Scientific Forecaster Discussion
Area forecast discussion
National Weather Service San Diego California
905 am PST Friday Dec 19 2014
a transitory ridge will bring a minor warming trend to Southern
California today...but will give way a weak disturbance passing by
to our north tonight. Although a few isolated showers might be
possible tonight and into early Saturday...expect primarily dry
conditions to prevail. High pressure will then build along the West
Coast...with dry and warmer conditions developing for early next
week. Offshore flow will develop as well these days.
However...cooler conditions will return for the latter part of the
week and the Holiday weekend.
Discussion...for extreme southwestern California including Orange...
San Diego...western Riverside and southwestern San Bernardino
Water vapor imagery shows a negatively tilted trough moving into the
Pacific northwest and northern California this morning...with a
transitory ridge shifting across Southern California. As a
result...dry conditions will prevail today...with relatively sunny
skies and slightly warmer conditions prevailing...following the
chilly start to this morning. However...high clouds will increase
again later today and into this evening...as the tail end of this
system approaches the region. At this time...the models are backing
off the potential for isolated showers for tonight into Saturday
morning...keeping the brunt of the moisture north of Point
Conception and over the bight. Will await the rest of the models
before making any changes to the forecast...as cannot completely
rule out that a stray shower will make it this far south.
High pressure pressure will rebuild along the West Coast for Sunday
and the first part of the work week...with dry and warmer conditions
developing. Offshore winds will develop on Sunday as well...with
the offshore surface pressure gradients increasing through Tuesday.
In fact...the models are hinting at some decent upper level support
by Tuesday...so will need to monitor for possible wind related
products...as a moderate Santa Ana may develop.
This ridge will flatten on Wednesday and Thursday...as another
trough of low pressure moves inland along the West Coast. At this
time...the GFS continues to be the most consistent of the
models...keeping this system to our north. Meanwhile...the European model (ecmwf)
continues to struggle with the strength of this trough...flip
flopping from run to run. The latest run once again introduces the
idea of rain for Southern California on Christmas. The 00z
Gem...splits the difference. However...given the track record of
the European model (ecmwf) over the recent days and past storms...will continue to
lean towards the drier solution of the GFS. Either way...expect
onshore flow to return...with cooler conditions developing once
191600z...sct/bkn high clouds through Sat morning. A weak
disturbance moving across the region tonight will create the
possibility of light isolated showers over and west of the
mountains. High clouds may inhibit the development of broken/overcast low
clouds west of the mountains tonight. Forecaster confidence in
widespread low cloud development tonight is low. Visible of 3-5 sm br is
possible tonight in low-lying valley areas.
800 am...no hazardous marine weather is expected through Tuesday.
800 am...a 6-7 feet/17 second period west-northwest swell arriving Saturday will
create elevated to high surf along westerly-facing beaches...mainly
in southern San Diego County and northern Orange County. Surf of 4
to 7 feet...with isolated sets to 8 feet...is expected Saturday
afternoon through Sunday. Morning high tides around 7
feet...combined with the high surf...may create minor coastal
flooding and tidal overflow. Strong rip currents will also be
possible throughout the weekend. Conditions will begin to improve on
Skywarn activation will not be needed today.