Scientific Forecaster Discussion
fxus66 ksgx 192101
Area forecast discussion
National Weather Service San Diego California
201 PM PDT Thu Apr 19 2018
drier weather for the rest of today, with gusty winds continuing
in the deserts. High pressure will take hold Friday and remain in
control through early next week, bringing quiet and warmer
weather to the region. Cooler to end next week with the potential
for a trough of low pressure along the West Coast.
Discussion...for extreme southwestern California including Orange...
San Diego...western Riverside and southwestern San Bernardino
At 130 PM, an upper level trough was centered over Nevada, with
cool northwest flow from the surface to 500 mb over socal. Rain
showers had ended over the region, with 0.01-0.05 inches of
accumulation from the mountain crests westward. Winds remained
gusty in the deserts, though significant blowing dust was not
evident on satellite.
Gusty winds will continue through tonight as mountain wave
activity mixes 30-45 kt 850-700 mb winds down to the surface. The
strongest winds are expected in the San Diego County deserts
where the core of an 850-700 mb jet will be perpendicular to the
terrain. Winds speeds should be limited to isolated 60 mph gusts
along the desert slopes, and 35-50 mph gusts on the desert floor.
Diminishing winds late tonight as mountain wave activity and mid
level support shift east along with the upper trough.
Weak ridging will develop over the region Friday and remain in
control through early next week. This will bring a rapid warming
trend to the region with afternoon highs returning to 5-10 degrees
above seasonal normals Saturday/Sunday. A weak closed low may
drift over the region Saturday night and Sunday, but impacts
should be limited to a few high clouds. Other than temperatures,
winds will be light, with no impactful weather forecast through
the early next week.
Global models continue hint at the development of a closed low
along the West Coast by late next week. The track/strength of this
low remains in question, with better agreement in recent runs of
the deterministic European model (ecmwf)/GFS being undercut by significant spread
in their corresponding ensembles.
192000z...coast/valleys...bkn-ovc clouds based around 3000-5000 feet
mean sea level with tops to 7000 feet mean sea level into the evening will give way to
mainly scattered clouds and unrestricted visibilities. The risk of
broken low clouds at ksan is low, so the confidence in mainly scattered
clouds in the ksan taf is high.
Mountains/deserts...areas of coastal slope and ridge obscurations
will occur through late tonight, mostly below 7000 feet mean sea level due to
clouds and fog. Isolated -shra with local -shsn will occur, but
slowly taper off. Areas of strong winds will continue, strongest
this evening from the desert slopes into the deserts. West winds 20-
30 knots, with isolated gusts 40-50 knots possible. Areas of reduced
vis below 3sm in blowing dust and sand are probable in deserts this
winds and choppy seas will peak this evening, mainly in the outer
waters, presenting a hazard for small craft. No additional hazardous
marine weather is forecast Friday through Monday.
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
California...High Wind Warning until 2 am PDT Friday for Coachella Valley-
Riverside County mountains-San Diego County deserts-San
Diego County mountains-San Gorgonio Pass near Banning.
Wind Advisory until 11 PM PDT this evening for apple and Lucerne
valleys-San Bernardino County mountains.
Pz...Small Craft Advisory until 2 am PDT Friday for coastal waters
from San Mateo Point to the Mexican border and out to 30 nm-
waters from San Mateo Point to the Mexican border extending
30 to 60 nm out including San Clemente Island.