FXUS66 KLOX 181116
Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
316 AM PST Fri Jan 18 2019
Mostly cloudy skies will give way to partly cloudy skies by this
afternoon. A ridge of high pressure will build over the region on
today through Saturday bringing dry conditions, sunshine, and
warmer temperatures to the region. Increasing clouds are expected
by Sunday before an inside slider moves through the region Sunday
night into Monday bringing cooler temperatures. Prolonged offshore
winds expected through much of next week with no rain expected.
.SHORT TERM (TDY-SUN)...18/316 AM.
The final storm system has moved out of the area leaving behind a
rain soaked SoCal. Rainfall totals from the last three storms left
very impressive rainfall totals. Highest was over 10 inches at
Camp Hi Hill near Mount Wilson in the L.A. County Mtns and Rose
Valley at the northern edge of the Thomas Burn Area in the Ventura
County Mtns. Both Juncal Dam and San Marcos pass nearly reached 8
inches of total rainfall. To look at the complete Rainfall Totals
over the past several days covering the three storms check
For this morning, there is still plenty of low level moisture
lingering across much of the forecast area. A few light showers in
the foothills can't be ruled out, but overall the mostly cloudy
skies will turn to partly cloudy skies this afternoon. With plenty
of moisture soaked into the ground with light winds in most
coast/valleys this morning, areas of radiational fog has
developed across the Central Coast, Santa Ynez Valley and likely
across the SLO interior valleys with visibility one quarter mile
or less. Therefore a Dense Fog Advisory is in effect through 9 AM
this morning. There will be other coast/valley locations that will
experience some patchy dense fog as well with similar low
visibilities. A northerly surface gradient has developed allowing
for gusty NW-N winds across the western portion of the Santa
Barbara South Coast and Santa Ynez Range, as well as the
L.A./Ventura mountains (mainly the I-5 corridor) and Antelope
Valley with gusts remaining just below wind advisory thresholds.
An upper level ridge will build in from the south and persist
through Saturday before the ridge breaks down Sunday. a weak to
locally moderate Santa Ana will develop by Saturday morning. The
combination of the upper ridge overhead and offshore flow will
allow for significant warming across the coast and valleys. Highs
are expected to reach the mid 70s up 8 to 12 degrees from today.
Highs will be in the lower 60s across the Antelope Valley and
interior SLO Valleys.
Another upper trough will start to move into Nrn California
causing an increase of high clouds by Sunday morning and bringing
some cooling as offshore flow turns onshore by late Sunday
morning. High temps will lower a decent amount across the coast
and valleys while interior areas warm up, due to the onshore flow.
.LONG TERM (MON-THU)...18/308 AM.
The trough coming through late Sunday into Monday will begin to
dive into NV/AZ, as is typical of an inside slider track.
Northerly winds will increase across the mountains and SBA South
Coast, while clouds develop across the nrn slopes of the
mountains. Strong NW winds across the outer waters will cause a
Catalina Eddy to develop in the SoCal Bight Sunday evening which
should allow low clouds to develop across the L.A. Basin and
possibly the San Gabriel and San Fernando Valleys by early Monday
morning. Cold air will settle into Nevada and Great Basin by
Monday night and Tuesday, which will set up a relatively cool
Santa Ana. An amplified Eastern Pac ridge will set up off the west
coast driving any storm systems well north into the PAC NW or
Western Canada leaving Southern California dry through at least
next week. Prolonged offshore flow should persist through the week
as models are all in good agreement with similar solutions.
At 2350Z at KLAX...there was no marine inversion present.
Low to moderate confidence in the 00Z TAFs due to uncertainties
in the timing of changes in cig cats between LIFR/IFR/MVFR thru
this evening. However, there is hi confidence that these
conditions will gradually improve overnight into Friday. The front
causing the low visibilities/ceilings and precipitation was
exiting the region, but still a chance of residual showers for
some areas through this evening, mainly LA county.
KLAX...Low to moderate confidence in the 00Z TAF due to
uncertainties in the timing of changes in cig cats ranging between
LIFR and IFR through this evening. Conditions should improve to
MVFR overnight, but still a 20 percent chance of IFR conditions
lingering through the night.
KBUR...Low to moderate confidence in the 00Z TAF due to
uncertainties in the timing of changes in cig cats between IFR
and MVFR through this evening. MVFR conditions likely to continue
through the night, but still a 20 percent chance of IFR conditions
lingering through the night.
For the outer waters and zone 645, moderate to hi confidence in
the current forecast. Winds below Small Craft Advisory (SCA)
levels will continue with a large westerly swell resulting in a
Small Craft Advisory for Hazardous Seas (SCAHS) through Friday
night. Winds are forecast to increase to SCA levels at times Sun
and Mon, with a 40% chance of this occurring.
For the inner waters S of Point Conception, moderate to hi
confidence in the current forecast. A SCAHS is in effect through
Friday night. Winds are forecast to increase to SCA levels at
times Sun and Mon, with a 40% chance of this occurring.
Extremely large westerly swell moving into the coastal waters
tonight. Buoys off the Central Coast have already observed
20 to 23 foot swells, with periods of 17 to 19 seconds. This
has translated to max sets of 26 feet at Morry Bay Harbor.
For areas south of Point Conception, Buoy 053 (E SBA Channel Buoy)
swell has quickly increased to 13.8 feet with a period ranging
between 17 and 20 seconds.
High Surf Warnings in effect for potentially damaging surf across
west facing beaches, likely peaking tonight. The Central Coast
will continue to see surf of 20 to 26 feet, with west facing
beaches of LA/Ventura counties expected to see surf ranging
between 10 and 15 feet, with local sets up to 17 feet near
Ventura Harbor. Warning level surf is expected to persist into
With this very large surf and moderately high astronomical tides,
there will be a good chance of moderate coastal flooding and
beach erosion, especially around the Friday morning high tide.
A Coastal Flood Advisory is in effect as well. High astronomical
tides will continue through the weekend, but surf will begin to
subside Friday night.
In addition to coastal flooding and beach erosion issues, there
is a high potential for large breaking waves across the Morro Bay
and Ventura Harbor entrances through Friday.
Hazards associated with the very large and potentially damaging
surf will include strong and dangerous rip currents, minor to
moderate coastal flooding and significant beach erosion, as well
as waves washing over rock jetties. Conditions will be
potentially dangerous for even the most experienced swimmer.
CA...High Surf Warning in effect until 9 PM PST this evening for
zones 34-35-40-41-87. (See LAXCFWLOX).
Coastal Flood Advisory in effect until 9 PM PST this evening
for zones 34-35-40-41-87. (See LAXCFWLOX).
Dense Fog Advisory in effect until 9 AM PST this morning for
zones 34>37. (See LAXNPWLOX).
High Surf Advisory in effect until 9 PM PST this evening for
zone 39. (See LAXCFWLOX).
PZ...Small Craft Advisory for hazardous seas in effect until 9 AM
PST Saturday for zones 645-670-673-676. (See LAXMWWLOX).
Small Craft Advisory for hazardous seas in effect until 3 AM
PST Saturday for zones 650-655. (See LAXMWWLOX).
.HAZARD POTENTIAL OUTLOOK (SUN-THU).
Gusty offshore winds are possible Sunday and again Tuesday.
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