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fxus66 klox 211817 
afdlox

Area forecast discussion
National Weather Service Los Angeles/Oxnard California
1017 am PST Tue Feb 21 2017

..aviation and marine discussions updated...

Synopsis...

Light rain will linger today. A low will move into Nevada tonight
with breezy north winds and possible precipitation for the
mountains through Wednesday night. The clouds will decrease into
Friday...and temperatures should be about normal by the weekend.
A storm should approach from the north on Saturday and spread
precipitation by Sunday. The precipitation could continue into
Monday.

&&

Short term...(tdy-thu)

A narrow band of mid-to-upper level moisture is showing up well
on radar right now over Los Angeles County. While the radar looks
more ominous than it is (being high based) it is a bit of a
surprise, and leads to a better chance for some light but
measurable rain (under 0.10 inches) for la County. Upped pops as
a result. To the north, low level moisture is interacting with the
southwest flow aloft once again today. Radar for slo to Ventura
counties is showing some low reflectivities, but this is very much
under- representing the rain because the moisture is so close to
the ground. With steady light rain falling there now, upped pops
to near 100 percent...though additional amounts will be light and
mainly in the 0.10 to 0.25 inch neighborhood. The low- level
nature of this rain will also make interior areas hard pressed to
get rain as the mountains will block a lot of it, but a few
showers could squeeze through. Rain still looks good to taper off
quickly later today and tonight...but low confidence on exactly
when as it could quickly shut off this afternoon or linger into
the evening.

***From previous discussion***

An inside slider moves down the California/Nevada line tonight. It is pretty
dry but it will shift the winds to the north which will pile up
clouds and a few showers on the north slopes. Otherwise skies
should turn partly cloudy across the coasts and vlys. Despite the
additional sunshine the Max temps will fall a couple of degrees as
cold air filters in behind the trof. The winds will keep the
clouds and scattered showers going through the day. Snow levels
will fall through the day but should remain above the Grapevine
Pass level.

It looks like advisory level wind gusts will develop across the la
vta and sba mountains as well as the Antelope Vly Wednesday night.
The winds will be strongest through the I-5 corridor. It will also
be gusty in the Santa Clarita Vly and the area either side of the
vta/la County border. Clouds and a few showers will remain on the
north slopes. Snow levels will get close to the pass levels.

The barest of ridges will move into the area Thursday. Skies will
be mostly sunny. It will remain breezy but right now it looks like
the winds will be below advisory criteria. Max temps will warm a
couple of degrees but will still be below normal.

Long term...(fri-mon)

Both the GFS and the ec agree that dry zonal flow will be over the
state on Friday and Saturday. Skies will be mostly clear
Friday...but Saturday will see a slow increase in clouds as a new
system begins its run into the state. Max temps will increase each
day and Saturday will be the warmest of the next 7 with Max temps
coming in only a degree or two below normals.

Both the ec and the GFS are in fair agreement that a cool upper
low embedded in the base of it much larger parent trof will rotate
down the coast and then into the center of the state. If the
current mdl forecast is right light rain will overspread the area
Saturday night. The cold front with moderate rain will move over
the area during the day Sunday. Showers will then move in behind
the front and keep the area wet Sunday night and Monday. Would
like to see a few more mdl runs before fully jumping on this rain
bandwagon as frequently there are changes to both timing and
intensity of these storms as the event draws closer.

&&

Aviation...21/18z...

At 17z at klax... there was no notable inversion.

Overall... moderate confidence in the current tafs. The reduced
confidence is due to the variability of the cigs and vsbys and in
the timing of the passing storm. IFR/MVFR conditions will
generally prevail across the region through 20z-22z except for
the Antelope Valley terminals. Conditions will improve through
01z-03z then diminish to MVFR conditions by 10z at most coastal
and adjacent valley locations through 17z. Otherwise and elsewhere
VFR conditions will prevail.

Klax... moderate confidence in the current taf. The reduced
confidence is due to the variability of the cigs and vsbys and in
the timing of the passing storm. A forty percent chance of MVFR
conditions developing periodically through 21z. Conditions will
diminish to MVFR 10z through 17z. Otherwise VFR conditions will
prevail. No east winds above 5 knots are expected during the
forecast period.

Kbur... moderate confidence in the current taf. The reduced
confidence is due to the variability of the cigs and vsbys and in
the timing of the passing storm. A forty percent chance of MVFR
conditions developing periodically through 21z. Conditions will
diminish to MVFR 10z through 17z. Otherwise VFR conditions will
prevail.

&&

Marine...21/830 am...

Small Craft Advisory (sca) level seas will persist through
tonight across the outer waters and along the central coast.
Northwest winds will increase to Small Craft Advisory level across all coastal
waters on Wednesday and persist through Thursday night. Winds
will diminish to below Small Craft Advisory levels on Friday then strengthen again
on Saturday and likely reach Small Craft Advisory levels across the outer waters
and along the central coast.

&&

Lox watches/warnings/advisories...
California...high surf advisory in effect until 4 PM PST this afternoon
for zones 34-35. (See laxcfwlox).
Pz...Small Craft Advisory for hazardous seas in effect until 3 am
PST Wednesday for zones 645-670-673-676. (See laxmwwlox).

&&

Hazard potential outlook...(thu-mon)
snow levels below 4,000 feet Wednesday night could result in
light Snow Mountain and Interior Valley roads including the Tejon
Pass. Gusty north winds are expected Wednesday and Thursday which
will create hazardous Road conditions and possible downed trees.
More rain and wind is expected over the weekend.

&&
$$

Public...kittell/rorke
aviation...kj

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