Scientific Forecaster Discussion
Area forecast discussion
National Weather Service San Diego California
414 am PST sun Nov 29 2015
Synopsis... we will be in a quiet weather pattern through Wednesday
with weak offshore flow bringing mild days and relatively cold
nights. Low temperatures will fall near freezing in the inland
valleys and lower deserts where frost advisories are in effect.
On Friday a weak Pacific trough will bring clouds and a few light
Discussion...for extreme southwestern California including Orange...
San Diego...western Riverside and southwestern San Bernardino
The weather pattern is rather benign for our region...however the
temperature forecast has given US quite a fun night shift. Middle and
high cloud cover associated with a passing shortwave trough
continues to pass over Southern California. Cloud cover...as
discussed during previous forecast shifts...has put a wrench in
the expected cold temperatures for most areas early this morning.
At this time the coverage is beginning to dry out and thin so over the
next two hours we could see some decent radiational cooling...but
generally we're not expecting to reach the previous freeze
warning criterias for the valleys and deserts this morning.
Later today...the shortwave will move east of our region and allow
for full sunshine. Continued light offshore flow will bring a few
degrees of daytime warming over yesterday. Meanwhile the upper
level heights will begin to increase today...and by this time
tomorrow we expect 500 mb heights to be about 10 mb higher. This will
generally help to increase the surface temperatures...however with
less cloud cover...continued light offshore...and sheltered/valley
cold traps...we could see temperatures reach critical cold levels
by Monday morning. For this reason...we have issued a frost
advisory which will replace the previous freeze watch for the
inland Empire and the San Diego County valleys. Temperatures in
the lower deserts however...appear to generally remain above
critical levels for Monday morning.
A very weak trough will pass through late Monday and Monday
night...which should keep temperatures fairly stagnant...and
another critically cold night would be possible again for Monday
Late Tuesday through Thursday will feature more aggressive warming
aloft...bringing daytime temperatures to several degrees above
early December normals for Wednesday and Thursday...with
continued light offshore flow.
A Pacific trough will pass through our region Thursday night
through Friday...bringing a slight chance for precipitation...and
a renewed cooling trend to near normal to slightly below normal
temperatures by next weekend. The system continues to look quite
moisture starved...therefore no change to the probability of precipitation which are
barely above climatology for early December.
291145z...unrestricted visible with few to scattered at or above 10000 feet mean sea level through
18z Sunday...predominately sky clear thereafter through 18z Monday.
345 am...no hazardous marine conditions are expected through Thursday.
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 Monday for San
Bernardino and Riverside County valleys-the inland Empire-
San Diego County valleys.