Area Forecast Discussion
Issued by NWS Los Angeles, CA
FXUS66 KLOX 290629
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
1129 PM PDT Fri Apr 28 2017
Gusty offshore winds with support for continued warming west of
the mountains can be expected through Saturday. A transition to
onshore flow will bring cooler conditions to the coast and some
valleys with warming across interior areas as high pressure builds
overhead through at least early next week.
Mostly clear skies covered the forecast area early this evening and
will continue overnight as offshore flow persists. Gusty nw to n
winds prevailed over the Central Coast, portions of the SBA County
mtns and s coast, L.A./VTU County mtns, Antelope Vly, and several of
the vlys of L.A./VTU Counties. Winds are expected to diminish along
the Central Coast and Antelope Vly thru late this evening, but
increase and persist in many of the vly and mtn areas of L.A./VTU
Counties overnight into Sat, where Wind Advisories are in effect for
many areas. With fairly widespread 850 mb winds 50 to 55 kt later
tonight, will upgrade Wind Advisory to High Wind Warning for the
L.A. County mtns overnight into Sat morning with gusts up to 65 mph.
It will also be close to warning thresholds in the Santa Monica Mtns
with 950 mb winds 40 to 45 kt later tonight. The adjacent vlys will
have gusts 40 to 50 mph at times overnight thru Sat morning. Please
see the latest Non-Precipitation Weather Message for further details
on the gusty winds.
Srn CA will be sandwiched between an upper high over the e Pac and
an upper trof over the Great Basin tonight through Sat, with a
strong nw to n flow aloft. The upper trof will move e Sat night and
Sun, with the upper ridge gradually expanding into CA Sun thru Mon.
Mostly clear skies will prevail across the forecast area Sat thru
Mon thanks to the upper ridging and offshore flow over the region,
altho the offshore flow will be much weaker night and morning hours
Sat night into Mon morning.
Temps are forecast to warm to 5 to 15 deg or more above normal for
may areas Sat before cooling slightly to 5 to 12 deg above normal
overall for Sun and Mon. Highs in the warmest vlys and inland
coastal areas should reach the mid 80s to lower 90s Sat, and 80s to
around 90 on Sun and Mon.
***FROM PREVIOUS DISCUSSION***
Models agree that a ridge will build over the area through
Thursday while at the same time a weak to moderate onshore flow
continues at the surface. So inland areas will warm up,
particularly far interior areas, while areas closer to the coast
will likely flat line on temps after Monday (ie. still about 5
degrees above norms) as the onshore breeze keeps temps provides a
natural air conditioner. There`s some indication on the GFS that
by Wed or Thu a little offshore push could develop that would lead
to a bigger warmup for coast/valleys but it`s too early to bite
on that. Will see if that trend continues with future models.
At 0540Z at KLAX, there was no marine layer or inversion.
Very high confidence in CAVU conditions for at least the next 30
hours. Decent confidence in the winds forecast. Transition times
for wind changes may be off by an hour. There is a 30 percent chc
that the easterly winds will not develop at KLAX and KLGB.
KLAX...Very high confidence in CAVU conditions for at least the
next 30 hours. Fair confidence in wind forecast. There is a 30
percent chc that the north winds will persist through 12Z. There
is also a 30 percent chc the the easterly winds will not develop.
KBUR...Very high confidence in CAVU conditions for at least the
next 24 hours. Wind shift transition times may be off by an hour.
There will be lgt-ocnl mdt turbc in the area through 15Z.
Low confidence in Gale conditions across the Outer Waters tonight
with a 40 percent chance they do not occur. High confidence in at
least small craft conditions continuing across all waters
tonight. There is a 20 percent chance of SCA conditions returning
Saturday evening. Small craft conditions will likely continue at
times across the Outer Waters through Tuesday.
Due to strong winds throughout the waters, seas will be large and
very choppy in all areas through late tonight, creating hazardous
CA...Wind Advisory in effect until 3 AM PDT Saturday for zones
39-52. (See LAXNPWLOX).
Wind Advisory in effect until 2 PM PDT Saturday for zones
44>46-53-88-547. (See LAXNPWLOX).
High Wind Warning in effect until 9 AM PDT Saturday for zone
54. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect until 3 AM PDT Saturday for
zones 645-650. (See LAXMWWLOX).
Small Craft Advisory in effect until 3 PM PDT Saturday for
zone 655. (See LAXMWWLOX).
Gale Warning in effect until 3 AM PDT Saturday for zones
670-673-676. (See LAXMWWLOX).
.HAZARD POTENTIAL OUTLOOK...(MON-FRI)
No significant hazards expected.