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Area Forecast Discussion (AFD)

Issued by Los Angeles, CA (LOX)

FXUS66 KLOX 161015

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA 
315 AM PDT Thu Aug 16 2018

.SYNOPSIS...15/930 PM.

Possible storms on Thursday for Ventura and eastern Los Angeles 
mountains, and deserts. The high will return Friday and persist 
through next week for above normal temperatures and fair skies, 
except for an overnight coastal marine layer.


.SHORT TERM (TDY-SAT)...16/310 AM.

CA is between a weak upper trof to the NW and a large upper high
centered over TX. Gradients are weakly onshore and similar to last
night. The marine layer has increased to 1600 feet and a weak eddy
has brought low clouds as far north as Oxnard. The Central coast
is already enveloped by low clouds and by dawn almost all of the
coastal areas will be covered with low clouds. The depth of the
marine layer will allow it to move into the San Gabriel and San
Fernando Vlys. The gradients are weak and this will allow total
clearing by late morning. Hgts are 589 DM and max temps today will
come in within a degree or two of normal. The biggest question
today will be the afternoon convection. Right now a little outflow
is moving across the deserts towards LA county but Satellite shows
it weakening and will not much affect LA county. It looks like 
there is a good chc of a tstm or two developing over the 
Wrightwood area and the western portions of the Antelope Vly there
is a lesser chc of a TSTM over the rest of the LA mtns and the 
higher peaks of the VTA mtns. Right now the bulk of the moisture
is forecast to remain to the east and south of the area but heavy
rains are still possible and any TSTM that forms will need close

Not much change tonight. Skies may be partly cloudy due to monsoon
debris clouds. The eddy looks weaker and it appears that the SBA 
south coast will remain clear although this is not a sure thing.

The trof asserts itself over the state on Friday at least as far
as the flow pattern is concerned. The upper flow will turn more
westerly and this will eliminate the convective threat. Despite 
the trof hgts actually rise a little and most areas will be a 
degree or two warmer than today.

On Saturday an upper ridge bulges into the state from the SW and
by the afternoon it develops into an upper high over the state.
Hgts increase to 595 DM. The marine layer and the gradients look
similar and max temps will bump up by a degree over most area and
will be a degree or two above normal.

.LONG TERM (SUN-WED)...16/315 AM.

A pretty quiescent xtnd forecast. Both the EC and the GFS agree
that a trof will move in over the PAC NW and the upper high will
move to the east and set up over western NM. Hgts will fall to 590
DM on Sunday and then will change little through mid week.

Temps will fall to normal on Sunday and then will change little
over the next three days. The marine layer stratus will be
confined to the coast with the exception of the SBA south coast.

The convective threat looks minimal through the forecast period
but it looks like it could become more active at the end of the



At 0600Z at KLAX, the marine layer was 1500 feet deep. The top of
the inversion was around 2400 feet with a temperature of about 22
degrees Celsius.

Moderate confidence in coastal terminals across LA county and the
Central Coast where timing may be off by 90 min and cigs may be
one cat lower than fcst. Low Confidence in KSBA, KOXR and KCMA
TAFs where timing could be off by 2 hours and also there is a 40 
percent chc of no cigs.

At inland terminals, VFR conditions are expected throughout the
period, except for a slight chance of LIFR to IFR conditions
between 11Z and 16Z.

KLAX...Moderate confidence in TAF. Cigs may arrive as late as 09Z.
There is a 30 percent chc of IFR cigs. Good confidence that there
will be no east wind component greater than 5 KT.

KBUR...Good confidence in TAF with a 10 percent chance of LIFR 
conditions between 11Z and 15Z.


.MARINE...16/234 AM.

For the Outer Waters... There is a thirty five percent chance of
Small Craft Advisory (SCA) conditions across the northern outer 
waters late this afternoon through late evening. There is also a 
forty percent chance of SCA conditions across the entire outer 
waters late afternoon through late evening on Saturday. Otherwise
and elsewhere conditions across the outer waters will remain 
below SCA level through Monday.

For the Inner Waters... There is a twenty percent chance of SCA 
conditions north of Point Conception in the late afternoon and 
evening hours today and Saturday. Otherwise and elsewhere 
conditions across the inner waters will remain below SCA level 
through Monday.

Patchy dense fog will form in the overnight and morning hours in
portions of the coastal waters through the rest of the week.

Increased south swell will result in hazardous conditions for 
mariners through the end of the week, particularly near the surf 


.BEACHES...16/211 AM.

A southerly swell will keep surf heights elevated across the region
through at least Friday evening which will also bring strong rip 
currents and sneaker waves. Surf will be three to six feet on the 
south facing beaches of Ventura and Los Angeles Counties and four 
to seven feet along the Central Coast. 

This swell will slowly diminish through Sunday so the risk of 
moderate to strong rip currents and sneaker waves will also 
diminish but remain a hazard through the weekend.


CA...Beach Hazards Statement in effect through Friday evening for
      zones 40-41-87. (See LAXCFWLOX).



No significant hazards expected.