Area Forecast Discussion
Issued by NWS San Diego, CA
FXUS66 KSGX 282043
Area Forecast Discussion
National Weather Service San Diego CA
200 PM PDT Fri Apr 28 2017
Offshore flow will strengthen through tonight and bring strong
northeast winds mainly through and below passes and canyons tonight
and Saturday morning. Otherwise, fair weather will prevail through
next week with temperatures averaging a little above normal. Some
coastal low clouds will return early next week.
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
After coastal low clouds cleared in San Diego County this morning,
skies were mostly sunny across the region. Local wind gusts, mostly
from the northeast, were above 25 MPH, mainly in the Inland Empire.
Early afternoon temperatures were mostly in the 70s west of the
mountains and 80s in the lower deserts.
Amplification of both the high pressure ridge over the East Pacific
and the trough over the western US will occur this afternoon and
tonight as a wave and associated strong jet stream dive south a
little inland from the west coast. We will be under a strong north-
northwest flow pattern through Saturday, and this will combine with
a surface high building over the Great Basin and a stable layer in
the 800-700 mb layer for the mountain wave to bring Santa Ana Winds
to some areas, especially below the Cajon Pass and in Orange County
where local gusts over 60 MPH are likely late tonight and Saturday
morning. Some moderately strong winds will occur in San Diego County
from the mountain crests west through the foothills, with local
gusts over 50 MPH there. Winds will decrease rapidly Saturday
afternoon as the support aloft decreases as the troughing in the
west shifts east and the north flow aloft weakens. It will be much
warmer west of the mountains, especially near the coast as some
temps could be above 90 within 10-15 miles of the coast, with
highest temps in Orange County. 850 MB temps will be several degrees
higher Sunday, but onshore flow will prevail by then, so mountains
and deserts will be warmer, but coastal areas will cool.
Next week, the high pressure ridge will slowly move from west to
east over California, with weak to moderate onshore flow at the
surface. Low clouds and fog will return to the coast probably Monday
night, possibly as early as Monday morning. Temperatures will
average a little above normal, especially in the Inland Empire,
mountains and deserts where the warm profile will be less affected
by the coastal marine layer. Some lower desert locations could reach
100 Wed/Thu. Some cooling could occur late in the week as the upper
high moves east and a weak Pacific trough approaches the west coast.
282030Z...Mostly clear skies and vfr conditions will continue
through Saturday. Strong northeast winds will develop in and west of
coastal foothills and through Orange County between 06-20Z Saturday.
Occasional up/downdrafts and llws are expected in some areas west of
the mountains and when/where strong low level winds don`t surface.
Northwest wind gusts of 25-30 kt will continue through early
Saturday. A short-period, choppy swell from 290 degrees peaking this
evening at 9-11 feet will diminish tonight and Saturday. A Small
Craft Advisory continues through early Saturday morning. Northwest
winds will increase again Saturday evening and may briefly pose a
hazard to small craft.
Large northwest swell will create surf of 3-6 feet, with local sets
to 7 feet, along with strong rip currents through this evening. Surf
will decrease tonight and Saturday.
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
CA...Wind Advisory from 10 PM this evening to 2 PM PDT Saturday for
Riverside County Mountains-San Diego County Deserts-San
Diego County Mountains-San Diego County Valleys-San
Gorgonio Pass Near Banning.
High Wind Warning from 10 PM this evening to 2 PM PDT Saturday
for Orange County Coastal Areas-Orange County Inland Areas-
San Bernardino County Mountains-San Bernardino and
Riverside County Valleys-The Inland Empire-Santa Ana
Mountains and Foothills.
PZ...Small Craft Advisory until 5 AM PDT Saturday for Coastal Waters
from San Mateo Point to the Mexican Border and out to 30 nm-
Waters from San Mateo point to the Mexican Border Extending
30 to 60 nm out including San Clemente Island.