Area Forecast Discussion
Issued by NWS Los Angeles, CA

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000
FXUS66 KLOX 271204
AFDLOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
504 AM PDT Mon Mar 27 2017

...Aviation discussion updated...

.SYNOPSIS...

A mostly dry cold front will bring some rain showers and snow
showers to the mountains today, mainly to northern slopes. Behind
the front, widespread strong west to north winds will affect the
region later today through Tuesday morning. High pressure will
bring a warming trend Tuesday and Wednesday. An upper trough
moving to our north will bring cooling again for Thursday and
Friday, with warmer weather once again over the weekend.

&&

.SHORT TERM...(TDY-WED)

A frontal system was moving through the region early this morning.
There were some scattered showers across SLO and SBA Counties,
but those should be gone by daybreak as the frontal system has
become noticeably drier. The exception will be across interior
sections of SLO and SBA Counties, and the northern slopes of the
mountains of VTU and L.A. Counties, where upslope northwesterly
flow will help to squeeze out any moisture. This should keep a
fair amount of cloudiness and scattered showers for much of the
day. Snow levels will be between 5500 and 6000 feet, and local
accumulations of around an inch are possible across nrn VTU County
and nwrn L.A. County. Otherwise, skies will be partly cloudy
across the region today.

The main story will be the widespread strong west to north winds
which will overspread the region this morning and early this
afternoon and continue in some areas through mid morning Tuesday.
There is a fairly strong area of subsidence that will spread into
the region today, with fairly decent nwly winds at 850 mb and
700 mb. At this point, feel fairly confident that at least
marginal high wind warning level winds will affect the mtns of
L.A. and northeastern VTU County, near the I-5 corridor, and the
mtns of SBA County as well. Converted those watches to warnings,
from mid afternoon through Tue morning, except through late
tonight across SBA County. Also have gone with a high wind warning
for the Antelope Valley starting this afternoon, as 60 mph gusts
looks likely for western and foothills sections. Will have wind
advisories leading up to the warnings in all these areas.

Not as confident for high wind warning level winds in the Santa
Clarita Valley and the SBA south coast, so have left watches in
place for tonight (except into Tue morning across the Santa
Clarita Valley) to avoid locking in the next shift and affording
a look at the 12Z models. Elsewhere, wind advisories have been
issued for most other locations. At this point, feel winds will
stay just below advisory levels in the Santa Ynez Valley and the
interior valleys of SLO County. Advisories may have to be expanded
to the VTU County coast this afternoon, and to the San Gabriel
Valley, especially in the foothills if a mountain wave appears to
be setting up. Winds will decrease on the Central Coast this
evening, and in most other areas late tonight or Tue morning.

An upper ridge will amplify off the West Coast on Tue. Skies
should be mostly sunny. Rising heights and thickness values should
lead to several degrees of warming, especially west of the
mountains where low level flow will shift to a more northeasterly
direction. Max temps should reach 80 degrees in warmer coastal and
valley areas on Tue.

The ridge will continue to build Tue night and Wed and heights and
thicknesses will continue to rise. Low level flow will be
offshore, enough for some gusty ne winds across L.A. and VTU
Counties, but probably below advisory levels. Max temps will jump
again on Wed, possibly getting close to 90 degrees in some valley
areas.

.LONG TERM...(THU-SUN)

An upper level trough will move through the Pac NW and into the
Great Basin on Thu, then southeastward to the Four Corners area on
Fri. This should bring cooling to the region Thu and Fri, but it
appears that any rainfall will remain to the north and east of the
forecast area. An upper level ridge and offshore flow will bring
significant warming to the area on Saturday, with temps back up
into the 80s in the valleys and possible some coastal areas. Above
normal temps will likely continuing on Sunday.

&&

.AVIATION...27/12Z...

At 09Z at KLAX... There was no notable inversion.

Overall... Moderate confidence in the current TAFs. MVFR
conditions are possible at most locations overnight other than in
the Antelope Valley. Chances are greatest for terminals along the
Central Coast and along the Los Angeles County coast. There is a
slight chance of showers at San Luis Obispo County terminals
through 13z. All sites will become VFR by 16z-18z as winds become
strong and gusty through 03z. Antelope Valley sites remain VFR
throughout the forecast period.

KLAX... Moderate confidence in the current TAF. MVFR conditions
are likely 14z-17z otherwise VFR conditions will prevail. Winds
become strong and gusty 21z-03z. No east winds greater than seven
knots are expected.

KBUR... Moderate confidence in the current TAF. There is a less
than ten percent chance of MVFR conditions developing overnight.
Otherwise VFR conditions will prevail.

&&

.MARINE...27/230 AM...

For the Outer Waters... Northwest winds at Small Craft Advisory
(SCA) levels this morning will increase to Gale levels this
afternoon and continue through Tuesday morning. Winds will
diminish on Tuesday but will remain at SCA levels through
Wednesday. There is a good chance that winds will increase to Gale
levels again Thursday and Friday.

For the Inner Waters... Northwest winds at Small Craft Advisory
(SCA) levels this morning across the inner waters. For the waters
north of Point Sal there is high confidence in winds reaching
Gale levels this afternoon and evening then diminishing on
Tuesday. There is a good chance that winds will increase to SCA
levels Thursday and Friday.

For the Inner Waters south of Point Conception there is moderate
confidence in winds increasing to Gale levels this afternoon and
evening... primarily across western sections. Winds will diminish
on Tuesday then possibly increase to SCA levels again Thursday
and Friday.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory in effect from noon today to 9 PM PDT this
      evening for zones 34-35. (See LAXNPWLOX).
     Beach Hazards Statement in effect from noon PDT today through
      late tonight for zones 34-35. (See LAXCFWLOX).
     Wind Advisory in effect until 6 PM PDT this evening for zone
      39. (See LAXNPWLOX).
     High Wind Watch in effect from this evening through Tuesday
      morning for zones 39-88. (See LAXNPWLOX).
     Wind Advisory in effect from 3 PM this afternoon to 9 AM PDT
      Tuesday for zones 41-44>46-87-547. (See LAXNPWLOX).
     Wind Advisory in effect until 3 PM PDT this afternoon for
      zone 52. (See LAXNPWLOX).
     High Wind Warning in effect from 3 PM this afternoon to 3 AM
      PDT Tuesday for zones 52-59. (See LAXNPWLOX).
     Wind Advisory in effect from 9 AM this morning to 3 PM PDT
      this afternoon for zones 53-54-59. (See LAXNPWLOX).
     High Wind Warning in effect from 3 PM this afternoon to 9 AM
      PDT Tuesday for zones 53-54. (See LAXNPWLOX).
     Wind Advisory in effect from noon today to 6 PM PDT this
      evening for zone 88. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect until noon PDT today for zones
      645-650-655-670-673-676. (See LAXMWWLOX).
     Gale Warning in effect from noon today to 5 AM PDT Tuesday
      for zones 645-650-655. (See LAXMWWLOX).
     Gale Warning in effect from noon today to 11 AM PDT Tuesday
      for zones 670-673-676. (See LAXMWWLOX).

&&

.HAZARD POTENTIAL OUTLOOK...(WED-SUN)
Another round of strong and gusty northwest to north winds will
be possible Thu night in the mountains and along the Santa Barbara
County south coast, with travel being affected by the winds.

&&
$$

PUBLIC...DB
AVIATION...Kj
MARINE...Kj
SYNOPSIS...DB

weather.gov/losangeles



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