Scientific Forecaster Discussion
Area forecast discussion
National Weather Service San Diego California
839 PM PST Tue Dec 6 2016
gusty onshore winds over the mountains and deserts this evening will
weaken late tonight as low pressure moves east over The Rockies.
Weak offshore flow will follow for Wednesday into Thursday bringing
warming on Thursday and locally gusty northeast winds below the
Cajon Pass and near the Santa Ana Mountains Wednesday. A little
cooler Saturday...then a little warmer into early next week with
periods of high clouds at times.
Discussion...for extreme southwestern California including Orange...
San Diego...western Riverside and southwestern San Bernardino
Satellite imagery shows lots of high clouds over socal this evening,
but this is making it difficult to assess the low cloud situation.
Hi res models have insisted on developing some light showers over
the coastal foothills, but no reports of measurable rain have been
received and none is indicated on radar. The 00z Miramar sounding
showed a doubling of the marine layer depth to 3600 feet msl, and
continued southerly flow near 10 kts below.
At 8 PM PST...surface pressure gradients were increasing ksan to the
lower deserts at 5-6 mbs, but had dropped off to neutral ksan to SW
NV, after soaring to 9.5 mbs at 22z this afternoon. The net result
continues to be local wind gusts in the 45 to 55 miles per hour range along the
wind-prone desert slopes. A Wind Advisory is in effect for the
mts/deserts through late tonight.
A coastal eddy circulation will keep the marine layer elevated onto
the lower coastal slopes into Wed morning. Meantime, developing sfc
high pressure over the northern rockies will send winds back
offshore through the Cajon Pass and onto the o.C. Coastal plain on
Wed, resulting in clearing. Both high and low clouds will decrease
across the entire region by afternoon with minor warming expected as
a weak offshore pattern develops, forcing the marine layer back
offshore. Fair and dry conditions on Thu/Fri will bring further
The only weather concern will be for wind. NE winds through and
below the Cajon Pass could gust locally to around 35 miles per hour by midday
Wednesday, but should weaken into Thu morning. Mostly light winds
expected Thu/Fri. No changes to the current forecast.
From previous discussion...
Zonal flow continues late week with perhaps a slight perturbation
late Sat into sun. Have left this forecast dry, though European model (ecmwf) shows
some light quantitative precipitation forecast. However, the main story through the upcoming
weekend and into early next week is a continued quite regime.
Temperature wise, really no significant warming or cooling through
the period with seasonably cool weather expected to continue.
070330z...coast/valleys...variable clouds tonight, with bkn-ovc cigs
mostly 2500-3500 ft msl, clearing between 12z and 17z Wed. Expect
earlier clearing vcnty kont, ksbd and ksna and later clearing vcnty
ksan and kcrq. Local northeast winds 15-20 knots with gusts to 30
knots will occur in the Northern Island Empire, including vicinity
kont, kral, kcno, ksbd and inland Orange County near the Santa Ana
Mountains 15z-21z Wed.
Mountains/deserts...areas of strong west winds 20-30 knots with
local gusts to 50 knots will continue this evening, causing moderate
to strong up/down drafts and local low level wind shear over and east of the mtns.
Areas of terrain above 3500 ft mean sea level on the coastal slopes will be
obscured in clouds and fog through 12z Wed. Otherwise, variable
clouds at/above 15000 ft mean sea level will continue through Wednesday with
unrestricted vis above the terrain obscurations.
no hazardous marine weather is expected through Sunday.
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
California...Wind Advisory until 3 am PST Wednesday for apple and Lucerne
valleys-Riverside County mountains-San Bernardino County
mountains-San Diego County deserts-San Diego County
mountains-San Gorgonio Pass near Banning.