Area Forecast Discussion
Issued by NWS Los Angeles, CA

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FXUS66 KLOX 231606
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
906 AM PDT Mon Apr 23 2018

.SYNOPSIS...22/901 PM.

There will be overnight and morning coastal low clouds and fog
for several days this coming week otherwise conditions will be
warm and dry. Temperatures will cool a bit Friday and Saturday as
a weak weather system moves across the region.

&&

.SHORT TERM (TDY-WED)...23/905 AM.

As expected this will be a week of marine layer as weak ridging
along with moderate onshore flow will last most of the week.
Minimal day to day changes with low clouds possibly lingering at
or just inland from the coast through the afternoon. Could again
be some patchy dense fog later tonight.

***From previous discussion***

Just a few little changes Tuesday. The ridge is a little weaker
so the marine layer will be a touch deeper and will extend a
little deeper into the vlys. Max temps will cool a little as well.

An upper low approaches northern CA on Wednesday. It will push the
ridge a little more to the east. Hgts...though...really do not
change much. The lift from the trof should lift the low clouds
into the vlys. The inversion will be a little weaker and this will
allow the morning stratus to clear a little quicker. Max temps
will not change much from Tuesday and will be a few degrees above
normal.

.LONG TERM (THU-SUN)...23/318 AM.

EC and GFS agree that the upper low will not move much on
Thursday. Things will be in pretty static pattern and like
Wednesday there will be a deep stratus pattern extending deep into
the vlys. Hgts and pressure grads do not change much and max temps
will be similar to Wednesday`s.

The EC and GFS begin to disagree on the movement and evolution of
the low on Friday but the disagreement if more of a Northern CA
problem as there is not too much difference between the two mdls
for SoCal. Look for a troffier pattern with lower hgts. The deep
marine layer will continue but the lower hgts will usher in a
cooler trend and max temps will fall to a degree or two blo
normal.

Very large disagreement for the forecast next weekend. The EC
brings a tight cut off 552 DM upper low over Sacramento while the
GFS has only a weak trof over the state. The EC seems a little
exuberant and based the weekend forecast on the GFS. Saturday
will be like Friday but by Sunday there should be enough cool air
mixing up north to prevent the stratus from forming across the
Central Coast. The cooler air will also bring max temps down 2 to
4 degrees across the 4 county forecast area.

&&

.AVIATION...23/1040Z.

At 1035Z, the marine inversion at KLAX was based around 900 feet.
The top of the inversion was 2700 feet with a temperature of
22 degrees Celsius.

Overall, low confidence in coastal TAF sites and high confidence
in inland TAf sites. Currently, LIFR/VLIFR conditions prevail at
coastal TAF sites and these conditions should dissipate by late
morning. For tonight, high confidence in return of stratus to
coastal TAF sites, but low confidence in timing and flight
category. For inland sites, high confidence in VFR through the
period (although there is a 20% chance of IFR/LIFR conditions
developing late at KBUR/KVNY)

KLAX...Low confidence in 12Z TAF. Conditions will bounce between
IFR and LIFR 12Z-20Z. Stratus could dissipate up to two hours
earlier than current 20Z forecast. For tonight, high confidence in
return of stratus, but low confidence in timing (+/- 3 hours of
current 03Z forecast) and flight category (50/50 chance of either
MVFR or IFR conditions).

KBUR...High confidence in 12Z TAF. There is a 20% chance of
IFR/LIFR conditions developing after 06Z tonight.

&&

.MARINE...23/811 AM.

Widespread dense fog with visibilities of one mile or less will
likely persist through Tuesday, and maybe through Thursday. The
afternoon and evening hours should be slightly improved, but areas
of reduced visibilities will likely linger.

High confidence in winds and seas remaining below Small Craft
Advisory (SCA strength everywhere through Wednesday. Winds will be
increasing Thursday through Saturday with widespread SCA
conditions and building short period seas likely.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...NONE.

&&

.HAZARD POTENTIAL OUTLOOK (WED-SUN).

No significant hazards expected.

&&

$$

PUBLIC...MW/Rorke
AVIATION...RAT
MARINE...Kittell
SYNOPSIS...Kj

weather.gov/losangeles



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