Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Southwest California area forecast discussion 
National Weather Service Los Angeles/Oxnard California
230 PM PST Monday Dec 22 2014

Synopsis...
high pressure aloft and offshore flow will bring warm and breezy
conditions to the area tonight and Tuesday. Low pressure will
develop across the Great Basin on Wednesday and Thursday...and will
bring cooler conditions to the area. For the weekend...the low
pressure will keep wobbling over the Great Basin...resulting in
temperatures remaining near seasonal normals and could generate some
gusty canyon winds.

&&

Short term (today-thu)...
overall...12z models in good synoptic agreement through the period.
At upper levels...ridge centered to the southwest will remain
dominant feature through Tuesday...then an inside slider will work
its way into the Great Basin Wednesday/Thursday. Near the surface
moderate offshore flow will prevail through Tuesday...then shift
onshore Wednesday...to be followed by a good northerly flow on
Thursday.

In the immediate short term...satellite shows some clouds hanging
tough across interior sections of slo/sba counties and some clouds
along the la coast...otherwise clear skies. Overnight...expect the
clouds across interior slo/sba counties to remain with some dense
fog developing. As for the clouds/dense fog along the la coast
will expect those clouds to dissipate by late this evening.

Main story tonight and Tuesday will be offshore winds. 12z models
do not indicate anything to deviate from previous thinking. With
a strong offshore lax-dag gradient (-6.7 mb) and decent upper level
and thermal support...still anticipate moderate northeast winds
across Ventura and Los Angeles counties. Current suite of wind
advisories look good and will remain in place. As for temperatures
expect the coastal plain to be the warmest locations on Tuesday as
some cold air advection (associated with the offshore winds) bring a
bit of cooling to the valleys and mountains. Either way...still a
very comfortable day temperature-wise.

For Tuesday night/Wednesday...there will be some lingering northeast
flow through Wednesday morning (and there could be a chance of some
low end advisory level winds continuing). However by Wednesday
afternoon expect onshore flow to return as inside slider begins to
dive into the Great Basin. So...will anticipate cooler temperatures
for all areas Wednesday afternoon.

For Wednesday night/Thursday...inside slider will result in noticeably
cooler temperatures (coastal/valley temperatures in the lower to middle 60s).
Additionally...there will be the potential for some light showers
across interior sections of slo/sba counties as well as the north
slopes of the Ventura/la mountains. Will keep mention of slight
chance probability of precipitation for these areas with the afternoon forecast. Also...there
should be some increasing northerly winds during the day on Thursday
and would not be surprising to have some advisory-level northerly
winds through the Santa Ynez range and I-5 corridor by late Thursday
afternoon and evening.

Long term (fri-mon)...
for the extended...models continue to exhibit decent synoptic
agreement. At upper levels...ridge will recover a bit on Friday...but
for the weekend and into early next week...a series of inside
sliders will carve out a significant trough over the interior west.
Near the surface...there should generally be a continued north to
northeasterly flow pattern...most significant during the night and
morning hours.

Forecast-wise...nothing too Earth-shattering is anticipated through
the period. Only anticipate minor day-to-day changes in temperatures
as the overall pattern will keep coastal/valley temperatures in the
60s. As for winds...there will be periods of some gusty north to
northeast winds...and advisories could be required through the
weekend.

&&

Aviation...22/1800z.
Good confidence in the 18z forecasts despite a troubling patch of
marine clouds just off the coast of klax. Elsewhere...skies are
clear and will remain so for the next 24 hours...except in the
Salinas valley where kprb will experience another bout of dense fog.

Klax...some doubt about klax staying clear for the next 24 hours
with a patch of marine clouds lurking just offshore. Only moderate
confidence in the taf forecast as there is a 30 percent chance of
LIFR to vlifr conditions sometime during the night.

Kbur...high confidence in VFR conditions for the next 24 hours.

&&

Marine...22/0900 am.
Gale warnings are expected to subside this afternoon...although
there is a possibility that they may return late Wednesday night and
Thursday morning. Small craft advisories will continue in the outer
waters through this evening. The inner waters below passes and
canyons may have Small Craft Advisory level winds Tuesday morning as
the offshore flow increases winds in that area.

&&

Lox watches/warnings/advisories...
Wind Advisory (see laxnpwlox).
Small Craft Advisory (see laxmwwlox).
High rip current risk (see laxsrflox).

&&

$$

Public...rat
aviation/marine...Sweet
synopsis...rat

Www.Weather.Gov/losangeles

National Weather Service Glossary of Abbreviations