Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

000 
FXUS66 KLOX 222203
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA 
203 PM PST Tue Jan 22 2019

.SYNOPSIS...22/1238 PM.

Sunny skies will prevail today with temperatures slightly below 
normal. Gusty offshore winds will continue through Wednesday 
across many mountain and valley areas. Temperatures will 
gradually warm to above normal through the week as conditions 
remain dry and sunny.

&&

.SHORT TERM (TDY-FRI)...22/159 PM.

Strong and gusty N to NE winds persisted early this afternoon across 
much of the mtns and foothills of L.A./VTU Counties, with some gusty 
winds lingering in some of the adjacent valleys, and coastal areas 
especially below passes and canyons of the L.A. County coast from 
Leo Carillo to the Hollywood Hills. Recent gusts included 60 mph at 
at Chilao RAWS, 47 mph at Mill Creek RAWS, and 46 mph at Malibu 
Hills RAWS. Many of these areas will continue to have advisory-level 
winds through the rest of the afternoon, with Wind Advisories 
continuing. 

Otherwise, mostly sunny skies with some hi clouds were noted over
the forecast area early this afternoon, with little change 
expected thru sunset. Temps will be slightly warmer than 
yesterday but remain below normal for the most part. Highs in the 
warmest vlys and inland coastal areas should reach the mid to 
upper 60s, mainly over VTU/L.A. Counties.

A rather deep upper level trof over the southern Great Basin this 
afternoon will gradually move off to the E thru tonight. An upper 
level ridge of high pressure well off the CA coast this afternoon 
will expand E and into CA tonight thru Wed, with 500 mb heights over 
SW CA increasing to near 584 dm on Wed. The upper ridging will 
persist along and off the CA coast Wed night thru Fri, altho by Thu 
afternoon a weak upper level trof will approach the area from the N. 
This weak upper trof should move along the CA/NV border Thu night, 
then another sharper upper level trof should move into this area 
from the N on Fri. 

The strong and gusty N to NE winds will persist through Wed morning 
over the mtns, foothills and many vlys of VTU/L.A. Counties, as well 
as the L.A. County coast mainly from Malibu to the Hollywood Hills. 
Wind Advisories are in effect through Wed morning for all of these 
areas. Expected peak wind gusts range from 45 to 55 mph in the mtns 
and foothills, and generally 40 to 50 mph elsewhere in the Advisory 
areas. Please see the latest Non-Precipitation Weather Message 
(LAXNPWLOX) for further details on the ongoing Wind Advisories. 

Additional sub-advisory offshore winds will prevail night and 
morning hours for many of these areas into Thu, then another round 
of advisory level winds can be expected Thu night into Fri morning 
as offshore gradients increase substantially (NAM predicted 
gradients for LAX-DAG at 12Z Fri is -7.5 mb). 

Mostly clear skies with a few hi clouds at times will prevail across 
the forecast area tonight through Fri. Temps are forecast to rebound 
to near normal to slightly above normal for many areas on Wed. It 
will be warmer on Thu and Fri with above normal temps just about 
everywhere thanks to offshore flow and warming at 850 mb and in the 
boundary layer. Look for highs in the warmest vlys and inland 
coastal areas to reach the upper 60s to mid 70s on Wed, and 
generally in the 70s on Thu and Fri. Low temps will also be quite 
cool again tonight with the coldest sheltered vlys dropping to near 
or slightly above freezing, especially over SLO/SBA Counties. It 
looks like widespread frost is likely for the SLO County interior 
vlys, with freezing conditions in the mid to upper 20s expected for 
the Antelope Vly.

.LONG TERM (SAT-TUE)...22/159 PM.

The EC and GFS are in generally good agreement with the synoptic 
features over the ern Pac to western U.S. for Sat thru Tue. The 
upper level ridging along and off the CA coast will build and 
expand into CA over the weekend, with 500 mb heights reaching to 
586 dm or so by early Sun. The upper level ridge will then slowly 
weaken Mon and Tue while moving back to or just off the CA coast. 
Dry weather with mostly offshore flow will prevail across the 
forecast area thru the extended period.

Gusty offshore winds night and morning hours can be expected across 
swrn CA Sat, with gusts possibly reaching advisory levels in the 
wind-prone areas. Sub-advisory offshore flow can be expected into 
Sun, with a transition to some weak onshore flow on Mon. Offshore 
gradients should increase quickly Mon night into Tue morning, with 
support for possible advisory-level or even stronger northeast winds 
during that time especially over portions of VTU/L.A. Counties. 

Mostly clear skies will continue across the region Sat thru Sun, 
then some mid and hi level clouds should move in for Mon with 
partly cloudy skies as a whole. Mostly clear skies can then be 
expected across the area for Tue.

Temps are forecast to be several degrees above normal for many areas 
Sat thru Sun. Temps for Mon should drop to slightly above normal for 
the most part, then to near to slightly above normal for Tue. Highs 
in the warmest vlys and inland coastal areas should reach the mid 
70s to near 80 on Sat, 70s on Sun, and upper 60s to lower 70s Mon 
and Tue.

&&

.AVIATION...22/1740Z.

At 1800Z, there was no marine inversion at KLAX.

Moderate to high confidence in 18Z TAF package. High confidence 
in VFR conditions for all sites through the TAF period. However, 
moderate confidence in wind forecast due to uncertainty of timing 
of changes in direction/strength. 

KLAX...High confidence in 18Z TAF. VFR conditions are anticipated
through the TAF period. There is a 60% chance that light northerly
cross winds will continue until 20Z. There is a 30% chance of 
LLWS 18Z-23Z. 

KBUR...High confidence in 18Z TAF. VFR conditions are anticipated
through the TAF period. Moderate confidence in north to northeast
winds through 21z. There is a 40% chance of LLWS and strong 
UDDFs.

&&

.MARINE...22/202 PM.

For the Outer Waters, high confidence in current forecast. Winds
and seas are expected to remain below Small Craft Advisory (SCA)
levels through Saturday. 

For the Inner Waters north of Point Sal, high confidence in
current forecast. Winds and seas are expected to remain below SCA
levels through Saturday.

For the Inner Waters south of Point Concpetion, moderate
confidence in current forecast. There is a 50% chance of SCA 
level northeast winds again late tonight and Wednesday. Otherwise,
winds and seas are expected to remain below SCA levels through 
Friday. On Saturday, there is a 50% chance of SCA level northeast 
winds developing again, from Ventura southward.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory in effect until noon PST Wednesday for zones
      41-44>46-53-54-88-547. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect until 3 PM PST this afternoon
      for zones 650-655. (See LAXMWWLOX).

&&

.HAZARD POTENTIAL OUTLOOK (FRI-TUE).

Advisory level north to northeast winds will be possible night 
and morning hours Fri and Sat for wind-prone areas of Ventura and
Los Angeles Counties. These areas may have advisory-level to 
possible high wind warning level wind gusts Mon night into Tue.

&&

$$

PUBLIC...Sirard

National Weather Service Glossary of Abbreviations