Scientific Forecaster Discussion
fxus66 ksgx 241525
Area forecast discussion
National Weather Service San Diego California
825 am PDT Fri Mar 24 2017
fair and warmer today under high pressure aloft. Then, cooler as a
pair of weak, low pressure troughs move over the state Saturday and
again Monday. Onshore flow will increase, along with the marine
layer and associated clouds, and there may even be a few light
showers along and west of the mountains. Strong northwest winds are
likley over the coastal waters on Monday. Dry and warmer again into
the middle of next week as onshore flow subsides. Another storm
system is possible for Southern California late next week, with the
potential for strong winds and precipitation.
Discussion...for extreme southwestern California including Orange...
San Diego...western Riverside and southwestern San Bernardino
There were a few clouds over the coastal waters early this morning,
otherwise satellite imagery indicated it was clear. The 12z Miramar
sounding had a 3 degree c inversion based near 3600 feet mean sea level. Warming
of 5 to 10 degrees c was indicated in the 850 to 300 mb layer over
the past 24 hours, with just a few degrees of warming below to about
950 mbs. This should ensure a very stable atmospheric profile today
with few clouds and modest warming over yesterday. Onshore sfc
pressure gradients were weak and wind reports light. No forecast
changes this morning.
From previous outlook...
Short term (today through sunday)...
high pressure aloft will move inland across California today
bringing warmer and dry weather with high temperatures returning
to near average. For late tonight and Saturday...a trough of low
pressure will move inland through California. It will bring
stronger onshore flow with stronger and gusty west winds in the
mountains and deserts...and small chances for light precipitation
along and west of the mountains. High temperatures will cool to
around 5 degrees below average on Saturday. High pressure aloft
will once again move inland across California on Sunday with dry
weather and with high temperatures returning to near average.
Long term (monday through thursday)...
for Monday...yet another trough of low pressure moving inland
through California will bring small chances for light
precipitation...gusty west winds in the mountains an deserts...and
cooling to around 5 degrees below average.
Stronger high pressure aloft will bring dry weather and greater
warming for Tuesday and Wednesday. Less certain for the latter
part of the week is the placement of a closed low pressure system
that is expected to develop somewhere in the vicinity of the
southwest states. It is expected to bring some cooling and gusty
winds and possibly some precipitation depending on the placement
with Thursday/Friday the most likely time for greater impacts.
241449z...through 25/0600 UTC, primarily p6sm vis and few-scattered clouds
at or above 20000 ft msl. 25/0600-1500 UTC, broken-overcast clouds gradually forming
in the coast and valleys and then eventually reaching the coastal
slopes by 25/1500 UTC. Expect bases/tops to start out around 1000 ft
msl/2000 ft msl and then increase to 2000 ft msl/3000 ft msl by
25/1200 UTC and then up to 2000-2500 ft msl/4500 ft msl by 25/1500
UTC. Isolated showers possible over and west of the mountains by
25/1200 UTC producing local vis 5 sm. Expect mountain obscuration of
coastal slopes by 25/1500 UTC. Elsewhere, p6sm vis and scattered-broken
clouds at or above 15000 ft msl.
a trough moving through the region on Saturday will bring northwest
winds gusting to near 20 kt, choppy sea conditions, and possibly
some light showers. Although winds weaken early Sunday, northwest
winds are likely to strengthen again Sunday night through Monday,
with wind gusts likely reaching 25-30 kt on Monday for the inner and
outer waters. This, in addition to steep seas near 10 feet, will
result in hazardous conditions for small craft on Monday.
elevated swells from the west-northwest direction (around 285-290
degrees) will likely create above normal surf of 3-6 feet starting
Sunday and continuing through most of next week. An increased risk
of strong rip currents is likely as well.
Skywarn activation will not be needed today.