Small Craft Advisory 6, NWS Los Angeles, CA

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
1006 PM PST Sat Jan 7 2017

.SYNOPSIS...
Rain and possible thunderstorms will continue this evening for
Santa Barbara and San Luis Obispo counties. Then late Sunday into
Monday a cold front will bring another round of rain to all areas.
Tuesday looks to be mostly dry, except for northern San Luis
Obispo County. High temperatures will be below normal for the
week. Another storm system is possible midweek.

&&

.UPDATE...

A very small short wave and its associated PVA brought a small but
intense cluster of Thunderstorms all the way from 120 miles west
of Point Conception through the SBA channel and the SBA south
coast and then into Ojai Santa paula area as well as the VTA mtns.
These thunderstorms were really putting on quite the light show as
well as a 20 minute downpour. There is a little break in the
action for the Central Coast but the rain will likely reform a
little before midnight. A weak ridge building in from the south
will keep the area south of Point Conception rain free and will
slowly shunt the rain north out of SBA county and most (or all) of
SLO county overnight.

The forecast was updated to reduce pops south of Point Conception
tonight.

Wind advisories are currently not doing too well but should pick
up soon and in fact might have to be xtnd into tomorrow.

Otherwise forecast is in good shape. 00Z NAM continues to show the
cold front with good rain moving through the SLO/SBA/VTA counties
tomorrow night and then ruining the L.A. Monday morning commute.
As mentioned before the rain with this system will be higher
intensity and shorter duration.

&&

.SHORT TERM...(SAT-TUE)

Current forecast thinking is on track through Monday. For today,
large plume of sub-tropical moisture will be drawn up by the upper
low in Gulf of Alaska bringing moderate to locally heavy rainfall
in San Luis Obispo and northern Santa Barbara counties. Light to
locally moderate rainfall in Ventura and Los Angeles counties is
possible, but the plume has shifted to the north where it will
remain this evening and overnight. At this time, northwest San
Luis Obispo county can expect 2-5 inches while the rest of San
Luis Obispo and Santa Barbara counties receive 0.50 to 1.00 inches
of rain. For Ventura and Los Angeles counties, amounts through
tonight will be less, generally between 0.25 and 0.50 inches.
There is a slight chance of thunderstorms north of Point
Conception in the forecast and already observing it 250 miles to
the west and approaching. Models also indicate some decent CAPE
values. There will also be some gusty southeast winds north of
Point Conception today/tonight, so have issued a wind advisory
for zones 34/35/37/51/52, and extending into 39.

On Sunday, best rain chances will be confined to San Luis Obispo
county. However by Sunday evening, models still indicate a potent
front will begin to sweep across the area, exiting Los Angeles
county Monday afternoon. This front will bring a 3-6 hour period
of moderate to heavy rainfall to the area. Depending on how things
develop with respect to rainfall intensity, there could be some
issues for the recent burn areas. Future shifts will need to watch
the potential rainfall rates as the situation develops. Rainfall
totals with this front still look to range between 0.50 and 1.50
inches with locally higher amounts in upslope areas (due to good
southerly flow).

Rainfall totals for Saturday through Monday should be 2-5" in SLO
County with 6+" in the Rocky Butte area, 1.5-3" in SBA County,
1-2.5" in Ventura Co, and 0.75-2" in LA County.

No significant winter weather issues are anticipated through
Sunday as snow levels will remain quite high, but as they drop
down to 7500 feet Monday night there may be minor accumulation in
the Ventura and LA County mountains.

Tuesday looks to bring a break in the rain pattern for most of the
area, the exception being in northern SLO County. The clouds will
remain and temperatures will be a few degrees below normal.

.LONG TERM...(WED-SAT)

Models in agreement with a possibility another system moving
through the area on Wednesday with the best rainfall chances
across SLO and SBA counties. NAEFS percentile for integrated
vapor transport for this event is "only" at 97.5 for this event as
opposed to the Sunday/Monday event which is maxed out.

