Area Forecast Discussion
Issued by NWS Los Angeles, CA

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FXUS66 KLOX 231201
AFDLOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
401 AM PST Mon Jan 23 2017

...Aviation discussion updated...

.SYNOPSIS...

Showers, isolated thunderstorms, and mountain snow will continue
through Tuesday as a cold low pressure system moves overhead.
Showers may linger into Tuesday, then dry weather is expected
Wednesday into the weekend as a large ridge of high pressure
develops.

&&

.SHORT TERM...(TDY-WED)

Overnight the weather regime switched from heavy rain to showers.
The strong southerly flow ahead of yesterdays front brought a long
period of moderate to heavy rain to the area making it the
rainiest day since Dec 2010. Yesterday was the rainiest day in
Long Beach`s history. A cold and very unstable air mass will move
over the area today. Satellite shows a very broad area of showers
and TSTMs embedded in fast moving cyclonic flow. Today will be a
very variable weather day. It will be cloudy at times then partly
cloudy at others. It will be dry at times and then showery. The
big weather news today is the TSTM threat. LI`s fall through the
day and will reach -5 this afternoon. There will be a chc of TSTMs
everywhere today with the best chc over SLO and SBA counties.
there is a fair amount of CAPE and any TSTM that forms will be
very capable of producing small to medium sized hail. Any TSTM
and a few of the heavier showers that form today will be capable
of producing rainfall rates near 1 inch per hour which will be
capable of producing flash flooding. Since there has been so much
rain over the past few days there is a chc of flash flooding
everywhere not just the burn areas. Low snow levels and gusty
winds will combine to make for hazardous winter conditions in the
mtns where a winter storm warning continues. Rainfall amounts
today will be highly variable due to the showery nature of the
system. On average the area will see about a quarter inch of
additional rainfall but there will be some areas that see more and
some areas that will see hardly any additional rain. 542 DM hgts
will make for a rather cool day today with max temps 12 to 16
degrees blo normal.

The system will begin to wind down tonight and the showers will
diminish. The biggest problem will be the low snow levels which
will allow for snow showers over Interstate 5.

On Tuesday the upper low that is spinning off of the Oregon coast
will become incorporated into a large scale trof rotating out of
Canada. The main energy of this system will stay to the west and
best chc of rain will be over the outer waters and the Central
coast. A little warmer but not much and max temps will remain well
below normal.

And then a dry pattern will set up over the area as a ridge moves
in. A few more degrees of warming but max temps will still only be
near 60 across the coasts and vlys.

.LONG TERM...(THU-SUN)

Ridging will persist through the extended period. A little inside
slider will move through the flow pattern Thursday and may kick
off a little wind event. Ridging will peak and decent offshore
flow will develop for the weekend.

Max temps will warm slowly through Friday but will remain blo
normal. Good warming to set in for the weekend with normal to
slightly above normal max temps.

The cold airmass and the clearing skies will keep min temps
several degrees blo normal.

&&

.AVIATION...23/12Z.

At 09z at KLAX...there was no notable inversion.

Overall... Only moderate confidence in the TAFS. Scattered
showers with mostly IFR/MVFR conditions across the region through
tonight with frequent changes in CIGs and VSBYs especially near
any thunderstorms. Thunderstorms chances are ten to fifteen
percent. VFR conditions will prevail north of Point Conception
after 08z and south of Point Conception after 03z.

KLAX... Only moderate confidence in the TAF. Scattered showers
with mostly IFR/MVFR conditions through tonight with frequent
changes in CIGs and VSBYs especially near any thunderstorms.
Thunderstorms chances are ten to fifteen percent. No east winds
above 7 kts are expected during the forecast period. VFR
conditions will prevail after 03z.

KBUR... Only moderate confidence in the TAF. Scattered showers
with mostly IFR/MVFR conditions through tonight with frequent
changes in CIGs and VSBYs especially near any thunderstorms.
Thunderstorms chances are ten to fifteen percent. VFR conditions
will prevail after 03z.

&&

.MARINE...23/200 AM.

Seas and swells are diminishing but will remain elevated through
Tuesday. Breaking waves will continue over Morro Bay and Ventura
Harbor entrances as well as near the shoreline and breakwalls
through today. Small Craft Advisory level winds will continue
across most of the coastal waters through this afternoon and
hazardous seas will continue through Tuesday morning.

Moderate confidence in thunderstorms across the coastal waters today.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...High Surf Advisory in effect until 6 PM PST Tuesday for zones
      34-35-39>41-87. (See LAXCFWLOX).
     Flash Flood Watch in effect through this afternoon for zones
      34>41-44>46-51>54-59-87-88-547. (See LAXFFALOX).
     Winter Storm Warning in effect until 6 PM PST this evening
      for zones 52>54. (See LAXWSWLOX).
     Wind Advisory in effect until 9 AM PST this morning for zone
      59. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect until 6 AM PST Tuesday for
      zones 645-650-655-670-673-676. (See LAXMWWLOX).

&&

.HAZARD POTENTIAL OUTLOOK...(WED-SUN)
No significant hazards expected after Day 2. See the LOX
Watches/Warnings/Advisories for products concerning the current
storm.

&&
$$

PUBLIC...Rorke
AVIATION...Kj
MARINE...Kj
SYNOPSIS...Sukup

weather.gov/losangeles



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