Scientific Forecaster Discussion
Area forecast discussion
National Weather Service San Diego California
900 PM PDT Thursday Sep 18 2014
a trough of low pressure will bring cooler weather through Sunday as
it moves across central California. Night and morning low clouds
will spread into the valleys each night...and the marine layer may
be thick enough to bring patchy drizzle late tonight through Friday
morning. There is a slight chance for thunderstorms over the
mountains Saturday afternoon. The trough moves east Sunday night
followed by a warming trend and shallower marine layer early next
Discussion...for extreme southwestern California including Orange...
San Diego...western Riverside and southwestern San Bernardino
The deepening trough along the West Coast brought significant
cooling west of the mountains today where temperatures were around
10 degrees lower than yesterday. The trough also lowered surface
pressures over the Great Basin where the gradients were about 5 mb
stronger than yesterday. Breezy/windy conditions will continue in
the mountains and deserts tonight where a Wind Advisory is in effect
for the Coachella Valley and the San Gorgonio Pass until 6 am
The prodigal stratus that had been absent at the coast for several
days has returned. Low clouds spread quickly into the San Diego
valleys this evening and may be thick enough for patchy drizzle west
of the mountains early Friday.
Friday will be even cooler with the trough transitioning into a
closed low near pt Conception. On Saturday the low slowly fills and
lifts northeast into central California. Models forecast a weak vorticity maximum to
drift over socal Saturday afternoon in broad cyclonic flow around
the upper low. Moisture is a limiting factor and there will only be
a slight chance for showers in the mountains Saturday afternoon. The
chances for even that to happen are quite low since most of the
moisture will remain over the eastern deserts.
Monday through Wednesday...weak ridging aloft will bring warming and
a shallower marine layer.
Wednesday through Friday...the ec and GFS show another deep trough
moving into California. If that scenario unfolds it would bring
another period of cooler than average weather...gusty mountains and
desert winds and a deep marine layer late next week.
190400z...coast/valleys...stratus will cover most areas west of the
mountains overnight with bases 1500-2500 feet mean sea level with tops to 3000 feet
mean sea level. Higher terrain will be locally obscured...but elsewhere most
visible will remain above 5 Michigan. Clearing will occur by 18z Friday in most
areas...except for local broken conditions near the coast Friday
afternoon. Stratus will spread inland again early Thursday evening.
Mountains/deserts...west winds with surface gusts 25-35 knots will continue
over the Desert Mountain slopes and adjacent deserts through 07z.
Otherwise...mostly clear skies with unrestricted visibilities will
continue through Friday night.
900 PM...no hazardous marine weather is expected through Tuesday.
900 PM...south-southwest swell will gradually lower overnight
through Friday. However...local surf of 3 to 5 feet will still occur
Friday on southwest facing beaches with occasional strong rip
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
California...Wind Advisory until 6 am PDT Friday for the Coachella Valley.