Area Forecast Discussion
Issued by NWS Los Angeles, CA

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796
FXUS66 KLOX 240916 AAA
AFDLOX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
216 AM PDT Tue Oct 24 2017

.SYNOPSIS...
Strong high pressure aloft and moderate Santa Ana conditions will
bring continued record heat to many areas into today. The ridge
will break down through Thursday, allowing for a gradual cooling
trend. A ridge of high pressure may try to rebuild early this
weekend, bringing a rebound in temperatures.

&&

.SHORT TERM...(MON-THU)

Many record highs were reached across the forecast area today,
including 106 degrees at Camarillo, 105 at Long Beach, and 102 at
downtown Los Angeles. There were a total of 10 record highs broken
or tied. Please see the latest Record Report (LAXRERLOX) for details.

Skies were clear across the forecast area this evening, and will
continue to remain clear through the night. Very warm conditions
continue this evening, with many temps still in the mid 80s to low
90s. The latest ACARS sounding from LAX show a temperature of 94
degrees around 1500 ft. With offshore flow continuing tonight, low
temps should be very warm in the breezy to windy areas from the vlys
to the foothills, where lows should only fall into the mid 70s to
lower 80s.

Gusty NE winds continued over the mountains and some of the vlys
of VTU/L.A. Counties, where wind gusts of 30 to 40 mph were noted.
Winds are forecast to increase and become more widespread
overnight across the L.A./VTU mtns, vlys and coastal areas. 850 mb
winds are forecast by the 00Z NAM to increase to 40 to 45 kt over
a large part of the mtns, while 950 mb winds top out in the 50 to
55 kt range early Tue morning over srn VTU County and sw L.A.
County including around the Santa Monica range. Gusts in the hier
mtns could approach 55 mph in some areas, with local gusts up to
60 mph possible in the Santa Monica mtns. By late tonight into Tue
morning, NE winds are expected to gust to 45 to 55 mph for the
sern VTU County vlys, San Fernando Vly, Santa Clarita vly, coastal
areas of VTU County and the L.A. County coast from Malibu to the
Hollywood Hills. These winds will persist thru Tue morning then
diminish some Tue afternoon. Wind Advisories are in effect for all
of these areas.

An unusually strong 597 dm upper level high was centered over nrn CA
this evening. This upper level high will persist in this general
area thru Tue then gradually weaken thru Wed. Upper level ridging
will linger along the CA coast Wed night and Thu. 500 mb heights
over SWrn CA will be 594-595 dm on Wed, lower to 587 dm for Wed and
to around 586 dm for Thu. 1000-500 mb thicknesses will be around 580
dm Tue, then fall to 578 dm Wed and to 576 dm on Thu.

Skies over the forecast area will remain clear thru Thu. Offshore
winds will increase some Tue night into Wed morning, but will not be
quite as strong altho advisory-level gusts will continue to be
possible in some of the vlys at times. Weak offshore flow will
prevail Wed night into Thu morning, then onshore flow will develop
sooner on Thu.

The continued very warm 950 mb and boundary layer temps, and high
1000-500 mb thicknesses will combine with the offshore flow to bring
another exceptionally hot day to the area on Tue, where Excessive
Heat Warnings remain in effect. Many of the coast and vlys are
expected to top out in the 95 to 105 degree range, even near the
coast. Please see the latest Non-Precipitation Weather Message
(LAXNPWLOX) for further details on the Wind Advisories and
Excessive Heat Warnings.

It looks like temps will be down 3 to 5 deg overall on Wed then cool
another 3 to 5 deg for Thu. Even so, temps will continue to be
several degrees above normal in all areas thru Thu.

***FROM PREVIOUS DISCUSSION***

.LONG TERM...(FRI-MON)

The ridge will persist into Friday only to be replaced by a
smaller ridge poking in from the SW over the weekend. While it
doesn`t look like the marine layer will return in strength over
the weekend, it does appear that the RH levels will finally rise
above the 10-20 percent levels with at least some high clouds
helping to cool things down. The jet drops down over our area on
Monday and that may finally be enough to get our pattern back to
more seasonal for late October.

&&

.AVIATION...

24/0916Z...

At 0515Z at KLAX, there was no marine layer. There was a sfc based
inversion with a top of 500 ft and a temperature of 35 deg C.

Hi confidence in CAVU TAFs. Ocnl LLWS and lgt turbc will occur
over and near to higher terrain.

KLAX...Hi confidence in CAVU TAF. There is only a 10 percent chc
of an easterly wind greater than 8 kt.

KBUR...Moderate confidence CAVU TAF with MVFR blowing dust/ash
layer through 22Z. Ocnl LLWS and lgt turbc 14Z-22Z.

