Small Craft Advisory 84, NWS Los Angeles, CA

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
1049 PM PDT Mon Jun 12 2017

.SYNOPSIS...
A ridge of high pressure will build over the area into early next
week, supporting the first heat wave of the summer. A prolonged
warming trend is expected this week away from the coast with high
temperatures reaching the 90s for the valleys and 100s further
inland by this weekend and continuing into early next week.

&&

.SHORT TERM...(MON-THU)

Ridging aloft is starting to build in behind a trough of low
pressure now centered near Idaho-Utah Border. The remnant trough
energy will move over the region into Tuesday morning, then exit
permitting the ridge to impact the area. A warming trend will
take shape over the coming days as the high pressure system
centered over the Eastern Pacific Ocean slowly builds. 500 mb
heights will climb and 950 mb temperatures will warm into late
week. Summerlike temperatures will descend on the area for the
latter half of the week with some of the warmest location hitting
the century mark. Onshore flow should continue over the area into
Thursday as onshore pressure gradients remain.

A northerly surface pressure gradient across the area this evening
will continue into Tuesday morning. A wind advisory remains in
effect for the Santa Barbara South Coast through 9 am Tuesday
morning, but an advisory was also added for mainly the Interstate
5 Corridor portion of the Los Angeles and Ventura County
Mountains through 9 AM Tuesday morning, as well. Motorists,
especially those driving high-profile vehicles are urged to use
caution due to the potential for strong cross winds.

An update will be issued shortly.

*** FROM PREVIOUS DISCUSSION ***

Gusty north winds expected to return to southern SB County
Thursday but this time with much warmer temps. Coastal temps could
jump into the high 80s there late Thursday as the sundowners
start to kick in.

.LONG TERM...(FRI-MON)

Heat really the main story through the period. The ridge will
really become established Friday and basically not move through
the middle of next week, thus this heat wave will be here for
awhile. The combination of the warming aloft and weak onshore
gradients will lead to probably the warmest coast/valley day
through Sunday as onshore gradients and a weak eddy return over
the weekend. However, this won't have any impact on temperatures
farther inland such as the mountains, Antelope Valley, and
interior SLO/SB counties where temps will climb a couple degrees
each day through the period. We will be getting at least close to
excessive heat warning levels across the far interior Friday and
through the weekend but with forecast lows expected to remain
mostly in the 60s in the populated areas there will be some
overnight relief.

On Monday onshore gradients again start to weaken and the upper
ridge actually strengthens from the southeast. So look for
additional warming for all areas beginning the week. With 950mb
temps approaching 44c in the Antelope Valley and 42c across far
interior SLO County we could be looking at highs approaching 110
out there. No relief expected in this through Thursday as models
in excellent agreement maintaining the strong ridge along the west
coast. The one mitigating factor is that gradients still remain
onshore through the period, so for the coastal areas at least
there will be a sea breeze to keep temps from getting too hot and
possibly even a very shallow marine lyr.

&&

.AVIATION...

13/0600Z

At 00Z at KLAX, the marine layer was 800 feet deep. The top of the
inversion was around 1700 feet with a temperatures of 19 degrees
Celsius.

Very good confidence in TAFs. There is a 20 percent chc of IFR
cigs 12Z-16Z at KLAX...KLGB and KSMO. There is a 30 percent chc
KSMX will remain VFR through the period.

KLAX...Very good confidence in TAFs. There is a 20 percent chc of IFR
cigs 12Z-16Z.

KBUR...High confidence in CAVU TAF.

&&

.MARINE...

12/100 PM.

High confidence in strong NW winds through tonight from Point Sal
to San Nicolas Island including the western portion of the Santa
Barbara Channel. Winds should be similar to last night. Not sure
if the winds will truly hit Gale (34+ KT) but confident gusts
will exceed 30 KT. Elsewhere Small Craft Advisory (SCA) conditions
for winds or steep seas are likely. The winds should weaken by
about 5 KT everywhere Tuesday and Wednesday and shift to the
north. High confidence of SCA conditions from the Central Coast
down to San Nicolas Island. The Santa Barbara Channel and Santa
Monica Basin could see brief SCA winds but likely will not. Seas
however will remain choppy with short periods dominant. NW winds
could increase overall Thursday and Friday with Gale Conditions
once again possible. Dense fog could also become a concern toward
the middle to end of the week.

&&

.FIRE WEATHER...

12/200 PM.

High confidence in extended period of elevated fire danger across
interior sections of Southwest California Tuesday through early
next week due to prolonged period of hot and dry conditions along
with drying fuels. The low level flow will become weakly offshore
on Tuesday morning across interior sections, with local north
to northeast winds gusting to between 25 and 35 mph across the
mountains and Santa Clarita Valley. This brief offshore flow
will bring significant warming and drying on Tuesday, with
humidities falling to between 10 and 20 percent across many
interior areas.

The heat wave is expected to build through the week and persist
through early next week, with widespread readings into the 90s
across inland areas. Triple digit heat will become likely at times
Friday through early next week across the Antelope Valley, as
well as warmest interior valleys, and lower mountains. The hot
and unstable conditions later this week into early next week
could lead to plume dominated fire potential, especially in the
foothills and mountains.

Many interior sections will see humidities fall into the teens
and single digits each day during this heat wave. Starting
Wednesday night, there will be warm overnight low temperatures and
poor humidity recoveries in the foothills and mountains that
would enable active burning at night in these areas. During this
extended period of hot and dry weather, there will be elevated
fire danger Tuesday through at least early next week across
interior sections, with the greatest threat being potential rapid
spread of grass fires and other fine fuels.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory in effect until 9 AM PDT Tuesday for zones
      39-52>54. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect until 9 PM PDT Tuesday for
      zone 645. (See LAXMWWLOX).
     Gale Warning in effect until 3 AM PDT Tuesday for zones
      650-673-676. (See LAXMWWLOX).
     Small Craft Advisory in effect until 3 AM PDT Tuesday for
      zone 655. (See LAXMWWLOX).
     Small Craft Advisory in effect until 3 AM PDT Wednesday for
      zone 670. (See LAXMWWLOX).

&&

.HAZARD POTENTIAL OUTLOOK...(THU-MON)
Hot, dry and gusty sundowner winds possible in southern Santa
Barbara County Thu/Fri nights. Hot temperatures 12-18 degrees
above normal are expected, mainly for interior sections Wednesday
through Monday.

&&

PUBLIC...Hall/MW
AVIATION...Rorke
MARINE...Kittell
FIRE...Gomberg
SYNOPSIS...Munroe

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