Area Forecast Discussion
Issued by NWS Los Angeles, CA

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FXUS66 KLOX 270351

751 PM PST Sun Feb 26 2017

The second of two relatively weak weather systems will continue
to bring cool temperatures and a chance of rain and mountain snow
overnight and again on Monday. best chance for rain will be in the
southern portion of the forecast area. High pressure will bring
clear skies and a warming trend beginning in the middle of the



A closed low at 500 mb continues to drop south across the Pacific
Northwest. Ahead of this feature, an elongated stream of
subtropical moisture was seen of IR satellite imagery nearly
parallel to the 30 N latitude line across eastern the Pacific
Ocean into northern Mexico. This moisture will begin shifting
north into far southern California late tonight and persisting
much of the day tomorrow. This will reinforce the low level
moisture already in place as well as increase mid to high level
clouds tonight, mainly to the south of Point Conception with
continued partly to mostly cloudy skies to the north of Point
Conception. Low temperatures tonight will be similar to last
night, with a few degrees of warming with the thicker high clouds
across Los Angeles County.

By Monday, scattered light showers are possible anywhere across
the forecast area, although slightly more likely across far
southern Los Angeles County as the the best moisture and lift with
this feature looks to remain near San Diego County and points
south into the northern Baja Peninsula. Rainfall totals currently
look to remain around a tenth of an inch or less for areas with
showers except locally up to a quarter of a inch possible across
south facing slopes and foothills within Los Angeles County. There
is a strong gradient in rainfall totals with this system to the
south of Los Angeles County. So a minor shift northward of the
moisture could lead to higher amounts then currently represented.
Little change in high temperatures are expected for Monday with
some cooling for areas that saw some sunshine earlier today and to
the north of Point Conception as the cold trough aloft moves
closer to southwest California.

Only minor changes were made to the forecast with Pops reduced
overnight in advanced of the next surge of moisture and highs
tweaked downward to account for increasing clouds to the south of
Point Conception and cooling aloft focused to the north of Point
Conception associated with the trough approaching from the north.

***From previous discussion***

The trough will move over the area through Tuesday morning, with
showers and clouds possibly lingering along the northern slopes.
A cool air mass will remain for Tuesday night for possible
frost/freeze issues along with northerly winds across Southern
Santa Barbara County and through the Interstate 5 Corridor.

Ridging aloft should slowly take hold over the area between
Tuesday night and Wednesday night. The air mass should start to
warm and dry into Wednesday.


A warming and drying trend will take place beneath offshore flow
into late week. Gusty offshore winds could develop, possibly
Wednesday morning across the Los Angeles and Ventura County

Another trough of low pressure should approach the area for next
weekend, but its impact could be limited to only gusty northerly
winds. At least, cooler conditions should develop with the
possibility of more clouds than sun.



At 0000Z, there was a deep moist layer at KLAX with no inversion
to speak of.

Overall, low to moderate confidence in 00Z TAF package. Deep
moist layer will keep low VFR and MVFR CIGs across coastal/valley
TAF sites with a 20-30% chance of localized IFR CIGs with the
light rain that develops. For tonight, expect generally VFR/MVFR
CIGs to continue across Los Angeles county TAF sites. Widely
scattered light showers will continue through tonight and stick
around across LA county into Monday morning.

KLAX...moderate confidence in 00Z TAF. There is a 30% chance of
IFR CIGs 11Z-15Z. For tonight, Easterly wind component could
approach 7 knots between 09z-16z.

KBUR...moderate confidence in 00Z TAF. There is a 30% chance of
IFR CIGs 11Z-15Z. For tonight.


.MARINE...26/130 PM...

For the Outer Waters, moderate confidence in current forecast.
Northwest winds will likely increase to Small Craft Advisory (SCA)
levels late Monday afternoon/Monday evening and continue through
Tuesday night. After a potential lull just below SCA on Wednesday,
winds are expected to increase to SCA levels again

For the Inner Waters, moderate confidence in current forecast. For
the waters north of Point Sal, there is a 40% chance of SCA level
winds developing Monday afternoon and continuing through Tuesday.
Otherwise, winds and seas are expected to remain below SCA levels.
For the waters south of Point Conception, there is a 40% chance of
winds increasing to SCA levels across western sections Monday and
Tuesday. Otherwise, winds and seas are expected to remain below
SCA levels.




No significant hazards expected.



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