High Wind in California, January 27, 2017

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
321 AM PST Fri Jan 27 2017

Updated Marine Discussion

.SYNOPSIS...
High pressure and gusty offshore winds will bring fair skies and
above normal temperatures today into early next week. A low
will arrive on Wednesday for possible precipitation into Friday.

&&

.SHORT TERM...(TDY-SUN)

Overall, forecast in the short term looks on track with main
concern being Santa Ana winds.

Latest surface observations indicating winds are beginning to
increase across Ventura and Los Angeles counties with gusts
between 35 and 50 MPH across these areas. Current surface
gradients are showing a solid offshore trend and the LAX-DAG
gradient is forecast to peak around -5.0 mb this morning. Most
recent model data (with is limited due to some technology issues)
shows low level winds between 25 and 40 knots this morning. So
based on current trends and model forecast, moderate Santa Ana
winds will continue to develop today with warning level gusts
likely in the mountains as well as the Santa Clarita Valley.
Elsewhere across the coasts/valleys of Ventura and Los Angeles
counties, solid advisory-level winds can be expected. So current
slate of wind advisories and high wind warnings look good for
today.

For tonight and Saturday, models indicate stronger offshore
gradients, but slightly weaker upper level support. So, advisory
level winds are expected to continue across Ventura and Los
Angeles counties with a chance that the warning level gusts in the
mountains may continue. By Saturday night and Sunday, surface
gradients, as well as the upper level support, weaken which will
result in less widespread advisory-level winds (but some
advisories may be needed). For areas across San Luis Obispo and
Santa Barbara counties, offshore winds will be noticeably weaker
through Sunday, but still could be some locally gusty spots.

As for temperatures, the offshore flow will combine with a ridge
building overhead to bring a warming trend to all areas through
Sunday with most coastal and valley areas in the 70s by Saturday
and Sunday. As for overnight lows, wind sheltered areas will still
be pretty chilly the next couple of mornings with frost and freeze
issues continuing.

.LONG TERM...(MON-THU)

For the extended, Monday should be a very nice day as the upper
level high remains over the area (although a bit weaker) and
offshore flow continues. In fact, Monday should be the warmest day
through the forecast period. On Tuesday, the overall pattern
begins to change as a trough develops off the West Coast. With the
developing trough and gradients turning onshore, Tuesday will be
several degrees cooler for all areas. On Wednesday and Thursday,
the upper level trough will move inland, bringing the potential
for more rainfall to the area. At this time, most of the energy
remains north of the area, so the associated surface cold front
should weaken as it moves south and east. So, best chances of rain
on Wednesday will be across San Luis Obispo and Santa Barbara
counties with showery conditions continuing Wednesday night and
Thursday. For Ventura and Los Angeles counties, chances of
precipitation will be a bit lower, but still very much worth
watching. Rainfall amounts for Wednesday and Thursday should be on
the light side (and nothing anywhere near what the area received
the last few days).

&&

.AVIATION...27/0628Z.

At 06Z, there was no marine layer or marine inversion at KLAX.

Moderate confidence in timing and strength of offshore winds for
TAF sites most impacted by Santa Ana winds. Switch to onshore
winds at coastal TAF sites may differ from +/- 2 hours from TAF.
VFR conditions are expected throughout the period, except for a
20 percent chance of VLIFR to LIFR conditions at KPRB between 12Z
and 17Z. Periods of moderate to locally strong wind shear and
turbulence will likely develop through 12Z at all terminals south
of KSBA and linger possibly as late as 22Z, especially for KBUR
and KSMO.

KLAX...VFR conditions are expected throughout the period. There is a
10 percent chance of east winds of 10 knots between 12Z and 16Z.
Switch to onshore winds possibly anytime between 19Z and 22Z.
Periods of moderate to occasionally strong turbulence and wind
shear are possible 10Z to 22Z.

KBUR...VFR conditions are expected throughout the period. Periods
of moderate to strong turbulence and wind shear are likely at
times 10Z to 18Z, possibly lingering through 22Z.

&&

.MARINE...27/0320 AM.

A Small Craft Advisory remains in effect due to hazardous seas
across the Outer Waters and the northern nearshore waters. There
is a 40 percent chance that winds and seas could become hazardous
for the waters south and west of the Channel Islands out to 60 nm
offshore. Otherwise, winds and seas are expected to fall below
advisory levels late this morning, with no small craft conditions
expected for these areas through early next week.

A small craft advisory continues for gusty northeast winds,
especially south of Ventura to Pacific Palisades and through the
San Pedro Channel. Gusty northeast winds could bring hazardous
boating conditions to east facing harbors such as Avalon Harbor on
Santa Catalina Island and Smugglers Cove on Santa Cruz Island.
Winds should diminish some Friday night and into Saturday. Weaker
offshore winds are expected to peak overnight into the morning
hours again Saturday, Sunday and possibly Monday with a 30 percent
chance of Small Craft Advisory winds during these times.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...High Surf Advisory in effect until 10 PM PST this evening for
      zones 34-35. (See LAXCFWLOX).
     Frost Advisory in effect until 9 AM PST this morning for
      zones 35-39. (See LAXNPWLOX).
     High Surf Advisory in effect until 5 PM PST this afternoon
      for zones 40-41-87. (See LAXCFWLOX).
     Wind Advisory in effect until 6 PM PST Saturday for zones
      40-41-44-45-547. (See LAXNPWLOX).
     Freeze Warning in effect until 9 AM PST this morning for zone
      44. (See LAXNPWLOX).
     High Wind Warning in effect until 10 PM PST this evening for
      zones 46-53-54-88. (See LAXNPWLOX).
PZ...Small Craft Advisory for hazardous seas in effect until 9 AM
      PST this morning for zones 645-670-673-676. (See LAXMWWLOX).
     Small Craft Advisory in effect until 3 PM PST this afternoon
      for zones 650-655. (See LAXMWWLOX).

&&

.HAZARD POTENTIAL OUTLOOK...(SUN-THU)
Gusty northeast winds will continue over Los Angeles and Ventura
Counties on Sunday. A weak storm system could impact the region
Wednesday or Thursday.

&&

PUBLIC...RAT
AVIATION...Munroe
MARINE...Munroe
SYNOPSIS...STU

weather.gov/losangeles