&&

.MARINE...

23/840 PM

For the Outer Waters, high confidence in current forecast. Winds
and seas are expected to remain below Small Craft Advisory (SCA)
levels through Friday for PZZ670/673. For PZZ676, there is a 70%
chance of SCA level northeast winds Tuesday and a SCA has been
issued.

For the Inner Waters, high confidence in current forecast. For the
waters north of Point Sal, winds and seas will remain below SCA
levels through Friday. For the waters south of Point Conception,
SCA level winds are likely from Ventura south to Santa Monica
today through Wednesday with the strongest winds in the morning to
early afternoon hours. On Tuesday morning through early afternoon,
there is a 70% chance of Gale force gusts, but the coverage of
these gusts are expected to be localized and likely close to the
coast.

There is a chance that the northeast winds will reach Avalon and
Two Harbors on Tuesday, but since this is a hot Santa Ana event
the likelihood of significant winds out that far is small. 30
percent chance of 10-20 KT winds in the harbors, 10 percent chance
of 15-25 KT.

&&

.FIRE WEATHER...

23/100 PM

A moderate to locally strong Santa Ana wind event will bring
windy, hot and very dry conditions through Wednesday to much of
Los Angeles and Ventura Counties. This event is especially
concerning because of the multiple day nature of it, which we have
not seen yet this season and such events have a history of large
fires. The winds will peak on Tuesday with 20 to 30 mph gusting to
50 mph common in the wind prone coastal and valley areas of Los
Angeles and Ventura Counties, and 20 to 35 mph gusting to 60 mph
common in the mountains. Minimum humidities of 6 to 12 percent
will be common through Wednesday, with poor overnight recoveries.
Widespread record breaking heat will exasperate the situation,
with highs between 95 and 105 common and lows between 65 and 75
common. Some windy and hilly locations may only drop into the 80s
at night. A Red Flag Warning will remain in effect through
Wednesday as a result. Over San Luis Obispo and Santa Barbara
Counties, similar heat and dry air is expected, but easterly winds
peaked on Sunday and should locally gust between 20 and 30 mph in
the wind prone areas. As such, elevated fire weather conditions
exist there.

With these prolonged weather conditions, and the very dry
fuels/vegetation, extreme fire behavior is likely if any fire
ignition begins...threatening life and property. The public
should be very, very careful with any potential ignition sources
such as welding and brush clearing equipment, as well as campfires
and cigarettes.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory in effect until 8 PM PDT Tuesday for zones
      34>36-39-88. (See LAXNPWLOX).
     Excessive Heat Warning in effect until 8 PM PDT Tuesday for
      zones 40-41-44>46-87-547. (See LAXNPWLOX).
     Wind Advisory in effect until 2 PM PDT Wednesday for zones
      40-41-44>46-53-54-88-547. (See LAXNPWLOX).
     Red Flag Warning in effect until 6 PM PDT Wednesday for zones
      240-241-244>246-253-254-288-547-548. (See LAXRFWLOX).
PZ...Small Craft Advisory in effect until 3 PM PDT Tuesday for
      zones 650-655-676. (See LAXMWWLOX).

&&

.HAZARD POTENTIAL OUTLOOK...(THU-MON)
Heat advisory level temperatures may continue for many areas into
Wednesday. Gusty northeast winds will likely impact wind prone
areas of Los Angeles and Ventura Counties through early
Wednesday. Hot, dry and windy conditions will likely bring
continued critical fire weather conditions to some areas
Wednesday.

&&

$$

PUBLIC...Sirard/jld
AVIATION...Rorke
MARINE...Munroe/Sweet
FIRE...Kittell
SYNOPSIS...Munroe

weather.gov/losangeles
FXUS66 KLOX 000000 CCA
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
158 AM PST SAT JAN 16 2016

.SYNOPSIS...

A SERIES OF WEAK FRONTAL SYSTEMS ARE EXPECTED TO MOVE THROUGH THE
AREA DURING THE NEXT SEVEN DAYS...BRINGING THE POSSIBILITY OF LIGHT
RAIN MAINLY TO THE NORTH OF SANTA BARBARA. OTHERWISE SURFACE HIGH
PRESSURE ALOFT WILL SUPPORT FAIR SKIES AND SEASONABLE TEMPERATURES.

