October 17, 2018 Fire Weather Watch - Los Angeles County San Gabriel Valley (California)
Temp
 
82.2 °F
 
Dew Pt.
 
39.5 °F
 
Humidity
 
22%
 
Pressure
 
1014.3 hPa 
  falling slowly
Wind
 
4.0 mph 
    WSW
Rain
 
0.00 in 
  0.00 in/hr
UV index
 
---  
 
Solar rad.
 
100 W/m²
 
Tonight

Tonight: Clear, with a low around 58. West southwest wind 5 to 10 mph becoming east northeast in the evening.
Clear
Thursday

Thursday: Sunny, with a high near 89. North northeast wind around 5 mph becoming south in the afternoon.
Sunny
Lo 58 °F Hi 89 °F
000
FXUS66 KLOX 172054
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
154 PM PDT Wed Oct 17 2018

.SYNOPSIS...17/811 AM.

High pressure and weak offshore flow will keep high temperatures
above normal through the week. The weekend continues warm and
looks to bring a little more offshore winds by Saturday. Monday
is expected to be cooler with the arrival of a weak trough of low
pressure.

&&

.SHORT TERM (TDY-SAT)...17/142 PM.

So Cal is currently between an upper low near the Grand Canyon and
an eastern Pacific ridge. Not really much change in this through
Thursday. Air mass will warm slightly as the rest of that cold
air from the previous system shifts east and warmer air from the
ridge moves in. So most areas should see a degree or two of
warming Thu. On Friday offshore flow strengthens and while
forecast gradients remain about the same or even slightly weaker
than earlier model runs the support aloft has increased by around
10 kt. So this pushes wind speeds closer to the advisory level
Friday, though it`s probably mostly a sub-advisory event still in
most locations. Gradients actually a little stronger Saturday but
upper support is weaker so that typically means less widespread
winds and generally a little lighter. Temps Friday will get a
boost with the increase in offshore flow with highs getting close
to 90 at lower elevations then a degree or two warmer Saturday.

The GFS has trended drier Sat and more in line with the ECMWF so
precip has been removed from the forecast, though it`s not a zero
chance.

.LONG TERM (SUN-WED)...17/151 PM.

The upper low over central CA will slowly move east early next
week with gradients turning weakly onshore by Sunday afternoon.
This will initiate a cooling trend area-wide but more so closer to
the coast. May see a few mid and high clouds across the eastern
portion of the forecast area but otherwise pretty clear. By
Monday and Tuesday highs should be very close to seasonal norms
with some marine layer clouds possible by Tue. Models diverge
somewhat after Tuesday with the GFS still favoring a faster return
of the eastern Pacific ridge while the ECMWF shows another trough
hitting the Pac NW and preventing heights from rising much. More
of the GEFS ensemble members are supporting the ECMWF solution so
kept temps Wed pretty close to Tue, though the operational GFS
would certainly support more of a warm up.

&&

.AVIATION...17/1800Z.

At 1800Z, there was no marine layer at KLAX.

High confidence in the current forecast. There is a chance of LIFR
conditions at Central Coast terminals later tonight, otherwise
VFR conditions are expected throughout the period.

KLAX...VFR conditions are expected throughout the period. Any
easterly winds are expected to remain less than 7 knots.

KBUR...VFR conditions are expected through the period. No wind
impacts are expected at this time.

&&

.MARINE...17/145 PM.

High confidence in winds and seas remaining below Small Craft
Advisory levels through Friday. There is a 40 percent chance of
gusty northeast winds developing across the inner waters between
Friday and Saturday. There is a 30 percent chance of advisory
levels winds northwest of the Channel Islands Friday afternoon and
night.

&&

.FIRE WEATHER...17/146 PM.

Offshore winds will increase on Friday and continue through
Saturday. These wind gusts will NOT be nearly as strong as what
occurred earlier this week (50 to 75 mph), but gusts between 30
and 45 mph are possible. The moderately dry conditions currently
occurring will change little through Saturday, with minimum
humidities generally between 10 and 20 percent at lower
elevations. As a result, along with little to no improvement in
fuel conditions leading up to Friday, marginally critical
conditions are possible over much of Los Angeles and Ventura
Counties. This event will not nearly be as severe as what occurred
on Monday and Tuesday, but a Red Flag Warning may still be
warranted. This watch will either be converted to a Red Flag
Warning or canceled on Thursday.

There will be easterly winds (gusts of 20 to 30 mph) and
marginally dry conditions over Santa Barbara and San Luis Obispo
Counties as well, but the winds will be weaker than their
neighbors to the south. Elevated fire conditions will persist
there, but conditions should stay below Red Flag thresholds.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Fire Weather Watch in effect from late Thursday night through
      Saturday afternoon for zones
      240-241-244>246-253-254-288-547-548. (See LAXRFWLOX).
PZ...NONE.

&&

.HAZARD POTENTIAL OUTLOOK (SAT-WED).

Elevated to locally critical fire weather conditions expected
Saturday with locally gusty offshore winds, low humidities, warm
temperatures, and dry fuels.

&&

$$

PUBLIC...MW
AVIATION...Sweet
MARINE...Sweet
FIRE...Kittell
SYNOPSIS...B

weather.gov/losangeles

NWS LOX Office Area Forecast Discussion