME...MOT...LOC 1906Z 320DEG 8KT 3404 11215 3384 11224 3383 11246

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

TF

Special Weather Statement
National Weather Service Phoenix AZ
103 PM MST Wed Jul 27 2022

AZZ541-545-547-549-272045-
Fountain Hills/East Mesa AZ-New River Mesa AZ-
Cave Creek/New River AZ-Rio Verde/Salt River AZ-
103 PM MST Wed Jul 27 2022

...A strong thunderstorm will impact portions of Maricopa County
through 145 PM MST...

At 101 PM MST, Doppler radar was tracking a strong thunderstorm near
McDowell Mountain Park, or 7 miles northeast of Scottsdale, moving
southeast at 15 mph.

HAZARD...Winds in excess of 40 mph and very heavy rainfall.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Heavy rainfall could produce localized
         flooding.

Locations impacted include...
Scottsdale, Fountain Hills, Rio Verde, McDowell Mountain Park and
Fort McDowell.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 3376 11193 3388 11177 3373 11156 3356 11174
TIME...MOT...LOC 2001Z 320DEG 19KT 3377 11179

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

TF