Scientific Forecaster Discussion
Area forecast discussion
National Weather Service San Diego California
850 PM PST Friday Dec 20 2013
a cool...dry...northerly flow will prevail aloft over California
through Saturday...slowly relenting as high pressure over the
eastern Pacific expands over the region. Weak offshore flow will
develop at the surface...and persist much of next week...pushing
daytime temperatures back above normal. Marine clouds will be
limited...but patches of high clouds will drift over the region at
times. Winter officially begins at 9:11 am PST tomorrow morning.
Discussion...for extreme southwestern California including Orange...
San Diego...western Riverside and southwestern San Bernardino
Areas of low clouds persisted west of the mountains this evening...and
patchy...thin...high clouds were drifting south over the state.
Surface pressure gradients were weak and winds generally light. The
00z Miramar sounding had strong northerly flow above 5k feet and 5-12
degrees c of warming...however only modest warming was indicated
below 800 mbs with little drying.
Looks like the rain and snow we experienced yesterday will be the
last for awhile. Socal will remain locked in a dry pattern through
next week with a strong high pressure ridge aloft parked over the
eastpac...and a cold trough over the lower 48. At the surface...a
broad but weak area of high pressure will dominate the west after
Sat...helping force weak to locally moderate offshore flow at times.
The offshore flow will lower humidity and result in additional
warming west of the mountains toward the coast.
Temperatures will remain a bit below normal again on Saturday...then
will rise into early next week and remain several degrees above
normal under fair skies. The Holiday weather looks good.
210430z...coast/valleys...areas of low clouds with bases around 2500
feet and tops to 3000 feet mean sea level have formed over the San Diego County
valleys and the foothills this evening. Currently...no taf sites are
impacted but higher terrain is obscured. Ksan and kcrq could be
impacted by broken-overcast ceilings at about 2500 feet mean sea level between 09z and
14z...but confidence in this outcome is low. Ksna and kont are
unlikely to be impacted by low ceilings and/or reduced visible through Sat.
Mtns/deserts...few clouds at or above 10000 feet with unrestricted visible
through Sat. Isolated northerly wind gusts to around 35 knots near mountain
peaks through Sat morning.
a long-period northwest swell arriving on Sunday will continue a high risk
of rip currents along the beaches through the middle of next week.
The swell will be 4-6 feet at 18-20 seconds in the outer waters and
could bring surf of 5-7 feet to the beaches by Monday.
Skywarn activation is not requested. However weather spotters are
encouraged to report rain and snow totals to their local National
Weather Service office.