Area Forecast Discussion
Issued by NWS Los Angeles, CA

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FXUS66 KLOX 200616
AFDLOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
1016 PM PST Sun Feb 19 2017

...Aviation discussion updated...

.SYNOPSIS...

A series of storm systems will bring some rain and cool weather
this evening and persist through Wednesday. The highest rainfall
totals are expected to be north of Point Conception. Drier weather
is expected late in the week. Another storm is expected next
weekend.

&&

.SHORT TERM...(SUN-WED)

Radar and rain gauges indicated that light rain has overspread
SLO, SBA and VTU Counties this evening. There was also some light
rain being reported in Western Los Angeles County and in the
portions of the San Gabriel Valley and foothills. Rainfall rates
were very light, generally a few hundredths of an inch per hour
or lower, but the rain was steady. Some higher rainfall rates
were noted over southern and western Santa Barbara County, with a
couple of gauges reporting rates of one tenth on an inch or
greater per hour.

Satellite imagery shows a long fetch of moisture aimed at central
Ca, extending far off the coast. Satellite precipitable water
estimates show values as high as 1.6 inches off the Central Coast.
Expect rain to continue through the night, and pick up in
intensity some, especially across SLO and SBA Counties, with
light rain overspread all of Los Angeles Counties after midnight.
Rain may become locally heavy at times across SLO county,
especially in the higher terrain of northwestern SLO County,
where there will be favorable orographic enhancement of the
rainfall. Rain will be quite a bit lighter south of Pt
Conception, especially across L.A. County as this band of rain
weakens due to decreasing dynamics. Rain is expected to taper off
from in most areas by mid morning Monday.

Southeast to south winds have begin to increase across the
Central Coast and in the higher terrain of SLO and SBA Counties.
Wind Advisories look good for the Central Coast, as well as the
mountains of SLO/SBA Counties and SLO Interior Valleys where gusts
between 40 and 50 mph are expected late tonight into Monday
night.

*** from previous discussion ***

Another band of moisture will sag southward into the region from
northern and central CA late Mon or Mon night and linger into Tue.
This will be very similar to what occurs tonight and Mon morning,
with the heaviest rain and best moisture and dynamics remaining
across SLO and SBA Counties, Still, most areas should have
measurable rain Mon night into Tue, but amounts across VTU and
L.A. Counties are expected to be on the light side. Overall,
rainfall totals through Tue are expected to generally range
between 1 and 2 inches across SLO/SBA counties, with some local
amounts between 3 and 4 inches across the foothills of NW SLO
County. Across VTU County, expect one half to three quarters of an
inch of rain, with up to 1.5 inches in the western mountains.
Across L.A. County rainfall totals should generally range between
one quarter and one half inch. Snow levels will be rather high
through at least early Tue, so at this point, just expect a few
inches of snow at resort levels.

.LONG TERM...(THU-SUN)

A weak system will move through central California on Wednesday,
bringing a chance of rain to the entire region, with best chance
north of Point Conception. Thu and Fri look to be dry, but still
cool. Another storm system may bring rain to the region by late
Sat, and this system could be stronger, and bring more significant
rain to the entire region. However, there continues to be large
discrepancies between the GFS and ECMWF handling this system, so
confidence is low.

&&

.AVIATION...20/06Z.

At 05Z at KLAX... There was no notable inversion.

Overall... Moderate confidence in the current TAFs. The reduced
confidence is due to the variable CIGs and VSBYs expected with
the passing storm. Conditions will generally be MVFR through 18z-
20z then drop to IFR and occasional LIFR for a period of time
behind the storm before improving. There will be periods of rain
as well throughout the period and gusty southeast to south winds
across much of SLO and SBA Counties ahead of and with the frontal
passage.

KLAX... Moderate confidence in the current TAF. The reduced
confidence is due to the variable CIGs and VSBYs expected with the
passing storm. Conditions will generally be MVFR through 18z-20z
then drop to IFR and occasional LIFR through 06-08z before
improving. Winds are expected to turn east late tonight between 8
kt and 10 kt. There is a twenty five percent chance that east
winds will exceed 12 knots and a forty percent chance that they
will continue past 01z.

KBUR... Moderate confidence in the current TAF. The reduced
confidence is due to the variable CIGs and VSBYs expected with the
passing storm. Conditions will generally be MVFR through 18z-20z
then drop to IFR and occasional LIFR behind the storm.

&&

.MARINE...19/900 PM.

Southerly winds will increase tonight into Monday ahead of an
approaching cold front. Gale Watch posted for all water west to
northwest of Point Conception for Monday through Monday evening,
moderate to high confidence that widespread gusts to 35 knots will
occur. Until that time, SCA south to southeast winds expected
over the two northern outer zones and the northern inner waters.
SCA gusts may affect the western portion of the Santa Barbara
Channel Monday afternoon and evening, moderate confidence in gusts
to 25 knots during that time. Weakening winds expected on Tuesday
as the front passes south of the area. Winds will increase from
the northwest Tuesday night with SCA winds likely across most of
the waters by Wednesday and Thursday.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...High Surf Advisory in effect until 4 PM PST Tuesday for zones
      34-35. (See LAXCFWLOX).
     Wind Advisory in effect from 2 AM Monday to 6 AM PST Tuesday
      for zones 34-35-37-51-52. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect until 4 PM PST Monday for zone
      645. (See LAXMWWLOX).
     Gale Watch in effect from Monday afternoon through Monday
      evening for zone 645. (See LAXMWWLOX).
     Small Craft Advisory in effect until 10 AM PST Monday for
      zones 670-673. (See LAXMWWLOX).
     Gale Watch in effect from 10 AM PST Monday through Monday
      evening for zones 670-673. (See LAXMWWLOX).

&&

.HAZARD POTENTIAL OUTLOOK...(WED-SUN)
Light to moderate rain with gusty winds are expected Tuesday and
Wednesday which will create hazardous roadway conditions. More
rain is possible on Saturday and it will likely be windy.

&&
$$

PUBLIC...Gomberg/DB
AVIATION...Kj
MARINE...Smith
SYNOPSIS...Kaplan

weather.gov/losangeles



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