Area Forecast Discussion
Issued by NWS Los Angeles, CA

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FXUS66 KLOX 262058
AFDLOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
158 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...26/1800Z.

At 1701Z, the marine layer depth was 1260 feet. The top of the
inversion was 4000 feet with a temperature of 23 degrees Celsius.

Good confidence in the 18z TAFs. Expect similar marine cloud
coverage tonight and Thursday morning in spite of a slight
shallowing of the marine layer to around 1000 feet and IFR
conditions. The valley TAFs will not likely see any marine clouds
and the Antelope valley will have another round of gusty
afternoon winds today.
KLAX...Good confidence in 18Z TAF. There is a 30 percent chance of
marine clouds arriving plus or minus two or more hours from the
forecasted time.

KBUR...High confidence in 12Z TAF. There is a 15% chance of IFR
conditions 12Z-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 weeks 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...Sweet
MARINE...Sweet
BEACHES...Sweet
SYNOPSIS...STu

weather.gov/losangeles



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