Area Forecast Discussion
Issued by NWS Los Angeles, CA
FXUS66 KLOX 220141
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
541 PM PST Tue Feb 21 2017
Showers will linger into the evening tonight from a low pressure
system along the California Coast. The low pressure system should
move into Nevada tonight resulting in gusty winds and possible
precipitation for the northern slopes of the mountains into
Wednesday night. Less cloudiness and warmer temperatures will
develop Thursday and Friday. A storm system could bring rain and
mountain snow to the area over the weekend.
The light rain showers continue to impact SBA and Ventura
Counties this afternoon, but still expecting these to taper off
this evening as the flow shifts to northwesterly. A little
uncertain honestly if the shut off will be closer to 4pm or
midnight. Other areas may see a light shower or two into the
The trough that is causing all this light rain will move into
northern California on Wednesday...which shift the flow from
southwesterly to northwesterly. Winds at the surface will turn
more northerly as early as tonight...then increase
Wednesday...and stay gusty through Thursday night. The wind prone
areas (like the I-5 Corridor & Antelope Valley & southern SBA
County) should see advisory level gusts to 50 mph. Will be
issuing that advisory shortly. The north flow will also help clear
things out Wednesday and Thursday on the coastal side of the
mountain ranges...with periods of sunshine and highs in the 60`s.
On the backside however moisture will pile up starting tonight and
result in a number of showers...especially from the Tejon Pass to
Cuyama. While snow levels should stay above 5,000 feet tonight
into Wednesday...they still look to lower to around 3,500
Wednesday night into Thursday. This should result in light snow
over interior roadways (including the I-5 Tejon Pass, Highway 166
and Forest Road 95)...which could accumulate and cause hazardous
By Friday, the flow turns slightly more easterly, which will kill
the north slope showers. This will also bring an extra dose of
warming...but the airmass will remain cold and temperatures will
continue to be at or below normal.
Rain still looks likely over the weekend...with Saturday night and
Sunday looking like the main window of opportunity. A weak trough
currently over the Aleutian Islands will drop into the northern
California waters on Saturday and join forces with a low currently
1600 miles west of San Francisco. This new system looks to push
through central California on Sunday.
While there is growing confidence for rain, the details remain
fuzzy. There is a real potential for moderate rain in the
0.50-1.50 inch (in 6 hours) neighborhood which is what the GFS is
showing, but the 12Z ECMWF came in frustratingly light. Based on
the deepness of the low would have to lean toward the wetter
solution, but the ECMWF has been performing better than the GFS of
late...leading to some shoulder shrugging.
Computers are projecting another low working down the coast which
would slow the progression of the Sunday system. If this scenario
plays out, temperatures would remain below normal with ample
clouds and general chances of showers through Monday or Tuesday.
Not putting too much stock in this just yet...as there is just too
much run-to-run variability with the weekend.
At 00z, there was a weak marine inversion based around 500 feet at
KLAX. The top of the inversion was around 1000 feet with a
temperature around 14 degrees Celsius.
Low-to-moderate confidence in the current forecast. Conditions
will improve through 05Z, except for IFR to MVFR conditions near
any rain/showers. There is a chance of IFR to MVFR conditions
between 08Z and 16Z. There is a slight chance of LIFR conditions,
mainly between 08Z and 16Z. VFR conditions should redevelop
between 15Z and 19Z. Periods of moderate to strong wind shear and
turbulence are possible between Wednesday afternoon and night.
KLAX...There is a 50 percent chance of IFR to MVFR conditions near
any showers/rain through 08Z. There is a 30 percent chance of IFR
to MVFR conditions between 08Z and 16Z. VFR conditions should
redevelop between 17Z and 19Z. North winds greater than 10 knots
are possible on Wednesday evening.
KBUR...There is a 60 percent chance of IFR to MVFR conditions
near any showers/rain through 08Z. There is a 30 percent chance of
IFR to MVFR conditions between 08Z and 16Z. VFR conditions should
redevelop between 17Z and 19Z.
Small Craft Advisory (SCA) level seas will persist through
tonight across the outer waters and along the Central Coast.
Northwest winds will increase to SCA level across all coastal
waters on Wednesday and persist through Thursday night. Winds
will diminish to below SCA levels on Friday then strengthen again
on Saturday and likely reach SCA levels across the outer waters
and along the Central Coast.
CA...High Surf Advisory in effect until 3 PM PST Wednesday for
zones 34-35. (See LAXCFWLOX).
Wind Advisory in effect from 3 PM Wednesday to 10 AM PST
Thursday for zones 39-52>54. (See LAXNPWLOX).
High Surf Advisory in effect from noon Wednesday to 9 PM PST
Thursday for zones 40-41-87. (See LAXCFWLOX).
Wind Advisory in effect from 3 PM Wednesday to 3 AM PST
Thursday for zone 59. (See LAXNPWLOX).
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...(FRI-TUE)
More rain and wind is expected over the weekend.