Area Forecast Discussion
Issued by NWS Los Angeles, CA

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000
FXUS66 KLOX 270032
AFDLOX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
532 PM PDT Wed Jul 26 2017

.SYNOPSIS...

A warm air mass with fair skies will persist into the weekend.
Early next week, monsoonal moisture could possibly bring showers
and thunderstorms to the Ventura and Los Angeles mountains and
deserts as the remnants of Hurricane Hilary move north.

&&

.SHORT TERM...(TDY-SAT)

The latest visible imagery shows cloud build ups over the
Mountains and Desert this afternoon as some monsoonal moisture
clings onto the area. Primarily partly cloudy skies will develop
this afternoon and evening. An isolated shower cannot be ruled
out later today, but any shower that develop would likely be
short-lived and rain amount would not amount to much.

Otherwise, high pressure aloft centered over Eastern New Mexico
this afternoon will gradually build west into the Four Corners
Region through Friday. 500 mb heights climb and 1000-500 mb
thickness values increase through late week. A warming trend will
occur through at least Thursday, and possibly into Friday. The
latest 18Z NAM-WRF model solutions are starting to back off on
Friday being the warmest day as an eddy circulation develops over
the coastal waters, which should strengthen onshore pressure
gradients. Regardless, temperatures will likely remain on the high
side of normal for Friday. Less stratus coverage will likely
develop over the next several days. The best confidence in stratus
coverage is for the Central Coast portion, while less confidence
exists for the South Coast portion.

.LONG TERM...(SUN-WED)

The forecast gets a bit more unclear for early next week. GFS and
ECMWF model solutions diverge in the timing of the remnants
Hurricane Hilary and maybe the combo of the remnants of Hurricane
Hilary and Irwin for early next week. GFS solutions are more
aggressive relative to the ECMWF model solutions in bringing
remnants into Southern California. Unfortunately, GFS ensemble
members offer little help in the finer details and perturbations
of the model diverge as well. High confidence exists in a warm air
mass remaining, possibly humid at times. Less confidence exists
in the timing of the rain chances next week, a blanket of slight
chance PoPs is in the forecast for now until better confidence
exists.

&&

.AVIATION...27/0030Z.

At 00Z, the marine layer depth was around 1250 feet. The top of
the marine inversion was around 2000 feet with a temperature near
22 degrees Celsius. There was another inversion above up to around
4000 feet.

LIFR to IFR conditions will likely spread into coastal terminals
through 13Z, then continue through at least 16Z. VFR conditions
should redevelop between 16Z and 18Z. There is a chance of VLIFR
conditions at terminals north of KSBA between 08Z and 14Z.

KLAX...There is a 70 percent chance of IFR conditions developing
between 07Z and 13Z, then continuing through at least 16Z or 17Z.

KBUR...VFR conditions are expected throughout the period. There is
a 20 percent chance of MVFR visibilities between 10Z and 16Z.

&&

.MARINE...26/200 PM.

For the Outer Waters, good confidence in current forecast. Winds
and seas will remain below Small Craft Advisory (SCA) levels
through Thursday night. On Friday and Saturday, there is a chance
of SCA level winds across PZZ670/673. Winds should decrease below
SCA levels across all the Outer Waters on Sunday.

For the Inner Waters, good confidence in current forecast. For all
the waters, winds and seas are expected to remain below SCA levels
through Sunday.

&&

.BEACHES...26/200 PM.

Hurricane Hilary is expected to slowly weaken today. In spite of
the weakening trend, it will generate a southeasterly swell that
will impact Southern California beaches this weekend. The
southeasterly swell will move into the coastal waters early
Saturday, then peak on Monday or Tuesday. High surf conditions as
well as strong rip currents will be likely across south-facing
beaches this weekend. The latest model runs have backed off a bit
on the wave heights, but a high surf advisory still looks likely.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Beach Hazards Statement in effect from Friday morning through
      Tuesday evening for zones 40-41-87. (See LAXCFWLOX).
PZ...NONE.

&&

.HAZARD POTENTIAL OUTLOOK...(SAT-WED)

A significant surf event should peak over the weekend as swells
from Hurricane Hilary arrive at the Southern California beaches.
High surf and strong rip currents will occur from through the
weekend.

&&

$$

PUBLIC...Hall
AVIATION...Hall
MARINE...Sweet
BEACHES...Sweet
SYNOPSIS...STu/Hall

weather.gov/losangeles


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