Area Forecast Discussion
Issued by NWS Los Angeles, CA

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506
FXUS66 KLOX 250320
AFDLOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
820 PM PDT Fri Mar 24 2017

.SYNOPSIS...
A weakening cold front will bring light rain to the area tonight
into early Saturday morning. Monday a dry inside slider will
result in gusty northerly winds and cooler air. Weak ridging aloft
and northerly winds at the surface will bring warm and dry
conditions for the middle of next week.

&&

.SHORT TERM...(Tonight-MON)

Weak cold front bringing light rain to portions of SLO and western
SBA counties this evening. So far, totals have been light with
amounts less than 0.05 inches in SLO County. All in all, much
of SLO/SBA counties will likely see less than 0.25 inches with
this system, however isolated totals up to around 0.50 inches. As
the front moves southeast later tonight and Saturday morning,
look for a chance of light showers with amounts generally under
0.10 inches. Snow levels expected to lower to 6500 to 7000 feet by
Saturday morning, where an inch or two of snow will be possible.
The front is expected to shift well east by Saturday afternoon
with cool and breezy conditions across the area. Some residual
moisture will linger on Saturday night across the north facing
mountain slopes where a slight chance of showers will persist.

***From previous discussion ***

Weak upper level ridging will move over srn CA Sat night into Sun,
altho by later Sun another e Pac upper trof will approach the
Central Coast, with increasing clouds and a slight chance of rain
developing over nwrn SLO County by late in the day. Otherwise,
partly cloudy skies can be expected for the second half of the
weekend.

The upper trof and dissipating surface cold front will move into CA
Sun night then move slowly e on Mon, with a broad nw flow aloft over
the forecast area. This system will bring a slight chance of showers
to SLO County and the n mtn slopes Sun night, with some rain and
snow showers lingering mainly on the n slopes on Mon. Precip amounts
from this system will be light and generally less than a tenth of an
inch where pcpn occurs.

Gusty nw to n winds will be possible over the SBA County mtns and s
coast Sat evening, as well as along the n mtn slopes into the I-5
corridor. Winds may approach advisory levels at times. Even stronger
winds are expected across the mtns and SBA County s coast Mon
afternoon into Mon night as strong northerly pressure gradients
develop. There should be gusty nw winds along coastal areas as well
Mon afternoon, especially the Central Coast. Wind advisories will be
possible for several of these areas Mon afternoon and Mon night.

Temps are forecast to turn cooler Sat before warming some on Sun.
Highs will be several degrees below normal on Sat, then be near
normal to slightly below normal overall for Sun and Mon. Highs in
the warmest vlys and inland coastal areas will be in the mid to
upper 60s Sat, and upper 60s to lower 70s Sun and Mon.

.LONG TERM...(TUE-FRI)

The EC/GFS are in generally good agreement with the synoptic scale
features Tue thru Fri. The upper trof that moved thru the area Mon
will slide e and thru the Great Basin to the srn Rockies on Tue,
while at the same time an upper ridge builds into the e Pac. Upper
ridging will persist over srn CA on Wed, then weaken Thu as an upper
trof moves into the Pac nw. This upper trof is forecast to dive se
into the inter-mountain west Thu night and Fri, with a broad
northerly flow over srn CA.

Dry weather with mostly clear skies will prevail across the region
Tue thru Fri. The bigger weather story will be strong and gusty
winds at times, especially Tue thru Tue night and again Thu night
into Fri, as a strong northerly gradient persists at times. This
will bring gusty northerly winds to much of the area, with gusty ne
winds possible over SLO/SBA Counties night and morning hours. The
strongest winds should be over higher terrain especially along the I-
5 corridor and below and thru passes and canyons of SLO/SBA
Counties. Gusty winds will also affect the Antelope Vly. Winds may
approach warning thresholds at times in some areas, but for now it
appears strong advisory level gusts should prevail in the windiest
locations.

Temps are expected to warm up considerably during the extended
period, with highs several degrees above normal for may areas on
Tue, then peak at 5 to 10 deg above normal way from the immediate
coast Wed. Temps should turn slightly cooler Thu and Fri but remain
near normal to several degrees above normal for much of the region.
Highs in the warmest vlys and inland coastal areas should reach the
mid 70s to around 80 on Tue, low to mid 80s Wed, and mid 70s to
around 80 Thu and Fri.

&&

.AVIATION...25/0130Z.

At 00Z, there was a weak marine layer at 900 feet and an
inversion at 4000 feet with a temperature of 12 degrees Celsius at
the top of the inversion.

Moderate confidence in VFR conditions everywhere through at least
03Z today. Weak cold front will move down the coast tonight. 90
percent chance of -RA at KPRB KSBP KSMX...60 percent chance at
KSBA...and 30 percent chance elsewhere. MVFR CIGS are likely over
most places with the timing of the front...with a 30 percent
chance of brief IFR cats at KPRB KSBP. 30 percent chance of MVFR
CIGS forming as early as 05Z ahead the front anywhere over Los
Angeles and Ventura Counties. Widespread gusty west to northwest
winds are likely Saturday afternoon with mostly CIG-free skies.

KLAX...High confidence in VFR conditions through 05Z today. 30
percent chance of MVFR CIGS 06-12Z...60 percent chance 12-18Z and
a 30 percent chance of -RA. No significant east winds expected
over next 24-hour period. Gusty west winds likely Saturday
afternoon.

KBUR...High confidence in VFR conditions through 03Z today. 10
percent chance of MVFR CIGS 06-12Z...60 percent chance 12-18Z and
a 30 percent chance of -RA.

&&

.MARINE...24/800 PM.

Low-end Small Craft Advisory (SCA) gusts up to 25 knots will
affect the waters south of Point Conception through around midnight,
and will begin to weaken during the early morning hours...strongest
over the western portions of the inner waters. A weak front will
move down the coast tonight, which will help to temporarily weaken
the winds later tonight into Saturday, but widespread gusty NW
winds will form by Saturday afternoon with most of the area
needing a SCA. There will be a 30 percent of localized Gale
conditions for the outer waters from Point Conception to the
Channel Islands. The winds will weaken again nearshore Saturday
night through Sunday morning, but will increase again by Sunday
evening.

In general, the northwest winds will strengthen each day through
Monday evening, when they will peak with widespread gales
possible. There will be a 70 percent chance of gales from the
Central Coast to San Nicolas Island, and a 40 percent chance of
gales over the Inner Waters south of Point Conception. Due to the
gusty, persistent winds...short period (6-8 second) waves will also
likely persist through early next week peaking Monday night
through Wednesday.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...Small Craft Advisory in effect from 3 PM Saturday to 3 AM PDT
      Sunday for zones 645-670-673. (See LAXMWWLOX).
     Small Craft Advisory in effect until 3 AM PDT Saturday for
      zones 650-655-676. (See LAXMWWLOX).

&&

.HAZARD POTENTIAL OUTLOOK...(MON-FRI)
A weak weather system will bring some showers and mountain snow
showers to SLO County and the north mountain slopes on Monday.

Gusty northwest to northeast winds will affect the area at times
Monday through Friday. The winds should cause some travel issues
at times during the period. Winds may be strong enough in some
areas for small trees or tree branches to be knocked down.

&&

$$

PUBLIC...Gomberg/Sirard
AVIATION...Kaplan
MARINE...Smith
SYNOPSIS...Laber

weather.gov/losangeles



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