July 17, 2018
82.3 °F
Heat Idx
84.6 °F
Dew Pt.
65.0 °F
1012.1 hPa 
  rising slowly
3.0 mph 
0.00 in 
  0.00 in/hr
UV index
Solar rad.
100 W/m²

Tonight: Partly cloudy, with a low around 69. South southwest wind 5 to 10 mph.
Partly Cloudy


Wednesday: A 20 percent chance of showers and thunderstorms before 11am.  Mostly sunny, with a high near 93. South southwest wind 5 to 10 mph.
Slight Chance
T-storms then
Mostly Sunny
Lo 69 °F Hi 93 °F
FXUS66 KLOX 180017 AAA

Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
517 PM PDT Tue Jul 17 2018

updated aviation discussion

.SYNOPSIS...17/315 PM.

Temperatures will remain hot across the region for at least another
week though onshore flow will provide some overnight and morning
relief along the coast. There is a slight chance of thunderstorms
Wednesday and Thursday across the Antelope Valley and portions of
Los Angeles, Ventura, and Santa Barbara Counties.


.SHORT TERM (TDY-FRI)...17/139 PM.

Today was a very similar day in most respects, though it is more
humid as monsoon moisture starts to work its way into the area
from the southeast. Getting some small cu over the eastern San
Gabriels but so far very little vertical development and may end
up removing storm chances for this evening unless there`s a
significant increase in buildups.

The forecast for the next couple days remains largely the same.
The increase in moisture will continue through Wednesday with
precipitable waters rising from between 1 and 1.5" today to almost
2" Wednesday. The easterly waves that the models showed coming
through just south of the area later tonight and tomorrow are now
even farther south so that`s not a favorable sign for storm
development at least for coast/valley areas, however models still
indicate enough instability to justify some low precip chances
later tonight into Wednesday morning for lower elevations and
through the afternoon for the mountains and Antelope Valley. The
latter having a better chance of occurring. Given the high PW
content any storms that do form would have the potential for
generating heavy rain, though the 20-25kt steering flow from the
east will keep storms moving along and limit flooding potential.

Lower than usual confidence in the stratus coverage tonight given
the influx of moisture aloft. Better chance of solid coverage
continuing in the north but less so in the south.

Either little change in temps or just slightly cooler temps
Wednesday unless cloud coverage is thicker than anticipated.
Increasing humidity will more than offset any apparent drop in
temperatures. Then turning slightly warmer Thu/Fri.

Moisture starts to decrease Thursday into Friday but weak
instability remains, mainly just over the mountains and AV. If
moisture lingers and we get storms the next couple days then
pops may have to be increased Friday.

.LONG TERM (SAT-TUE)...17/148 PM.

The center of the high will shift a bit east late Friday into
Saturday, which will result in a shift of the flow aloft from
easterly to southerly. Not much impact unless that becomes
favorable for additional moisture advection. Currently the models
keep things pretty dry over the weekend but will have to keep
watching that as we get closer. By Sunday the high starts to shift
back west and that`s when we`ll see temps surging upwards again.
Monday/Tuesday expected to be the warmest of the seven day period,
though it`s not looking much cooler the rest of the week after
that, especially inland. The 06z GFS showed a stronger northerly
push Monday night into Tuesday than the previous runs or the 12z
run showed, which if true would certainly up the ante in terms of
the impacts of this next heat wave with the possibility of
Sundowners and compressional heating. Bumped up highs a few
degrees in most areas Mon/Tue with the idea that there would be
some increase in north flow, though not quite as strong as what we
saw on July 6, and thus not quite as hot either. Even still,
current forecast highs would be enough to justify heat
advisories/warnings across much of the area.



At 2335Z at KLAX, the marine inversion was around 1200 ft deep. The
top of the inversion was around 3600 feet with a temperature near
27 degrees Celsius.

Moderate confidence overall in the 00Z TAFs. Low clouds with
LIFR/IFR/MVFR cigs are expected to move into the coastal airfields
from TAF issuance time at KLAX and KSMO to about 10Z at KSBA and
KCMA. The low clouds will persist thru late Wed morning to early Wed
afternoon before clearing to VFR. The timing of the onset and
dissipation of the low clouds and timing between flight cats may be
off +/- an hour or two.

For KBUR and KVNY, there is generally hi confidence in VFR
conditions thru the TAF period, altho there is a 20% chance low
clouds with IFR/MVFR cigs could move into KBUR late tonight and
early Wed morning.

For KPRB, KPMD and KWJF, there is hi confidence in the 00Z TAFs with
VFR conditions thru Wed afternoon. Gusty south to southwest
afternoon and evening winds will prevail during the TAF period as

There is also a slight chance of high-based thunderstorms Wed
morning for L.A. County and far southern VTU County, and Wed
afternoon for the Antelope Valley, which could affect many airfields
in this area with brief gusty and erratic winds.

KLAX...Moderate confidence overall in the 00Z TAF. Low clouds with
mostly MVFR cigs are expected at the airfield from TAF issuance time
to about 21Z Wed and again aft about 03Z Wed evening. Otherwise, VFR
conditions can be expected. The timing of the onset and dissipation
of the low clouds may be off +/- an hour or two. There will also be
a slight chance of high-based thunderstorms Wed morning which could
bring brief gusty and erratic winds to the airfield.

KBUR...Generally hi confidence overall in the 00Z TAF. VFR
conditions should prevail thru Wed afternoon, altho there is a 20%
chance of low clouds and IFR/MVFR cigs late tonight and early Wed
morning. There is also a slight chance of high-based thunderstorms
Wed morning which could brief gusty and erratic winds to the


.MARINE...17/155 PM.

Small Craft Advisory winds are not forecast across the waters
through Sat. However, there is a 20-30% chance of SCA level
winds across the outer waters this afternoon and evening.

Choppy short period seas will linger across the waters thru Wed.

There is a slight chance of thunderstorms across the southern
waters late tonight through Wed evening.





Warming temperatures expected Sunday through Tuesday with the
possibility of heat advisories and/or warnings.





NWS LOX Office Area Forecast Discussion