Thursday and Friday will have only a slight chance of rain in
most places with cloudy skies and then there is a chance for
another system moving in on Saturday. Right now the EC is dry with
the GFS bringing rain as far south as northern SBA County. At a
week away, and with two other systems between now and then,
settling for a slight chance of rain and further monitoring
required.

&&

.AVIATION...

07/0555Z

At 0523Z, there was no marine layer or inversion at KLAX.

Good confidence in TAFs KSBA and south.

Low confidence in KPRB, KSBP and KSMX where light ocnl mdt rain
will continue in stops and starts overnight with frequent cig and
vis cat changes. There is a 40 percent chc of IFR cig/Vis and a 20
percent chc of LIFR cigs 07Z-14Z.

KLAX...Good confidence in VFR TAF. Good confidence that east winds
will remain under 8 kt through 16Z. There is a 30 percent chc of
east winds 10 to 12kt 17Z-21Z.

KBUR...Good confidence in VFR TAF.

&&

.MARINE...

07/900 PM

Lower to moderate confidence in current forecast...Gale Force
winds did not develop this afternoon and evening but models
continue to show stronger south winds on Sunday. This timing makes
sense as the winds will precede the next approaching cold front. Even
if gusts struggle to exceed 35 KT, confident in 30+ KT...which
should continue through most of Sunday. Due to the prolonged
nature of these winds, a steep, short period south swell will
build through the period, peaking Monday morning. Moderate
confidence in Small Craft Advisory (SCA) SE winds over the western
SBA Channel and south to San Nicolas Island. Thunderstorm chances
will continue off the Central Coast through around midnight
tonight.

&&

.BEACHES...

07/200 PM

A large south wind swell (6-10 feet) will peak around the 6 AM
Sunday morning high tide on the Central Coast. The astronomical
high tides forecast is 6.0 feet, but with the expected winds and
waves, the actual high tide will likely be near 6.5 feet. Similar
high tides and winds/waves in the past have produced coastal
flooding of beach roads and parking lots. The Pier and Grand
Avenue entrances to Oceano State Park is of particular
concern...as well as san simeon state park beach. Coastal
structures such as piers and buildings should NOT be impacted.

Minor coastal flooding on the Central Coast may occur again Monday
morning at high tide (646 AM). The high tide may reach 7.0 feet,
and while the winds will weaken, a southwest swell will push in.

Beach areas south of Point Conception will also have beach erosion
and possible minor coastal flooding concerns starting Monday.
High Tides should push to around 6.8 feet Monday morning, then
peak Wednesday and Thursday mornings to around 7.2 feet. Meanwhile
a west to southwest swell will build in, peaking on Thursday. If
any beach roads or parking lots will be impacted, Thursday will
be the day and a coastal flood advisory may be needed. Otherwise
impacts should stay confined to beach erosion and some
beach/harbor walkways (like Belmont Shores). Coastal structures
should NOT be impacted.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory in effect until 3 AM PST Sunday for zones
      34-35-37-39-51-52. (See LAXNPWLOX).
     Flash Flood Watch in effect through late Sunday night for
      zones 34-37. (See LAXFFALOX).
     Coastal Flood Advisory in effect from 3 AM to 9 AM PST Sunday
      for zones 34-35. (See LAXCFWLOX).
PZ...Gale Warning in effect until 3 PM PST Sunday for zones
      645-670-673. (See LAXMWWLOX).
     Small Craft Advisory in effect until 3 AM PST Sunday for
      zones 650-676. (See LAXMWWLOX).

&&

.HAZARD POTENTIAL OUTLOOK...(TUE-SAT)

There is a small potential for mud and debris flows near burn
areas Sunday night into Monday morning as moderate to heavy rain
moves through the area. There is also the potential for roadway
flooding as well as rock and mudslides, especially San Luis Obispo
County. Additional storms are expected later in the week but
timing and strength too uncertain to determine hazard potential.

&&

PUBLIC...JLD/Rorke
AVIATION...Rorke
MARINE...Smith
BEACHES...Kittell
SYNOPSIS...B

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