Scientific Forecaster Discussion
Area forecast discussion
National Weather Service San Diego California
105 PM PST sun Nov 29 2015
Synopsis... the cold low pressure system that has dominated the
west throughout the Holiday weekend will drift eastward and be
replaced by a high pressure ridge through middle week. This will bring
gradual warming into Wednesday...although the nights will continue
to be quite cool with frost in some valleys and portions of the
deserts. Cooler late in the work week as another low pressure trough
swings through the region with gusty westerly winds. Then...warmer
and dry next weekend as high pressure rebuilds aloft.
Discussion...for extreme southwestern California including Orange...
San Diego...western Riverside and southwestern San Bernardino
Sunny skies and a drier airmass have helped push temperatures at
midday a few degrees higher than those observed yesterday. Weak surface
pressure gradients have kept winds light as well...making for a very
pleasant end to the Holiday weekend.
Despite the slight warming this afternoon...it will turn quite cool
again tonight with light winds and clear skies. Many spots in the
valleys and lower deserts could see temperatures close to the
freezing mark early Monday morning and again late Monday night and Tuesday
morning...so a frost advisory is in effect. See laxnpwsgx for
Daytime temperatures will gradually rise through midweek under
mostly sunny skies.
The cold low pressure system that has been hovering over the west
will drift east through midweek allowing heights/thickness to rise
across the region. This will mean warmer days under fair skies.
A weak trough will approach the West Coast on Thursday...turning surface
winds back onshore. Some marine clouds may return and the humidity
will be more comfortable...but no precipitation is expected. As the trough
swings east on Sat...warmer and dry weather will return for the
weekend. Offshore flow may briefly become strong and gusty below
the passes and canyons on Sat morning.
While the low pressure trough is expected to bring some rain to
northern portions of the state later this week...both the 12z runs
of the GFS/European model (ecmwf) models are in fair agreement that no significant
rain will fall across socal through the first ten days of December.
The development of a strong 590 dm ridge over the eastpac along 30n
latitude early next week blocks the westerlies far to the north...
setting all of cali up for a dry spell of weather.
292102z...unrestricted visible through Monday morning. Mostly sky clear...then
few-scattered clouds at or above 25000 feet mean sea level after 30/1200 UTC. Forecast
confidence is high.
102 PM...no hazardous marine conditions are expected
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
California...frost advisory from midnight tonight to 8 am PST Tuesday for
Coachella Valley-San Bernardino and Riverside County
valleys-the inland Empire-San Diego County deserts-San
Diego County valleys.