Area Forecast Discussion
Issued by NWS Los Angeles, CA

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339
FXUS66 KLOX 260602
AFDLOX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
1102 PM PDT Tue Jul 25 2017

.SYNOPSIS...
Dry southwest flow aloft and building high pressure will
gradually warm temperatures this week to a few degrees above
normal. Overnight and morning low clouds will continue along the
coast.

&&

.SHORT TERM...(TUE-FRI)

The monsoonal moisture in place the last couple of days is slowly
starting to stabilize and dry as drier southwest flow aloft
entrains into the flow and the surface loses solar insolation.
Mentions of showers and thunderstorms have been removed from the
forecast for tonight in the latest update.

A high pressure system centered over Texas will slowly build in
into the Four Corners Region through late Thursday. As it does, a
warming trend will develop due to weakening onshore flow and a
thinning marine layer. NAM-WRF time height sections across the
area continues to indicate a similar trend with the near-surface
moisture getting squashed each day through Thursday and remaining
shallow into Friday. A few tweaks have been made to the forecast
based upon the latest data, but otherwise, the forecast seems on
track.

*** FROM PREVIOUS DISCUSSION ***

Temperatures could reach toward dangerously hot levels across
portions of the area on Friday and a heat advisory could needed
Friday for the Los Angeles and Ventura County Mountains, if this
trend continues.

.LONG TERM...(SAT-TUE)

The ridge aloft weakens some while pushing into Northern Arizona
over the weekend as the remnant moisture from Hurricane Hilary
could get embedded in the flow around the high pressure system.
GFS and ECMWF solutions hint at some semblance of an easterly wave
moving over the region. A slight chance of showers and
thunderstorms remain in the forecast over the weekend over the
Mountains and Desert and into early next week as a low confidence
forecast looks to develop.

Some model differences start to develop over the weekend and into
early next week. Both model solutions agree that the high pressure
system will strengthen to near 598 dm over the Great Basin some
time between Tuesday and late next week. While agreement exists
for further warming, timing will be difficult to place as much
will depend upon the movement of the remnants of Hurricane Hilary.

&&

.AVIATION...26/0600Z

At 0530Z at KLAX, the marine layer depth was near 1100 feet. The
top of the inversion was around 2200 feet with a temperature near
23 degrees Celsius.

Low confidence in coastal TAFs as marine layer clouds are slow to
develop. Fair confidence in CIG hgts but timing could be off by as
much as three hours. There is a 40 percent chc that KVNY will see
IFR cigs 13Z-16Z. Good confidence in all TAFS after 19Z.

KLAX...Low confidence in TAF through 10Z. MVFR cigs could arrive
anytime between 07Z and 10Z. SCT conds could occur any time from
1630Z-1800Z. Good confidence in TAF from 19Z-06Z and lower
confidence with arrival of low clouds.

KBUR...There is a 40 percent chc the terminal will stay VFR. High
confidence in TAF after 16Z.

&&

.MARINE...25/800 PM...

For the Outer Waters, good confidence in current forecast. Winds
and seas will remain below Small Craft Advisory (SCA) levels
through Thursday. For Friday and Saturday, winds may increase to
SCA levels in the far north portion.

For the Inner Waters, good confidence in current forecast. For the
waters north of Point Sal, winds and seas are expected to remain
just below SCA levels through Saturday. For the waters south of
Point Conception, winds and seas will remain below SCA levels
through Saturday.

&&

.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...(FRI-TUE)
A significant surf event could develop late Thursday as swells
from Hurricane Hilary arrive at the Southern California beaches.
High surf and strong rip currents will occur from Friday through
Sunday.

&&

$$

PUBLIC...Hall
AVIATION...Rorke
MARINE...Sweet/Sirard
BEACHES...Sweet
SYNOPSIS...Smith

weather.gov/losangeles



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