224 
FXUS66 KLOX 182117
AFDLOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA 
217 PM PDT Sun Jun 18 2017

.SYNOPSIS...
A persistent and strong upper level ridge over the region will 
allow for very hot conditions across interior locations, including
the Antelope Valley. Night through morning low clouds across 
coastal areas S of Point Conception are expected the next couple 
days. A modest cooling trend is expected by the end of the week.

&&

.SHORT TERM...(TDY-WED)

The marine stratus ran north this morning from the south coast,
around Point Conception and arrived along the central coast up to
Morro Bay where it is expected to remain through the evening. The
overall pattern is similar to yesterday and afternoon temperatures
will end up a couple of degrees warmer. The heat wave remains the
main story. While mostly affecting areas further inland, downtown
LA will be about five degrees above normal today and will warm 
even more through Tuesday before finally getting back down to 
normal on Saturday. Temperatures in the Antelope Valley will rise
to around 110 during the peak of the event on Tuesday.

Onshore flow which will help to keep coastal zones fairly mild 
once again today. The NE portion of the AV is expected to reach 
around 40 degrees Celsius. This should translate to highs reaching
105 to 108 across Lancaster/Palmdale and near 110 near Saddleback
Butte. An Excessive Heat Warning went into effect this morning for
the Antelope Valley through at least Wednesday. Expect highs to 
range between 107-112 Monday thru Wed. This may even be extended 
through Thursday. There will be triple digit heat in some of the 
lower mountain elevations. A heat advisory is in effect for the 
mountains, interior SLO county, and the Cuyama Valley through 
Wednesday evening as well. Upgrading the Advisory to a Warning for
the LA County mountains on Monday morning, and for the San Luis
Obispo County mountains and interior valleys on Tuesday morning. 
Expect high temps to range between 103-108 for these locations 
over the next few days. High temps across the Santa Clarita Valley
will be reaching the lower 100s today. Highs in the San Fernando 
and San Gabriel Valleys as well as the Ventura County Valleys will
reach the mid to upper 90s but a bit cooler nearer the coast to 
the lower 90s. 
 
There will be areas of patchy smoke today around Santa Clarita 
Valley and Antelope Valley from the fire burning near Castaic 
Lake.

Models continue to show an eddy circulations across the LA/VTU
coastal waters and should expect some kind of stratus to redevelop
tonight into Monday and possibly again Monday night into Tue
morning but remain limited to coastal areas. The heat will really
be on Mon/Tue across the interior areas with a few more degrees of
warming for the valleys, mountains, and the interior areas as well
as the Antelope Valley where as already mentioned highs reaching
110 degrees will be likely each day.

Wednesday will remain hot away from the coast, but temperatures 
will begin to fall with slight height falls, but they will remain 
above 590 DM.

.LONG TERM...(THU-SUN)

There should be a few degrees of relief starting Thursday for 
inland areas, but still quite hot across the AV. Expect 3-5 
degrees of cooling across valleys with this modest cooling trend 
continuing through Sunday. Highs will still remain above normal 
for most areas away from the immediate coast. Some night through 
morning low clouds are expected along the LA/VTU coast and 
possibly the SBA South Coast, and some patchy low clouds and fog 
could affect the portions of the Central Coast as well.

&&

.AVIATION...18/12z

At 08Z at KLAX... the inversion was around 700 ft. The top of the
inversion was around 2600 ft with a temperature of about 24 degrees
Celsius.

Overall... Moderate confidence in the current coastal TAFs and 
higher confidence in the inland TAFs. Through 18z VLIFR/LIFR 
conditions at coastal sites south of Point Conception and at KSMX 
will waft in and out during this period due to the influence of the 
Catalina eddy. Through 18z there is a twenty percent chance of 
LIFR/IFR conditions at KSBP... KVNY... and KBUR. Similar conditions 
are likely to return after 19/07z. Otherwise and elsewhere VFR 
conditions will prevail through the forecast period.
 
KLAX... Moderate confidence in the current TAF. Through 18z VLIFR/LIFR
conditions will waft in and out due to the influence of the 
Catalina eddy. Otherwise VFR conditions will prevail. Similar
conditions are likely to return after 19/09z. No east winds 
greater than 7 knots are expected.

KBUR... Moderate to high confidence in the current TAF. Through 
18z there is a twenty percent chance of LIFR/IFR conditions.
Otherwise VFR conditions will prevail through the forecast 
period.

&&

.MARINE...18/200 PM...