&&

.SHORT TERM (TODAY-MON)...A WEAKENING COLD FRONT WAS BEGINNING TO
MOVE ACROSS THE CENTRAL COAST THIS MORNING. THIS FRONT WILL
CONTINUE TO PUSH THROUGH MUCH OF SAN LUIS OBISPO AND SANTA BARBARA
COUNTIES THIS MORNING. THE MAIN UPPER LOW ASSOCIATED WITH THIS
COLD FRONT LOCATED WELL NORTH OFF THE WASHINGTON STATE COAST WILL
MOVE TO THE NORTHEAST ALLOWING THE FRONT TO WEAKEN EVEN FURTHER.
THE FRONT SHOULD WASH OUT AS IT MOVES ACROSS THE SOCAL BIGHT. THERE
WILL BE ISOLATED SPRINKLES ACROSS PORTIONS OF VENTURA COUNTY
LATER THIS MORNING. THE NW FLOW WITH THIS SYSTEM WILL LIKELY LEAVE
L.A. COUNTY DRY. HOWEVER THERE WILL BE LOW CLOUDS AND PATCHY FOG
ACROSS COAST AND COASTAL VALLEYS OF L.A. COUNTY THIS MORNING.
PATCHY DRIZZLE IS POSSIBLE AS WELL. BEHIND THE FRONT...BREEZY W
TO NW WINDS ACROSS THE ANTELOPE VALLEY AND I-5 CORRIDOR WILL
PREVAIL LATE THIS MORNING THROUGH THIS AFTERNOON. WINDS WILL
REMAIN BELOW WIND ADVISORY THRESHOLDS. THERE SHOULD BE PARTLY
CLOUDY SKIES FOR AREAS N OF POINT CONCEPTION BY EARLY
AFTERNOON...WHILE AREAS TO THE SOUTH SHOULD EXPERIENCE PARTLY TO
MOSTLY CLOUDY SKIES MUCH OF THE DAY.

HIGH TEMPS WILL REMAIN SIMILAR TO WHAT WE HAVE SEEN OVER THE LAST
WEEK OR SO. HIGHS MAINLY IN THE LOWER TO MID 60S FOR COAST AND
VALLEYS. FOR TONIGHT THROUGH SUNDAY...SKIES SHOULD REMAIN PARTLY
CLOUDY WITH SOME MORNING LOW CLOUDS AND PATCHY FOG ONCE AGAIN FOR
THE LA/VTU COUNTY COAST AND COASTAL VALLEYS. THERE WILL BE SOME
WEAK OFFSHORE WINDS IN THE MORNING BUT NOT SURE IT WILL BE STRONG
ENOUGH TO SCOUR OUT THE MORNING LOW CLOUDS. THE WEAK OFFSHORE
WINDS WILL TURN ONSHORE BY THE AFTERNOON. THE SHORTWAVE RIDGE WILL
QUICKLY BREAKDOWN AS ANOTHER WEAK COLD FRONT MOVES INTO NRN
CALIFORNIA. ITS LIKE A SCENE OUT OF GROUNDHOGS DAY...AS ANOTHER
REPEAT OF THE PREVIOUS STORM IS SET TO OCCUR AGAIN ON SUNDAY
EVENING INTO MONDAY MORNING. LIGHT RAIN EXPECTED FOR AREAS N OF
POINT CONCEPTION...WITH ONLY A SPRITZ OF RAIN POSSIBLE FOR LOS
ANGELES AND VENTURA COUNTIES MONDAY MORNING. SHOWERS SHOULD ABATE
BY THE AFTERNOON WITH PARTLY SUNNY SKIES IN THE AFTERNOON.

.LONG TERM (TUE-FRI)...
BOTH GFS AND ECMWF ADVERTISE ANOTHER FRONTAL BOUNDARY MOVING INTO
THE CENTRAL COAST ON TUESDAY. THE GFS HAS BEEN FLIP-FLOPPING ON
THE STRENGTH OF THE COLD FRONT. THE EC IS MUCH WEAKER AND MORE
CONSISTENT. THEREFORE FEEL LIKE THE WEAKER EUROPEAN MODEL WOULD
BE MORE TRUSTWORTHY. HOPEFULLY AS WE DRAW CLOSER...THE MODELS
WILL BE IN SYNC WITH THE SPEED AND STRENGTH OF STORM. ONCE
AGAIN...LIGHT RAINFALL AMOUNTS TO THE NORTH...WITH LESS THAN A
TENTH OF AN INCH FOR LA/VTU COUNTIES. A RIDGE BEHIND THE FRONT
WILL BUILD. THIS WILL HELP WARM THE COAST AND VALLEYS UP A FEW
MORE DEGREES BOTH WED AND THU. NO RAIN EXPECTED ON WED/THU FOR THE
FORECAST AREA HIGHS SHOULD REACH THE LOWER 70S BY MID WEEK. AND
YET ANOTHER UPPER TROUGH IS EXPECTED TO SWING SOUTHEAST INTO
CENTRAL CALIFORNIA...THEN SPREAD OVER SOUTHERN CALIFORNIA BY
FRIDAY AFTERNOON.


