Area Forecast Discussion
Issued by NWS San Diego, CA

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FXUS66 KSGX 202117

Area Forecast Discussion
National Weather Service San Diego CA
116 PM PST Tue Feb 20 2018

Sunny and cool today with more frost tonight. A cold north flow
pattern will continue this week with a chance for more scattered,
light showers at times beginning later on Wednesday and continuing
into Friday. Dry and a little warmer next weekend. More significant
precipitation is possible sometime next week, based on the latest
model guidance.



Skies were clear over all of SoCal this afternoon. Surface pressure
gradients to the deserts were near neutral this afternoon, and most
areas had light winds with a few gusts to around 20 MPH in the mtns.

Clear skies and light winds will set the stage for another chilly
night over SoCal. Frost Advisories have been posted for the inland
valleys where temps will dip into the upper 20s and 30s.

A longwave trough remains anchored over the West with a strong high
over the eastern portions of the Country. Disturbances moving
through the trough will keep our flow onshore, which will return
marine air, clouds and a chance for some light precip beginning
later on Wednesday and continuing through Friday. The various models
are handling the details differently which puts in question amounts
and timing. In general, though we are not expecting much in the way
of significant precip amounts overall. The snow levels will remain
rather low, so some light accumulations are likely at times in the
mts. No 12Z ECMWF was available today so the GFS was the prime
model used in the forecast beyond 3 days.

Stronger waves have been hinted at later in the forecast period
(next week) but once again, run to run differences in timing and
track make it difficult to gain much confidence with regard to
impact across SoCal. The storm systems all continue to come from the
north and have tracks that are largely land-locked. This would keep
precip amounts limited and snow levels rather low.

Daytime temps will be close to average by the weekend...but
temperatures overall will remain below average through the end of
the month at least. At this time though, the weekend looks dry and
warmer as we should be in between systems.


202040Z...Mostly clear skies with unrestricted visibility through
Wednesday morning.


No hazardous marine conditions are expected through early Thursday,
but hazardous winds and seas are likely again Thursday afternoon
through Friday.


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


CA...Frost Advisory from 10 PM this evening to 8 AM PST Wednesday for
     San Bernardino and Riverside County Valleys-The Inland
     Empire-San Diego County Valleys.




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