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FXUS66 KLOX 191022

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA 
322 AM PDT Fri Oct 19 2018

.SYNOPSIS...19/307 AM.

Locally moderate offshore winds, with warm and dry conditions are
expected through Saturday. This will bring fire weather danger to
some areas in Los Angeles and Ventura Counties through at least 
this evening. Above normal temperatures will continue through the 
weekend, with better cooling expected early next week. A slight 
chance of showers across the Ventura County Mountains Sunday 
afternoon. The cooling trend should continue early next week with 
increasing night through morning low clouds for mainly coastal 


.SHORT TERM (TDY-SUN)...19/301 AM.

Latest fog product imagery indicated skies were mostly clear,
except patchy low clouds around Lompoc and Vandenberg AFB. Since 
there is weak offshore flow across much of the Central Coast, 
figure that the low clouds and fog will scour out rather quickly 
this morning. LAX-DAG offshore gradients were around -3.5mb this 
morning and should strengthen to just over -4 mb by daybreak. The 
24-hour trend was about 1.5mb stronger than yesterday at this 
time. This is strictly a surface gradient driven offshore wind
event with no upper support. Therefore, with gradients trending
slightly stronger offshore,expect slightly stronger Santa Ana 
winds compared to yesterday morning. Still,winds are expected to 
remain below wind advisory thresholds. There could be local gusts 
between 35 and 40 mph in a few wind prone passes and canyons of 
the valleys/mountains this morning. The combination of the
offshore flow and slightly higher H5 heights and boundary layer
temps, high temps should bump up 2 to 6 degrees, while the Central
Coast should be 6 to 12 degrees warmer with highs reaching the mid
80s in many Central Coast locations. 

Where the winds are not blowing, a very dry airmass with clear 
skies will result in good radiational cooling in sheltered areas 
again tonight into Sat morning. Temps are expected to drop into 
the mid 30s to low 40s in the interior SLO County vlys, and low 
40s with the possibility of upper 30s in the Ojai Vly by late 

Not much change expected for Saturday, except slightly less wind
forecasted as the LAX-DAG surface gradients weaken but remain
offshore all day. High temps should moderate cooler a degree or
two in most areas. Could be more cooling across the Central by
Saturday afternoon as the Seabreeze kicks in earlier. 

By Sunday, gradients turn onshore and an upper level trough
develops. This will bring several degrees of cooling to coastal 
areas and somewhat cooler across inland areas as well, but not as
much. Models were hinting at some instability across the local
mountains with a pool of moisture across the Ventura County
Mountains and NE into the Tehachapi Mtns and Sierras. Have added 
a slight chance for thunderstorms for the Ventura County Mtns 
Sunday afternoon, but have kept them out of the San Gabriel Mtns 
at this time as soundings were not as impressive with moisture and
some capping aloft. If showers or thunderstorms do occur Sunday 
afternoon, they should be short lived as PWAT values will be under
an inch, although showers will be slowly moving slowly.

.LONG TERM (MON-THU)...19/317 AM.

Both the GFS and ECMWF models look to be in good agreement with 
large scale features early next week through Thursday. The 
cooling trend will continue through Wednesday as a broad upper 
trough lingers across the area. Temperatures should lower down to 
more seasonal normals. The European model is slightly quicker in 
nudging an upper level ridge from the Eastern Pac over SoCal by 
Thu, but the GFS matches up nicely on Friday with a strong 590 DM 
high sitting off the coast. Expect high temps to climb late this 
week, especially on Friday. Surface gradients show another 
offshore flow developing. Too soon to say how strong, but as of 
now, does not look anything strong as not picking up on any cold 
air settling into the Great Basin.



At 2315Z at KLAX, there was a near surface-based inversion. The 
top of the inversion was around 700 ft deep with a temperature of
24 deg C.

High confidence in the 00z TAFs. Except for a 30%-40% chance of 
LIFR conditions at KSMX and KSBP late tonight into Fri morning, 
all airfields will have VFR conditions thru Fri afternoon. 
Increasing offshore flow can also be expected with gusty N to NE 
winds expected at KVNY, KWJF and KPMD late Fri morning thru the 
KLAX...High confidence in VFR conditions through the period.

KBUR...High confidence in VFR conditions through the period.


.MARINE...19/321 AM.

For the outer waters, High confidence that winds will remain below
Small Craft Advisory (SCA) level thru this weekend. There is a 
20% chance of local SCA level N-NE wind gusts across the 
southern zone (PZZ676) this morning, mainly in eastern portions. 
There is a 30-40% chance of SCA level NW winds across the outer 
waters Mon thru Tue, except SCA level winds are likely during that
time across the northern outer waters zone (PZZ670).

Across the inner waters n of Point Conception, winds should 
remain below SCA levels thru this weekend, then there is a chance
of SCA level winds Mon, and SCA level NW winds are expected Tue.

For the coastal waters S of Point Conception, winds should remain
below SCA levels thru Tue, except there will be a 40% chance of
SCA level NW winds this morning from Pt. Mugu to Santa Monica, 
and less likely across the San Pedro Channel.


CA...Red Flag Warning in effect until 10 PM PDT this evening for
      zones 240-241-244>246-253-254-288-547-548. (See LAXRFWLOX).



No significant hazards expected.




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