Area Forecast Discussion
Issued by NWS San Diego, CA
FXUS66 KSGX 261000 AAA
Area Forecast Discussion
National Weather Service San Diego CA
300 AM PDT Wed Apr 26 2017
Updated to add small craft advisory
Strong northwest flow aloft will bring strong winds to the
mountains and deserts this afternoon through tonight. Fair and
warm weather is forecast through the weekend with some offshore
flow and local northerly winds. High pressure will continue to
bring fair and warm weather next week.
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
Variable high clouds continue to stream across the sky from
northwest to southeast in our persistent northwest flow pattern.
Our search for coastal low clouds so far has come up empty. A
coastal eddy will spin up this morning to provide southerly
breezes along the coast, but the sea breeze this afternoon will
turn westerly. And that will be true again Thursday, bringing
areas of low clouds mainly to San Diego County. Brisk northwest
flow aloft will increase winds in the mountains and deserts this
afternoon through tonight. Top isolated gusts will exceed 60 mph,
but widespread gusts over 40 mph are expected. That could stir up
some dust in areas of the desert. The variable high clouds will
continue to stream across the sky through Friday. The surface
pressure gradient goes weakly offshore Friday morning even while
the eddy spins up. And then it happens again Saturday. But coastal
clouds will be few and far between. Some northerly offshore winds
will be felt mainly from Cajon Pass into Orange County mainly
Friday. A low pressure trough will amplify over the four corners
area and the northerly flow over our region will keep the offshore
flow going Saturday. Overall, we anticipate very few if any
clouds either high or low through the weekend. The offshore flow
Friday through Sunday will make it cooler in the mountains and
deserts, but warmer in the coastal basin. As onshore flow returns
next week, the coastal basin will cool while the mountains and
deserts warm. High pressure aloft amplifies along the west coast
for a lot of warm sunshine as we turn the calendar to May.
260900Z...Coast/Valleys...FEW-SCT clouds 1500-3500 ft MSL and SCT-
BKN clouds layers AOA 15000 ft MSL through this morning. BKN-OVC
clouds developing this evening after 06Z with CIGS 800-1500 ft MSL
through Thursday morning with patchy fog near the coast and where
low clouds intersect terrain.
Mountains/Deserts...SCT-BKN cloud layers AOA 15000 ft MSL and
unrestricted vis through Thursday morning. Strong SW-W winds
developing after 00Z Thursday with gusts 40-50 kts likely at times
through Thursday morning. Areas of blowing dust and sand likely in
Northwest winds and seas will increase Thursday through Friday, with
a return of Small Craft Advisory conditions. Winds and seas will
lower again over the coming weekend. A small craft advisory has been
issued beginning late this afternoon over the outer waters, expanding to
the near shore waters by late Thursday afternoon.
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
CA...Wind Advisory from 1 PM this afternoon to 3 AM PDT Thursday for
Apple and Lucerne Valleys-Coachella Valley-Riverside County
Mountains-San Bernardino County Mountains-San Diego County
Deserts-San Diego County Mountains-San Gorgonio Pass Near
PZ...Small Craft Advisory from 3 PM this afternoon to 5 AM PDT
Saturday for Waters from San Mateo point to the Mexican
Border Extending 30 to 60 nm out including San Clemente
Small Craft Advisory from 3 PM Thursday to 5 AM PDT Saturday for
Coastal Waters from San Mateo Point to the Mexican Border
and out to 30 nm.