Low clouds and local fog continues to cover sections of inner
waters from Los Angeles to San Luis Obispo County this afternoon.
The central coast is the most difficult forecast but currently 
looks more entrenched than anywhere else. Low confidence about
amount of fog in this area, but do expect widespread visibilities
to one mile or less across southern coastal waters late tonight
and Monday morning. Winds are generally light through Monday.
There will be an increase in south swell mixing with westerly
swell Tuesday through Thursday. 

For the outer waters, areas of fog with visibilities less than 
one mile possible tonight through Monday. West to northwest swell
builds to 8-10 ft Tuesday through Thursday and expect gusty 
northwest winds getting into SCA levels starting Monday night for 
the northwest sector of zone 676 and zones 670-673.  

For the inner waters, winds and seas will remain below SCA levels
through Thursday.

&&

.BEACHES...18/900 am.

A mixture of south and west swell and building high tides will 
bring increasing rip current risk to the Ventura and Los Angeles 
County coasts through the week. The peak days will be Tuesday 
through Thursday when larger surf heights will lead to strong and 
dangerous rip currents at the beaches and a significant risk for 
ocean drowning. This risk will be compounded by the extended 
period of very hot temperatures over the inland areas next week 
which will lead to more people at the beaches and in the water 
than usual. 

This is a serious risk. Beaches with active lifeguard patrols are
typically the safest, however, beachgoers should always ask 
lifeguards about known rip current areas before going into the 
water. Stay alert to the ocean conditions and updates about this 
building rip current risk during the week.

&&

.FIRE WEATHER...18/950 AM. 

High pressure aloft continues to build over Socal through Tuesday
bringing 2-4 degrees of warming Sunday through Tuesday away from 
the immediate coast. The combination of increasing temperatures 
and shrinking marine layer will cause humidities to falling up to
5 percent interior areas and up to 15 percent interior coastal 
areas into the valleys by Tuesday. This will result in triple 
digit heat for interior areas including many valley locations by 
Tuesday with minimum humidities of 10 to 25 percent range away 
from the coast except for single digits for the Antelope Valley 
and higher elevations possibly including the Carrizo Plain into 
the Cuyama Valley.

Winds through Wednesday be on the lighter side except for 
diurnally driven onshore winds for interior areas with gusts 
generally up to around 30 mph except for downsloping areas like 
the foothills of the Antelope Valley with gusts up to around 40 
mph. Onshore winds will likely increase 5 to 10 mph Thursday. The 
onshore winds will likely transport smoke from the Lake Fire 
through the mountains and possibly reaching western portions of 
the Antelope Valley each afternoon and evening while the fire is 
active.

The combination of increasing temperatures and lowering 
humidities will bring continued elevated fire weather conditions 
for interior areas through Thursday with brief critical conditions
possible in wind prone areas such as the 14 corridor into the 
foothills of the Antelope Valley early next week. Additionally, 
the hot and unstable weather conditions with generally light winds
could lead to plume dominated fire potential, especially in the 
foothills and mountains, including the Lake Fire. Gusty and
erratic winds are possible near the Lake Fire if it becomes plume
dominated.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory in effect until 11 AM PDT Tuesday for zones
      37-51. (See LAXNPWLOX).
     Excessive Heat Warning in effect from 11 AM Tuesday to 9 PM
      PDT Wednesday for zones 37-51. (See LAXNPWLOX).
     Heat Advisory in effect until 9 PM PDT Wednesday for zones
      38-52-53-88. (See LAXNPWLOX).
     Heat Advisory in effect from 11 AM Tuesday to 9 PM PDT
      Wednesday for zone 41. (See LAXNPWLOX).
     Heat Advisory in effect from 11 AM Monday to 9 PM PDT
      Wednesday for zones 44>46-547. (See LAXNPWLOX).
     Heat Advisory in effect until 11 AM PDT Monday for zone 54. (See LAXNPWLOX).
     Excessive Heat Warning in effect from 11 AM Monday to 9 PM
      PDT Wednesday for zone 54. (See LAXNPWLOX).
     Excessive Heat Warning in effect until 9 PM PDT Wednesday for
      zone 59. (See LAXNPWLOX).
PZ...NONE.

&&

.HAZARD POTENTIAL OUTLOOK...(WED-SUN)
Hot temperatures and potential heat impacts are likely for inland
and mountain areas and across the Antelope Valley. Impacts are 
expected to be greatest Wednesday, especially over the Antelope 
Valley where high temperatures Wednesday are expected to be 
around 110 degrees. Temperatures will remain above normal until at
least Saturday.

&&

$$

PUBLIC...jld
AVIATION...Kj
MARINE...EB
BEACHES...EB
FIRE...Munroe
SYNOPSIS...B

weather.gov/losangeles