Scientific Forecaster Discussion
Area forecast discussion
National Weather Service San Diego California
127 PM PST Sat Nov 28 2015
cool days...cold nights and a slight chance of showers in some
areas this weekend with low pressure aloft. Dry and warmer Monday
through Wednesday with weak offshore flow and high pressure
building aloft. Precipitation possible Friday...along with below
normal highs and onshore flow...as a trough passes across the
Discussion...for extreme southwestern California including Orange...
San Diego...western Riverside and southwestern San Bernardino
At 1 PM PST...water vapor imagery displayed an upper-level low
over northern Utah...an associated trough stretching down to
central California...and a weak upper-level low off of the coast of Point
Conception. A few rain showers may develop over the coastal
waters through this afternoon.
The weak upper-level low to our northwest will quickly eject southeast over the
region early Sunday morning. Widespread precipitation is
unlikely...however a few snow showers are possible over the higher
peaks of the San Bernardino and Riverside County mountains...in
addition to an isolated shower over the coastal waters and Orange
County/the I.E. Lower temperatures are expected again tonight and
Monday morning with lower dewpoint temperatures and weak offshore
flow...though middle-level clouds moving over the region may keep
temperatures from plummeting tonight. A freeze warning has been issued
for tonight for portions of the I... deserts...and San
Diego County inland valleys and deserts. A freeze watch has also
been issued for the I... San Diego County inland valleys and
deserts for Sunday night.
Upper-level heights will slowly build Sunday through Wednesday
across the region. This...and weak easterly surface winds due to
offshore surface pressure gradients...will help high temperatures
rise 5 to 10 degree f above normal by Wednesday.
Heights will begin to fall and onshore flow will redevelop Thursday
as an upper-level trough approaches the region from the west. The
28/1200 UTC European model (ecmwf) and GFS generate light precipitation over SW California
on Friday as the trough passes through. For now...expect a small
chance of showers over and west of the mountains...breezy westerly
winds in the mountains and deserts...a return of coastal low
clouds/fog and high temperatures around 5 degree f below normal on Friday.
Warming is forecast for next weekend as heights quickly rise and
offshore flow develops with the passage of the trough.
282039z...unrestricted visible through Sunday morning...with few-scattered
clouds in the 5000-15000 feet mean sea level layer becoming broken after 29/1100
UTC. North to NE winds 10-20 knots gusting to 30 knots through passes/canyons
and into the coastal foothills will create moderate uddfs and areas of
low level wind shear in those areas. Some gusty NE winds may surface at kont this
afternoon and early evening...with low confidence.
1239 PM...isolated light showers are possible tonight and Sunday
morning over the coastal waters. No hazardous marine conditions are
expected through Thursday.
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
California...freeze watch from late Sunday night through Monday morning for
San Bernardino and Riverside County valleys-the inland
Empire-San Diego County deserts-San Diego County valleys.
Freeze warning from 1 am to 8 am PST Sunday for apple and
Lucerne valleys-San Bernardino and Riverside County valleys-
the inland Empire-San Diego County deserts-San Diego County