Area Forecast Discussion
Issued by NWS Los Angeles, CA

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FXUS66 KLOX 280606
AFDLOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
1106 PM PDT Mon Mar 27 2017

...Aviation discussion updated...

.SYNOPSIS...
Widespread strong west to north winds will affect the region
through Tuesday morning. High pressure will bring a warming trend
Tuesday and Wednesday. An upper trough of low pressure moving to
our north will bring cooling again for Thursday and Friday, with
warmer weather once again over the weekend.

&&

.SHORT TERM...(MON-THU)

A strong northerly pressure gradient is continuing to develop
across the area this evening as cold air punches in with a trough
of low pressure centered over Southwest Utah. Infrared imagery
shows some enhancement due to mountain wave activity across the
area. Several mountain and foothills locations are seeing gusty
northerly winds across the Los Angeles Basin this evening. Gusty
and potentially damaging winds in some locations will continue
through tonight and into Tuesday morning. A wind advisory for the
Central Coast will likely be allowed to expire at 9 pm PDT this
evening, but all other wind headlines will remain intact for now.

The trough of low pressure will continue to move east through
Tuesday while high pressure will build into the West Coast.
Northerly flow in the low-levels of the atmosphere this evening
gradually veer to northeast through Tuesday and into Wednesday
and set up a Santa Ana weather pattern. As a cold air mass settles
into the Great Basin behind the exiting trough, surface high
pressure will develop and provides the surface pressure pattern to
develop the Santa Ana. A warming and drying trend is forecast for
the area for Tuesday and Wednesday.

*** FROM PREVIOUS DISCUSSION ***

With the trough exiting east and good downslope flow taking place
with the Santa Ana winds most areas, especially west and south of
the mountains will see a sizable jump in temps Tuesday and again
Wednesday. Gradients are actually peaking Wednesday but upper
support wanes as the ridge axis moves overhead. So still some
gusty winds but mostly below advisory levels. Highs will warm up
well into the 80s in the valleys and some lower 90s for the
warmest areas by Wednesday. 70s to lower 80s for coastal zones.

Another trough that will eventually become our next inside slider
will hit nrn California early Thu. This will quickly reverse
gradients and cool temps several degrees Thu afternoon. Northern
areas may see a few clouds from it Thu afternoon but no precip.
May have to watch for some more Grapevine area showers Thu night
but at present models aren`t showing much moisture lingering
behind it so will keep forecast dry. But it will initiate another
round of gusty north to northwest winds Thu into Thu night in
many of the same areas as this morning and likely with similar
speeds if it follows the currently expected trajectory.

.LONG TERM...(FRI-MON)

A similar pattern shaping up for the end of the week as we`re
seeing in the first half of the week. Strong northwest flow Thu
into early Fri behind the trough with cooling temps, then
shifting to northeast Friday into Saturday for a quick warmup back
into the 80s for the valleys and 70s for coastal zones. Then
cooling again Sunday with the next trough which again appears to
be taking an inside track. Though here the GFS and ECMWF part ways
quite a bit with the EC showing a much faster and weaker trough
passage with virtually no gusty northwest flow behind it. So
somewhat lower confidence as we get later into the weekend but
given the pattern it seems prudent to hold onto the inside sliders
for the time being.

&&

.AVIATION...28/06Z.

At 03Z at KLAX... There was no notable inversion.

Overall... High confidence in the current TAFs. Moderate to
strong low-level wind shear and turbulence is possible at all
terminals through 18z. There is a thirty percent chance of LIFR
conditions at KPRB 13z-17z. Otherwise and elsewhere VFR conditions
will prevail.

KLAX... Moderate to high confidence in the current TAF. Moderate
to strong low-level wind shear and turbulence is possible through
18z. Northerly cross winds greater than 10 knots will linger
through at least 10z and as late as 13z. There is a ten percent
chance of northerly cross winds being greater than 20 knots 08z-
12z. There is a twenty percent chance of east winds to 15 knots
09z-16z. Otherwise VFR conditions will prevail.

KBUR... High confidence in the current TAF. Moderate to strong
low-level wind shear and turbulence is possible through 18z.
Otherwise VFR conditions will prevail.

&&

.MARINE...27/830 PM.

Gale warnings will continue across the outer waters tonight,
with the gales over the inner waters converted to small craft
advisories as winds will gradually relax overnight. Steep and
choppy waves will continue tonight into Tuesday. Another round
of gales will be possible across the outer waters on Thursday
and Friday.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...High Surf Advisory in effect until 2 PM PDT Wednesday for
      zones 34-35. (See LAXCFWLOX).
     Wind Advisory in effect until 3 AM PDT Tuesday for zone 39. (See LAXNPWLOX).
     Beach Hazards Statement in effect through Wednesday afternoon
      for zones 40-41-87. (See LAXCFWLOX).
     Wind Advisory in effect until 9 AM PDT Tuesday for zones
      41-87. (See LAXNPWLOX).
     Wind Advisory in effect until 2 PM PDT Tuesday for zones
      44>46-88-547. (See LAXNPWLOX).
     High Wind Warning in effect until 3 AM PDT Tuesday for zones
      52-59. (See LAXNPWLOX).
     High Wind Warning in effect until 9 AM PDT Tuesday for zones
      53-54. (See LAXNPWLOX).
     Wind Advisory in effect from 9 AM to 2 PM PDT Tuesday for
      zones 53-54. (See LAXNPWLOX).
PZ...Gale Warning in effect until 4 AM PDT Tuesday for zones
      670-673-676. (See LAXMWWLOX).

&&

.HAZARD POTENTIAL OUTLOOK...(THU-MON)
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...Hall/MW
AVIATION...Kj
MARINE...Gomberg
SYNOPSIS...DB/Sirard

weather.gov/losangeles


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