Scientific Forecaster Discussion
fxus66 ksgx 192046
Area forecast discussion
National Weather Service San Diego California
146 PM PDT Thu Sep 19 2019
breezy in the mountains and deserts through tonight, then
temperatures increase through the weekend with a shallow marine
layer. Upper-level low pressure will approach the area, creating
periods of offshore flow and lower temperatures.
Discussion...for extreme southwestern California including Orange...
San Diego...western Riverside and southwestern San Bernardino
At 1 PM, water vapor satellite showed an upper-level trough
moving across the region, which was creating a deep marine layer
across Southern California. Ensembles are in good agreement through the
short term, with the trough moving to the northeast Friday and
weak ridging over the weekend. This will create westerly wind
gusts of 30-40 mph across Desert Mountain slopes into adjacent
deserts through tonight, then the ridging will start to increase
high temperatures through Sunday. Weak offshore flow and the ridge
will create a more shallow marine layer by Saturday morning, with
low clouds being restricted mostly to the immediate coast.
Lower pressure aloft approaches the region early to mid-next week,
but ensembles are in big disagreement with the track of the
system. Mid-level moisture will start to approach our area from
the tropical systems to the south, but the chance of showers will
highly depend on the path of the low. All solutions currently have
Southern California dry, and considering how variable the model runs have
been, confidence in precipitation over our area is fairly low.
Offshore flow could develop across the foothills and far inland
areas Tuesday, but this all depends on the track of the system.
For now, confidence in periods of offshore flow next week remains
higher than the possibility of precipitation.
191945z...coast/valleys...VFR conditions for most areas, with
localized bkn025-030 ft msl, mainly in Orange County. Patchy low
clouds will redevelop after 04z Fri and make it 20-25 mi inland
overnight. Bases will be 1000-2000 ft mean sea level. Low clouds expected to
scatter out by 17z Fri.
Mountains/deserts...VFR conditions through Fri. Gusty west/northwest surface winds
from the mtn crests eastward into the deserts through tonight.
Expect gusts 30-40 kt in the mtns, and up to 25-30 kt in the
deserts. Low level wind shear and moderate uddfts will be possible over and east of the
no hazardous boating conditions are anticipated through Tuesday.
gusty westerly winds 30 to 40 mph will continue into this evening
in the mountains and desert slopes. Winds will be fairly light
through the weekend with humidity dropping into the teens and 20s
for the mountains and deserts. A low pressure system coming in
next week may also bring periods of offshore flow depending on its
track but confidence remains low at this time.
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.