Severe Thunderstorm Warning 2, NWS Phoenix, AZ

961 
WWUS55 KPSR 092135
SVSPSR

Severe Weather Statement
National Weather Service Phoenix AZ
235 PM MST MON JUL 9 2018

AZC021-092145-
/O.CON.KPSR.SV.W.0002.000000T0000Z-180709T2145Z/
Pinal AZ-
235 PM MST MON JUL 9 2018

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 245 PM MST
FOR PINAL COUNTY...

At 234 PM MST, a severe thunderstorm was located over Boyce Thompson
Arboretum, or near Superior, and is nearly stationary.

HAZARD...60 mph wind gusts.

SOURCE...Radar indicated.

IMPACT...Expect damage to roofs, siding, and trees.

Locations impacted include...
Superior, Florence Junction, Queen Valley and Boyce Thompson
Arboretum.

This includes the following highways...
US Highway 60 between mile markers 213 and 228.
AZ Route 79 between mile markers 145 and 150.
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.

&&

LAT...LON 3333 11108 3318 11112 3318 11136 3338 11131
TIME...MOT...LOC 2134Z 104DEG 3KT 3329 11119 

HAIL...<.75IN
WIND...60MPH
 
$$

18

Area Forecast Discussion
National Weather Service Phoenix AZ
844 AM MST Mon Jul 9 2018

.UPDATE...
Updated Aviation Discussion.

&&

.SYNOPSIS...
Monsoon moisture levels will continue to remain high enough this
week to bring daily thunderstorm chances to the bulk of the region.
An upper level trough moving through today and early Tuesday
should enhance monsoon activity creating better chances for more
widespread storms than a typical monsoon day. Temperatures will
continue to trend downward through the middle of the week and then
level off a few degrees below normals.

&&

.DISCUSSION...
Monsoon activity on Sunday was a bit underwhelming for the
Phoenix area, but it ended up quite active across far southern
Arizona and southeast California. Showers and isolated
thunderstorms are still ongoing early this morning, but they
should begin to wind down by sunrise. The elongated upper level
high to our north is currently shifting to the northeast while a
distinct upper level wave is seen moving westward across New
Mexico. This upper level wave is a bit stronger than we typically
see this time of year with a closed low seen at 250/300mb and a
50kt northeasterly jet max on the western edge of the low.
Moisture across the region is also a bit atypical with high PWATs
of 1.5-1.8" from Phoenix westward to below 1" across far eastern
Arizona and western New Mexico.

Current water vapor imagery continues to show dry air getting
advected out ahead of the upper level low which is situated
across the eastern half of New Mexico. Eventually this dry air tap
will get pinched off later today, but as with yesterday eastern
Arizona will see PWATS mostly around 1". This area of drier air
will likely hinder high terrain storm development somewhat, but
the upper level enhancement from the incoming trough may be enough
to overcome the lower instability. Initial storm development
early to mid afternoon should focus first along the Mogollon Rim
and then across southeast Arizona as the upper level low moves
over the area. Winds aloft will be stronger than normal yielding
0-6km Bulk Shear of 20-35kts and CAPE should be a healthy
500-1000J/kg. More than sufficient moisture levels will exist
over the deserts, but a fairly dry sub-cloud layer will still be
in place resulting in modest to high DCAPE values. All this should
make for a rather active monsoon day with the potential for a few
severe wind producing storms and a decent probably of widespread
blowing dust. An easterly steering flow of 10-15kts will be high
enough to keep flood impacts on the lower side, but localized
flooding still could be a problem in a few areas given the higher
then typical moisture levels over the deserts. Timing is still a
bit difficult, but storm activity should affect the Phoenix area
sometime late this afternoon and early evening before moving
westward into the Lower Colorado River Valley by mid to late
evening.

For Tuesday and Wednesday, moisture levels will remain a bit
higher than typical monsoon levels, but we will lose the support
of the upper level low. Steering flow will also weaken and become
a bit more southerly resulting in slower moving storms and a higher
probability of flooding. Moisture levels peak on Wednesday and
forecast soundings show CAPE values rising to above 1000 J/kg. At
this point it seems either day could be rather active, but it may
depend on how much the previous day's activity affects the
atmosphere. Am currently leaning toward Wednesday being a bit more
active given the higher forecast instability and that storms Tuesday
may be dampened some if today ends up being quite active.

Late this week into the weekend the forecast becomes more
challenging as the upper level high reorientates itself over the
Great Basin while the flow over the Desert Southwest is very
weak. Moisture levels should remain at or maybe even above typical
monsoon levels, so chances for storms should be there each day.
One thing to note is that the GFS and the European deviate quite a
bit on moisture levels with the GFS trending lower while the
European remains above typical monsoon levels.

Temperatures over the next week will be trending downward, but
will be heavily dependent on the day to day monsoon activity and
cloud cover. Daily highs should remain at or below normal levels
with overnight lows near or slightly above normals.

&&

.AVIATION...
South-Central Arizona including KPHX, KIWA, and KSDL:
Leftover dust from last night's storm will continue to cause
decreased slantwise visibility through the morning with only slow
improvement. Surface winds will be light and variable. Expect
another round of storm activity to affect the metro area today but
much earlier than yesterday. In fact, anticipate outflow-producing
storms to begin affecting eastern portions of metro by 21Z. A lot
of uncertainties remain in terms of how widespread the activity
will be and whether or not any given TAF site will have TSRA on
top of the airfield. At a minimum, expect outflows to cause
significant wind shifts this afternoon and probably into the
evening.

Southeast California/Southwest Arizona including KIPL and KBLH:

Lingering lofted dust will continue to cause reduced slantwise
visibility through the morning with only slow improvement. Mid to
high clouds will continue through the morning before exiting to
the west. Anticipate at least isolated thunderstorm development
for tonight (very little before 00Z) with best chances east of the
Lower Colorado River Valley.

Aviation Discussion not updated for amended TAFs.

&&

.FIRE WEATHER...
Wednesday through Sunday:
With continued favorable Monsoon conditions, expect good chances
of thunderstorms, including periods of wetting rains. Expect min
RH values generally in the mid 20s to low 30 percent range across
the region to fall only slightly by Friday. In addition to any
gusty thunderstorm winds, expect rather typical Monsoon season
winds with significant variability with gusty periods. Overnight
recovery will be good to excellent.

&&

.SPOTTER INFORMATION STATEMENT...
Spotters may be needed late this afternoon and evening.

&&

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

DISCUSSION...Kuhlman
AVIATION...AJ
FIRE WEATHER...Sawtelle

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE PHOENIX AZ
923 AM MST MON JUL 9 2018

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

1030 PM     TSTM WND DMG     GILA BEND               32.95N 112.71W
07/08/2018                   MARICOPA           AZ   TRAINED SPOTTER

            DELAYED REPORT: DOWNED POWER LINES AND
            UPROOTED TREE. HALF THE TOWN STILL WITHOUT
            POWER AND TELEPHONE LANDLINE SERVICE.
            ESTIMATED TIME: 10:25-11:00 PM MST.

&&

JS