Severe Thunderstorm Warning 24, NWS San Diego, CA

894 
WWUS56 KSGX 090120
SVSSGX

Severe Weather Statement
National Weather Service San Diego CA
620 PM PDT FRI SEP 8 2017

CAC065-090145-
/O.CON.KSGX.SV.W.0024.000000T0000Z-170909T0145Z/
Riverside CA-
620 PM PDT FRI SEP 8 2017

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 645 PM PDT
FOR RIVERSIDE COUNTY...

At 613 PM PDT, a severe thunderstorm was located near Thermal, 
moving northeast at about 10 mph. Winds at Thermal Airport gusted to 
62 mph at 546 PM. 

HAZARD...60 mph wind gusts and penny size hail. 

SOURCE...Radar indicated. 

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

Locations impacted include...
Indio, Coachella, Thermal, La Quinta, Mecca and Santa Rosa Mountain. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of 
a building if possible. Gusty, erratic winds may also affect travel 
through the area.

&&

LAT...LON 3351 11597 3352 11605 3351 11605 3350 11608
      3345 11604 3343 11603 3343 11624 3378 11625
      3378 11605 3374 11600 3374 11595 3352 11595
TIME...MOT...LOC 0113Z 239DEG 28KT 3366 11578 

HAIL...0.75IN
WIND...60MPH
 
$$

Small

870 
WWUS56 KSGX 090144
SVSSGX

Severe Weather Statement
National Weather Service San Diego CA
644 PM PDT FRI SEP 8 2017

CAC065-090148-
/O.EXP.KSGX.SV.W.0024.000000T0000Z-170909T0145Z/
Riverside CA-
644 PM PDT FRI SEP 8 2017

...THE SEVERE THUNDERSTORM WARNING FOR RIVERSIDE COUNTY WILL EXPIRE
AT 645 PM PDT...
    
The severe thunderstorm which prompted the warning has weakened.
There could still be some gusty, erratic winds and localized reduced 
visibilities in dust, otherwise the severe thunderstorm warning for 
the area near Indio, Thermal, and Mecca will be allowed to expire.

LAT...LON 3351 11597 3352 11605 3351 11605 3350 11608
      3345 11604 3343 11603 3343 11624 3378 11625
      3378 11605 3374 11600 3374 11595 3352 11595
TIME...MOT...LOC 0138Z 239DEG 28KT 3373 11564 

$$

Small

Area Forecast Discussion
National Weather Service San Diego CA
156 PM PDT Fri Sep 8 2017

.SYNOPSIS...
A trough of low pressure will bring cooler weather through
Saturday, but also moisture for some thunderstorms during
afternoons and early evenings in the mountains and deserts. The
moisture flows westward Sunday over the entire region for
widespread showers and thunderstorms in all areas. Dry and
seasonal weather will develop Monday and continue the rest of next
week while coastal clouds increase.

&&

.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...

A lot of elevated convective clouds cover the sky leading to
isolated sprinkles around San Diego and inland. Legit thunderstorms
have erupted in the Imperial Valley and will get going in our
mountains and lower deserts this afternoon. Moisture has moved up
from Mexico into the SE CA desert, but the moisture gradient is
sharp toward the west and continues this way through Saturday. So
thunderstorms are a good bet in the mountains and deserts during
the afternoons through Saturday, but probably not farther west
into valleys or even into the San Gabriel Mountains. The onshore
flow will weaken with the monsoon push, so coastal low clouds will
be on the decline this weekend. What's behind all this? A low
pressure trough along the west coast has created southerly flow
drawing in the monsoon moisture from Mexico. The trough cuts off
into a compact low just off the California coast. By Sunday the
cutoff low goes far enough south that the flow over Southern
California becomes southeast, enough to draw that moisture
northwest. That's why we're forecasting chances of showers and
thunderstorms everywhere on Sunday. On Monday the cutoff low
shifts slightly north and turns off the monsoon tap by drawing in
drier air from the southwest. The chances of precip shift north
and go away entirely by Monday night. The low opens up and the jet
stream nudges it eastward Tuesday and Wednesday. Dry air will
preclude any precip and the marine layer will be able to recover
and gain strength Tuesday and Wednesday. The increasing onshore
flow will probably create some brisk winds in the mountains and
deserts as well. On Wednesday enough dry air could combine with
winds for some critical fire weather conditions. A weak trough
pattern seems to remain for the latter half of next week for
seasonal weather absent of the tropical moisture influence.

&&

.AVIATION...
092005Z...Coast/Valleys...Through 09/0200 UTC, P6SM vis and SCT-BKN
clouds AOA 9000 ft msl. 09/0200-1500 UTC, stratus moving inland 15-
20 sm, with bases around 1000-1500 ft msl, tops around 1500-1800 ft
msl, and areas of vis 1-5 sm along higher coastal terrain/inland
mesas. Forecast marine layer inversion strength of around 8 deg C at
09/1200 UTC. Elsewhere, P6SM vis and FEW-SCT clouds AOA 10000 ft msl
will continue.

Mountains/Deserts...ISOL/SCT TSRA will likely develop through
09/0200 UTC with CB bases near 10000 ft MSL and tops to 40000 ft
MSL. Otherwise, SCT-BKN clouds AOA 10000 ft msl and P6SM vis will
prevail through Saturday morning.

&&

.MARINE...
There is a slight chance of thunderstorms Sunday over the coastal
waters due to a cut-off low pressure system near Point Conception
bringing up moisture and instability over the region. Otherwise,
expect wave heights through Sunday of 3-5 ft, then down to 2-3 ft
Monday through Wednesday, with weak to moderate northwest winds
through the period.

&&

.SKYWARN...
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...NONE.

&&

PUBLIC...MM
AVIATION/MARINE...Harrison