&&

.AVIATION...16/0600Z.

AT 0522Z...THERE THE MARINE LAYER WAS AT 2900 FEET WITH A WEAK
INVERSION TO 5400 FEET. TEMPERATURE WAS 8 DEGREES C AT 5400 FT.

NORTH OF KSBA...LOW CONFIDENCE IN THE 06Z TAFS DUE TO UNCERTAINTY IN
CIGS/VSBYS DUE TO LIGHT SHOWERS EXPECTED THROUGH 16Z AS A WARM FRONT
PUSHES THROUGH THE REGION. THERE IS A 30 PERCENT CHANCE OF IFR
CIGS/VSBYS LASTING UP TO THREE HOURS DURING MODERATE SHOWERS AS THE
WARM FRONT PUSHES THROUGH MAINLY FROM 16/08Z TO 16/14Z.

KSBA AND SOUTH...MODERATE CONFIDENCE IN THE 06Z TAFS TO DUE
UNCERTAINTY IN TIMING AND HEIGHT OF CIGS...EXCLUDING KPMD AND KWJF
WHERE VFR CONDITIONS ARE EXPECTED TO PREVAIL. THERE IS A 30 PERCENT
CHANCE OF IFR CIGS FOR THESE TAF SITES. TIMING OF CIGS MAY BE OF BY
+/-2 HOURS. THERE IS A 20 PERCENT CHANCE OF ISOLATED SHOWERS BETWEEN
15Z & 21Z WITH LESS THAN A 10 PERCENT CHANCE FOR KPMD & KWJF.

KLAX...LOW TO MODERATE CONFIDENCE IN THE 06Z TAF DUE UNCERTAINTY IN
TIMING AND HEIGHT OF CIGS EXCLUDING KPMD AND KWJF WHERE VFR
CONDITIONS ARE EXPECTED TO PREVAIL. TIMING OF CIGS MAY BE OF BY +/-2
HOURS. THERE IS A 30 PERCENT CHANCE OF IFR CIGS BETWEEN 12Z & 20Z.
EAST WINDS BETWEEN 16/08Z & 16/21Z ARE EXPECTED TO REMAIN BELOW 7
KTS. THERE IS A 20 PERCENT CHANCE OF ISOLATED SHOWERS BETWEEN 15Z &
21Z. THERE IS A 40 PERCENT CHANCE OF IFR CIGS/VSBYS AFTER 17/06Z.

KBUR...MODERATE CONFIDENCE IN THE 06Z TAF DUE UNCERTAINTY IN TIMING
AND HEIGHT OF CIGS EXCLUDING KPMD AND KWJF WHERE VFR CONDITIONS ARE
EXPECTED TO PREVAIL. TIMING OF CIGS MAY BE OF BY +/-2 HOURS. THERE
IS A 20 PERCENT CHANCE OF ISOLATED SHOWERS BETWEEN 15Z & 21Z. THERE
IS A 40 PERCENT CHANCE MVFR CIGS MAY CONTINUE PAST 03Z.

&&

.MARINE...15/800 PM...

LOCAL GUSTS TO 25 KT ARE POSSIBLE NEAR PT CONCEPTION AND IN THE
VICINITY OF THE CHANNEL ISLANDS LATE SATURDAY AFTERNOON AND EVENING.
OTHERWISE...WINDS SHOULD GENERALLY REMAIN BELOW SMALL ADVISORY
CRITERIA THROUGH TUESDAY. A LARGE NW SWELL OF 15-17 FEET AT 18-20
SECONDS WILL ENTER THE COASTAL WATERS N OF PT CONCEPTION SATURDAY
NIGHT. SMALL CRAFT ADVISORIES FOR HAZARDOUS SEAS WILL BE NEEDED FOR
THE CENTRAL COAST...ALL OUTER WATERS...AND POSSIBLY WESTERN PORTIONS
OF THE INNER WATERS. SEAS WILL LIKELY REMAIN ABOVE 10 FT THROUGH AT
LEAST TUESDAY. THE LARGE SWELL WILL PRODUCE BREAKING WAVES AT THE
MORRO BAY AND VENTURA HARBOR ENTRANCES SUNDAY THROUGH MONDAY...WHEN
THE SWELL IS EXPECTED TO PEAK.

&&

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY (SEE LAXMWWLOX).
HIGH SURF ADVISORY (SEE LAXCFWLOX).
HIGH RIP CURRENT RISK (SEE LAXSRFLOX).
MARINE WEATHER STATEMENT (SEE LAXMWSLOX).

&&

$$

PUBLIC...KAPLAN
AVIATION/MARINE...MUNROE
SYNOPSIS...SUKUP

WWW.WEATHER.GOV/LOSANGELES



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