Area Forecast Discussion
Issued by NWS San Diego, CA

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000
FXUS66 KSGX 211709
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
909 AM PST Wed Feb 21 2018

.SYNOPSIS...
After a cold morning, clouds will increase today and lead to a few
light showers from the coast to the mountains, but most likely in
San Diego County. This small chance of light showers will
continue through early Friday morning. Brisk winds are also likely
Thursday, especially in the mountains and deserts. A fair and
warmer weekend is expected before low pressure returns next week
for more cold weather and another chance of showers.

&&

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

A weak shortwave embedded in the mean cyclonic flow aloft has
brought cloudy skies this morning, along with some isolated light
showers. Most locations have reported no measurable precip thus
far. The cloud cover has limited the radiation cooling overnight
so that most locations were a few degrees warmer than at the same
time yesterday.

The long wave pattern over the globe has the western U.S.
dominated by a longwave trough. Shortwaves will rotate through
Southern California within this longwave trough for at least the
coming week. Today we get the first wave bringing us the clouds
and light showers today. Expect light showers anywhere in the
coastal basin and into the coastal slopes of the mountains through this
afternoon. The second wave moves in from the north on Thursday,
bringing a similar precip scenario, but this wave has more dynamic
energy, so precip chances continue into early Friday along with
stronger west winds in the mtns and deserts. Both these waves
favor San Diego County for the best chances of measurable precip.
The snow level will be low, around 3500 to 4000 feet, but
accumulations will be very light. The winds will be quite strong
in the mountains and deserts Thursday and Thursday night. The
winds weaken and turn offshore Friday morning to flush out the
clouds and precip. Weak offshore flow will continue through the
weekend and it looks pretty sunny, although with cool days and
cold nights (not as cold as our last two nights, however). Next
week, a third wave reaches the West Coast with more moisture
than the previous two. This has some promise for significant
precipitation, but the timing and strength discrepancies between
models keep confidence low. Either Monday or Tuesday we`re
forecasting winds and precipitation.

&&

.AVIATION...
211645Z...Increasing clouds over/west of the mountains with bases
2500-3500 ft MSL and tops varying between 5000-8000 ft MSL. Portions
of the coastal mountain slopes obscured in clouds/fog/precip through
tonight. ISO-SCT light showers through tonight.

&&

.MARINE...
No hazardous marine conditions are expected through Thursday
morning, but hazardous winds and seas are likely again Thursday
afternoon through Friday. Winds and seas will diminish through the
weekend.

&&

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

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...NONE.

&&

$$

PUBLIC/AVIATION/MARINE...PG


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