Scientific Forecaster Discussion
Area forecast discussion
National Weather Service San Diego California
359 am PDT Sat Oct 25 2014
a trough of low pressure will move inland this weekend with cooler
conditions...gusty onshore winds in the mountains and deserts...and
the marine layer returning. The marine layer may deepen enough
for patchy drizzle west of the mountains by Sunday morning. High
pressure will rebuild across the west with dry and warmer
conditions developing next week.
Discussion...for extreme southwestern California including Orange...
San Diego...western Riverside and southwestern San Bernardino
Very low stratus decks forming early this morning along the coast
but not yet expanding into the coastal valleys. Onshore gradients
have increased but are still not substantial. Believe the marine
layer penetration will continue to be rather weak this morning due
to light gradients. Later this afternoon upper level trough
passage will bring increasingly stronger onshore flow and a
deepening of the marine layer to Southern California. Temperatures today
will be nearly 10 degrees cooler than yesterday for the coast and
inland valleys...while the lower deserts see only minor cooling.
Secondary trough passage Sunday will bring yet another resurgence
of onshore flow allowing marine layer stratus to infiltrate the
inland valleys and continued cooler weather.
Winds will be diurnally gusty through Sunday evening with the
stronger wind gusts through the west facing passes and canyons to
the desert floor with peak gusts approaching 45 miles per hour in the most
Shortwave ridging ensues middle next week with warmer temperatures
likely...climbing back up to 5-10 degrees above normal. Light
offshore flow limited to the inland valleys will bring a little
stronger warming there as well as lower humidity.
Confidence is low in the pattern for late next week but the
ensembles are showing another rather strong eastern Pacific storm
system developing. Meanwhile the deterministic 00z ecm and 06z GFS
are now in a bit better agreement showing a split stream system
for late week into next weekend with the southern stream bringing
a deep upper trough into central and Southern California. Given
this unsettled pattern have brought climatology probability of precipitation for the Friday
night to Saturday time frame for now with plenty of room for
adjustments in the forecast over the next few days.
250930z...coast...patchy low clouds with some broken-overcast ceilings currently
along the immediate coast will increase in coverage through
15z...before becoming scattered between 17z and 19z. Bases are around 600
feet mean sea level but could lift to near 1000 feet mean sea level by 18z. Tops currently below
1000 feet mean sea level could also lift to near 1500 feet mean sea level. Expect areas of visible
3sm or less where clouds and terrain intersect. Low clouds will
likely return to the coastal areas between 03z and 06z
sun...spreading about 15 miles inland overnight with broken-overcast ceilings
1500-2000 feet mean sea level and tops to 2500 feet mean sea level.
Valleys/mountains/deserts...few/sct clouds at or above 6000 feet
mean sea level...otherwise mostly clear with unrestricted visible through Sat
200 am...patchy dense fog...with visibility of one mile or less...is
possible over the coastal waters early this morning. Northwest winds
with gusts near 20 knots will be possible over the outer coastal waters
late today into late Sunday. Otherwise...no hazardous marine weather
conditions are expected through Tuesday.
200 am...a northwest swell peaking at about 9 feet in the outer waters with a
14 second period...will create above normal surf of 3-5 feet...with
sets to 7 feet along exposed west-facing beaches on Sunday. Highest
sets will be near Huntington Beach and the beaches of southern San
Diego County. A beach hazard statement for elevated surf and a high
risk of rip currents GOES into effect Sunday morning.
Skywarn activation will not be needed today.
California...beach hazards statement from Sunday morning through Sunday
evening for the Orange County coastal areas...San Diego
County coastal areas.