Area Forecast Discussion
Issued by NWS Los Angeles, CA
FXUS66 KLOX 230410
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
910 PM PDT Wed Mar 22 2017
Isolated showers and thunderstorms will continue through this
evening. For Thursday and Friday, dry and warmer conditions are
expected along with some northerly winds. By Friday night and
Saturday, a weak storm system will bring another shot of rain to
the area. For early next week, high pressure will build over the
area, resulting in dry and warmer conditions.
Scattered showers and thunderstorms developed this afternoon across
portions of the forecast area, mainly over the mtns and into the
Antelope Vly, in response to a cold upper level trof. The activity
has been stubborn into early this evening, with scattered showers
and thunderstorms persisting mainly over VTU/L.A. County mtns,
Antelope Vly and Santa Clarita Vly. Several spotter reports from the
Santa Clarita Vly indicated thunderstorms with lots of small hail
and heavy rain. As the steering flow shifts more nw, some activity
was beginning to push into vlys s of the Santa Clarita Vly.
Scattered showers and thunderstorms should continue for a while this
evening before ending probably by late this evening. Otherwise,
partly to mostly cloudy skies should prevail for the most part
overnight, altho a clearing trend should take place after midnight.
There may even be a few upslope rain and snow showers on the n mtn
slopes overnight, with snow levels down to 4500 feet or lower not
out of the question, possibly affecting travel over the Grapevine.
Gusty mainly sub-advisory w to nw winds will continue for many areas
this evening before diminishing overnight, altho should persist in
the mtns and Antelope Vly thu late tonight.
Rather vigorous upper level trof moving over CA this evening. The
upper trof will move quickly e overnight into Thu morning, with
upper level ridging building into the area by Thu afternoon. The
upper ridge will linger over the area into Fri morning, with a fast-
moving upper trof and surface cold front expected to approach the CA
coast by later in the day. This upper trof will move quickly into CA
later Fri night into Sat morning then move e of the region Sat
Dry weather can be expected Thu thru Fri morning, with clear to
partly cloudy skies overall, except becoming mostly cloudy over
SLO/SBA Counties Fri morning as the upper trof and surface cold
front approaches. A few showers may move into the Central Coast Fri
afternoon, but then the front is expected to push in Fri night with
widespread mainly light rain over SLO/SBA Counties, and a chance of
rain and mountain snow developing for VTU/L.A. Counties. The chances
of rain and mountain snow should diminish thru the day on Sat as the
cold front weakens and moves e of the area. Rainfall amounts on Sat
are difficult to pin down, but should be one quarter to one half
inch over SLO/SBA Counties, except up to an inch possible in the
nwrn SLO County foothills. For VTU/L.A. Counties, rainfall looks to
be one tenth of an inch or less. Skies should be mostly cloudy
across the forecast area on Sat.
Temps are forecast to be several degrees below normal on Thu, then
warm to slightly below normal on Fri, except slightly above normal
in the Antelope Vly. Temps should cool back down to several degrees
below normal again on Sat. Highs in the warmest vlys and inland
coastal areas should reach the mid to upper 60s Thu, upper 60s to
low 70s Fri, and only into the mid 60s Sat.
***FROM PREVIOUS DISCUSSION***
Conditions will be warmer and drier on Sunday as a weak ridge
moves into the region... which is followed by a weak trough on
Monday and a slight chance of light showers. There continue to be
significant differences in the models beyond Monday however...
with the possibility of a stronger ridge over the region or a low
pressure center that drops down to the east of the region. The
second solution provides a possibility of unsettled weather for
Tuesday and Wednesday. Have kept the forecast on the warm and dry
side but this discrepancy will bear watching.
At 2303Z, there was no marine inversion present at KLAX.
Generally hi confidence in the 00Z TAFs. VFR conditions are expected
at all the airfields thru Thu afternoon. There is a slight chance of
thunderstorms around KWJF and KPMD thru about 02Z this evening, with
a 20 percent chance of MVFR conditions. Gusty w to nw winds will
affect several airfields thru this evening, and some airfields Thu
afternoon, including KSBA, KOXR, KCMA, KSMO, KLAX and KLGB. Gusty w
to nw winds will affect KWJF and KPMD thru Thu.
KLAX...Generally hi confidence in the 00Z TAF. VFR conditions are
expected thru Thu evening. Gusty w winds will affect the airfield
thru this evening, and again Thu afternoon and early evening.
KBUR...High confidence in the 00Z TAF with VFR conditions expected
through Thu afternoon.
Gusty NW winds will be at SCA levels tonight through Thursday
across much of the coastal waters. There will be a few gale force
gusts between San Nicolas Island and Santa Rosa Island during
this time. The winds will weaken late Thursday night into Friday.
There is a 60 percent chance SCA winds will affect the outer
coastal waters this weekend.
CA...Beach Hazards Statement in effect through Thursday afternoon
for zones 39>41-87. (See LAXCFWLOX).
PZ...Small Craft Advisory in effect until 3 AM PDT Thursday for
zones 645-650-670. (See LAXMWWLOX).
Small Craft Advisory in effect until 4 PM PDT Thursday for
zone 655. (See LAXMWWLOX).
Small Craft Advisory in effect until 9 PM PDT Thursday for
zones 673-676. (See LAXMWWLOX).
.HAZARD POTENTIAL OUTLOOK...(SAT-WED)
A weak rain event is expected Friday night and Saturday, with
minimal impacts. High surf and strong rip currents are likely
Friday into Sunday.