Scientific Forecaster Discussion
Southwest California area forecast discussion
National Weather Service Los Angeles/Oxnard California
922 am PDT Sat Aug 29 2015
Synopsis...although temperatures will remain above normal today...a
cooling trend is expected through early next week as low pressure
passes to the north. Temperatures will return to near normal by
Sunday...followed by below normal temperatures next week as a trough
of low pressure persists over the West Coast. There will be an
increase in marine layer cloud coverage through next week as well.
Short term (today-mon)...a morning update is not anticipated at
this time. Guidance initialized the southeastward advancing air mass
with a remnant surface front reasonably well. The remnant surface
front oriented NE-SW was extending across the offshore waters at
this time. Guidance was consistent with previous runs and the cooler
and subsiding air mass will advance over the area through Sunday.
Otherwise a Wind Advisory will likely be issued for the Santa Ynez
Mountains this afternoon. The gusty winds will likely prevail
through Sunday morning.
The following is an excerpt from the previous discussion.
The upper high over The Four Corners area will weaken and be forced
eastward as a trough moves toward the Pacific northwest today. Height/thickness
falls...increasing onshore west-east grads and cooling at 850 and 950 mb
should bring several degrees of cooling to most areas today.
However...it still will be rather hot...especially in the
valleys...Lower Mountain elevations and the Antelope Valley...where the
warmest locations will still likely have highs around 100 degrees.
Cooling should be most pronounced on the central coast. The
downsloping northerly winds will likely keep maximum temperatures across southern sba
County from dropping today. In fact...a few locations there may be
warmer than they were on Friday.
A rather strong trough for this time of year will move into the Pacific
northwest tonight and Sunday...then another broad trough will approach the
West Coast Sunday night and Monday. Heights and thicknesses will fall
across the region each day...and onshore gradients will increase.
Expect low clouds to affect the central coast...Santa Ynez
Valley...and l.A. County coast tonight/Sun morning...with more
widespread clouds in coastal areas and some valley areas Sun
night/Monday morning. Decent north-S grads will likely bring gusty winds
again to southern sba County Sun night...and as a result...skies will
probably remain clear there. Maximum temperatures should drop several degrees
on Sunday...then a few more degrees on Monday...bringing temperatures below
normal to most areas. The exception may be right near the
coast...where unusually warm ocean waters will probably help keep
temperatures close to normal Monday.
Long term (tue-fri)...a strong upper low will move into the Pacific northwest
Tuesday. Another trough will move into that region Wednesday night and
Thursday...then slowly move into the northern rockies Friday. This will
maintain a broad trough across the region Tuesday through Friday...with
plenty of night through morning low clouds and fog. Maximum temperatures will
be well below normal for early September in most areas...except
again...close to normal near the coast.
At 1200z...the marine inversion at klax was around 1100 feet deep. The
top of the inversion was around 3100 feet with a temperature of 29
Hi confidence with 12z inland tafs and ksba over the next 24 hours.
Moderate confidence for all other coastal tafs. 30 percent chance
that no ceilings will develop across klgb and klax after 09z sun. There
will be a high confidence chance for low level wind shear around ksba after 21z this
afternoon through at least 08z this evening.
Klax...moderate to hi confidence in the 12z taf. There is a 20
percent chance that LIFR/IFR ceilings will affect the airfield from
about 12z-15z this morning. Otherwise...VFR conditions can be
expected through this 09z...then moderate confidence for IFR conds.
Kbur...hi confidence in the 12z taf with VFR conditions expected at
the airfield through Sunday morning.
Outer waters...northwest winds 15 to 25 miles per hour will persist around Point
Conception this morning...then all outer waters will have northwest winds
15 to 25 knots with gusts to 30 knots this afternoon through Sunday
afternoon. 50 percent chance that gale force wind gusts to 35 knots
will occur across the outer waters by late Sunday afternoon through
early Monday morning. Otherwise Small Craft Advisory level winds
will likely continue into early next week.
Inner waters...80 percent chance for Small Craft Advisory level wind gusts across the
western portion of the Santa Barbara Channel this afternoon through
at least this evening and likely after midnight. Gusts to 30 knots
are possible. Zone 645 from Point Piedras Blancas to Point Sal will
also experience Small Craft Advisory level winds and gusts this afternoon through
tonight. There is a 60 percent chance that a similar pattern could
develop once again Sunday afternoon through early Monday morning.
Small Craft Advisory (see laxmwwlox).
Gale watch (see laxmwwlox).