Scientific Forecaster Discussion
fxus66 klox 141243
Area forecast discussion...updated
National Weather Service Los Angeles/Oxnard California
543 am PDT Mon Oct 14 2019
..updated aviation discussion...
Most locations across the region will start the week generally
cool, become warm and dry mid week, then turn cool again by the
end of the week. Gusty north winds will develop late in the week
and continue into the weekend.
Short term (tdy-wed)...14/502 am.
A 1400 ft marine layer over klax and an 800 ft marine layer over
kvbg along with clear skies and onshore flow have produced a Hodge
podge of marine stratus this morning. Stratus will likely continue
to form and coverage will be more organized by dawn. The marine
inversion as well as the onshore flow is pretty weak so clearing
should be complete by mid to late morning.
A dry trof is moving down in the northwest flow through the center of the
state. It is not affecting the weather too much save for lowering
the hgts to 570 dm. The onshore flow and lower hgts will make
today the coolest of the next 7. Max temps will be down 3 to 6
degrees from ydy and will end up 2 to 4 degrees blo normal.
Ridging follows fast on the heels of todays trof. Hgts will rise
and the gradients will shift to offshore. The marine layer
stratus will be pushed out to sea everywhere except for the la
southern coastal sections. There will be some northwest canyon winds but
with only weak gradients and no thermal or upper support the winds
will only be of the 15 to 25 mph variety. Max temps will jump 5
to 10 degrees and will be above normal across the board.
Wednesday will be much like Tuesday with the only exception being
the central coast where falling hgts in the afternoon will bring a
few degrees of cooling.
Long term (thu-sun)...14/307 am.
The ec and the GFS are in remarkable agreement through the
extended period bringing increased confidence in the forecast.
Large broad scale trofing is forecast to move in on Thursday. The
west/east grad turns onshore but the north/S grad turns more offshore. The
decent offshore push to the north will limit the stratus
development. The lower hgts and reversal of offshore push to the
west will lower temps 5 to 10 degrees most everywhere and almost
all areas will see slightly below normal temps.
Dry northwest flow will set up on Friday in the wake of the departing
trof. The flow will become more and more northerly through the
weekend and will also increase in speed. The big news with the Fri
through sun forecast is the offshore gradients specifically the north
to S grad which becomes more an more offshore each day. This
offshore push will greatly limit stratus development. The west/east flow
does not change much during the time. Since offshore flow to the
west contributes much more to warming than offshore flow to the
south, Max temps will only warm slightly each day. The sba South
Coast could be the exception as that area will have advisory
level sundowners each evening. These north winds could have a
significant warming effect over the city of sba. There will also
likely be low end advisory level gusts through the I-5 corridor.
Models continue to show this northerly wind even rapidly evolve
into a moderate to strong Santa Ana on Monday. This evolution
will be closely monitored.
At 0754z at klax, the marine layer was 2000 ft deep. The top of
the inversion was near 2500 ft with a temperature of 14 c.
Good confidence for Desert/Valley tafs. Moderate confidence in
coastal tafs. VFR transition may occur any time between 15z and
18z. For ksmx, there is a 30% chance of LIFR conditions after 06z.
For klax and klgb, low clouds may arrive as early as 03z.
Klax...moderate confidence in taf through 18z. VFR transition
could occur anytime between 16z and 18z. Good confidence in taf
18z-03z then lower confidence as low clouds may arrive as early
as 03z. Good confidence in an east wind component under 5 kt.
Kbur....high confidence in ceiling and visibility unlimited taf.
High confidence that winds and seas will remain below Small Craft
Advisory (sca) criteria through Tuesday over all of the coastal
waters. Wind speeds are expected to increase over the waters along
the central coast and southward towards San Nicolas Island on
Wednesday afternoon. Good confidence in Small Craft Advisory level winds over
these waters on Wednesday night, then become strong Small Craft Advisory level to
possibly near gale force on Thursday and Friday. Good confidence
in these Small Craft Advisory level winds reaching the western portion of the Santa
Barbara Channel. Increasing confidence in a long-period, large northwest
swell arriving Thursday and lasting through at least the weekend.
Patchy dense fog is likely across the coastal waters north of
Point Conception through the morning.
Hazard potential outlook (wed-sun).
Gusty sundowner winds are expected for southern Santa Barbara
County Thursday through Sunday. Gusty northerly winds also
possible for the Interstate 5 corridor region Friday through