Scientific Forecaster Discussion
fxus66 ksgx 232137
Area forecast discussion
National Weather Service San Diego California
137 PM PST Thu Feb 23 2017
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
Discussion...for extreme southwestern California including Orange...
San Diego...western Riverside and southwestern San Bernardino
At 1 PM PST, water vapor satellite imagery displayed two upper-
level lows off the Pacific NW, with northwest flow aloft over Southern
California. Northwest flow aloft will continue below normal high
temperatures, fair weather and a few high and low clouds at times
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 European model (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 probability of precipitation through the period, with likely probability of precipitation (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.
232104...local broken cigs 2000-5000 ft msl just north of the US/Mexico
border will continue to clear out through 2300 UTC. Otherwise,
primarily p6sm vis through Friday morning with scattered-broken clouds 3000-
5000 ft msl possible in the mountains, few-scattered clouds 3000-5000 ft
msl in the coast/valleys, and few clouds at or above 20000 ft msl elsewhere.
Locally strong winds and associated moderate uddfs/low level wind shear will
continue to gradually weaken through tonight over and east of the
northwest winds gusting 20-25 kt and combined seas of 7-11 ft will continue
over the coastal waters through this afternoon then diminish
tonight. 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.
at 12 PM, nearshore buoys reported swell heights at 7-9 ft with 12-
13 second periods. This elevated 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 activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
California...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.