National Weather Service Forecast Discussion

Dicussion provided by the National Weather Service Forecast Office located in San Diego, California

000
FXUS66 KSGX 240431
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
831 PM PST Thu Feb 23 2017

.SYNOPSIS...
Fair and cool weather will continue through Saturday. A few
disturbances could generate rain, mountain snow and gusty winds
at times Sunday through early Tuesday. Dry and warmer weather with
possibly breezy offshore winds is expected for the middle of next
week.

&&

.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...

...Update...

Tranquil weather will continue tonight with chilly conditions.
This tranquil pattern will continue through Saturday.

We continue to monitor trough progressions for early next week.
Models have been struggling with position/timing, but the trend
over the past couple of days has been showing less of an impact
to Southern California. Current rainfall forecast is for 0.50-1.0
inches along the coastal mountain slopes and 0.10-0.50 inches for
the coast and valleys, less in the deserts. The GEFS mean shows
even less precip than the operational run. Still 3-4 days out so
we will continue to monitor this.

...Previous Discussion (Issued at 137 PM PST Thu Feb 23 2017)...

Northwest flow aloft will continue below normal high
temperatures, fair weather and a few high and low clouds at times
through Saturday.

The uncertainty for the Sunday through early Tuesday outlook
continues. Not many changes have occurred from the 23/0600Z to the
23/1200Z GFS run. In recent runs, the GFS has shown light precip
west of the mountains (mainly in San Diego County) Saturday
night/Sunday morning as an upper-level trough moves through to our
north, then more widespread moderate showers developing across
the region late Monday morning through early Monday night as an
upper-level trough moves over and taps into slightly greater
moisture. The 23/0000Z and the 23/1200Z ECMWF also disagree in
timing and precip amounts/placement for both systems compared to
the GFS. The one thing models do show is precip ending by late
Tuesday morning. For now, will maintain mostly slight chance to
chance POPS through the period, with likely POPS (greatest chance
for precip) Monday morning. Gusty southwesterly winds will be
possible in the mountains and deserts as each trough moves over.
Snow levels look to be around 5000-6000 ft Sunday, and lower to
4500-5500 ft by late Monday.

Highs should slowly rise to seasonal normals by next Thursday,
with periods of offshore flow for inland areas Wednesday and
Thursday. Strength of the offshore winds will depend on the track
of an upper-level low near the region and the strength of a
surface high over the Great Basin. A Wind Advisory could be needed
for the period.

&&

.AVIATION...
240400...Primarily P6SM vis through Friday morning with SCT-BKN
clouds 3000-5000 ft msl possible in the mountains, FEW-SCT clouds
3000-5000 ft msl in the coast/valleys, and FEW clouds AOA 20000
ft msl elsewhere.

Locally strong winds and associated moderate UDDFS/LLWS will
continue to gradually weaken through tonight over and east of the
mountains.

&&

.MARINE...
NW winds gusting around 20 kt and combined seas of 6-10 ft will
continue into the early morning hours Friday before improving.
These conditions will produce hazardous boating conditions, and a
Small Craft Advisory remains in effect through 2 AM Friday.

Another storm may bring a period of showers and gusty winds sometime
Sunday and Monday, but confidence in timing and expected impacts is
low at this time.

&&

.BEACHES...
At 7 pm, nearshore buoys reported swell heights down to near 4 ft
with an 11 second period. This west-northwest swell from 285-290
degrees will continue to generate surf of 4-7 ft and strong rip
currents along exposed west facing beaches through tonight. A High
Surf Advisory remains in effect through 2 AM Friday.

&&

.SKYWARN...
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...High Surf Advisory until 2 AM PST Friday for Orange County
     Coastal Areas-San Diego County Coastal Areas.

PZ...Small Craft Advisory until 2 AM PST Friday for Coastal Waters
     from San Mateo Point to the Mexican Border and out to 30 nm-
     Waters from San Mateo point to the Mexican Border Extending
     30 to 60 nm out including San Clemente Island.

&&

$$

PUBLIC...Gregoria
AVIATION/MARINE...Harrison

NWS SGX Office Area Forecast Discussion