July 15, 2019 Heat Advisory - Los Angeles County San Gabriel Valley (California)
Temp
 
97.9 °F
 
Heat Idx
 
101.8 °F
 
Dew Pt.
 
63.8 °F
 
Humidity
 
33%
 
Pressure
 
1008.9 hPa 
  falling slowly
Wind
 
3.0 mph 
    W
Rain
 
0.00 in 
  0.00 in/hr
UV index
 
---  
 
Solar rad.
 
100 W/m²
 
This
Afternoon
This Afternoon: Sunny and hot, with a high near 100. Southwest wind around 10 mph.
Hot
Tonight

Tonight: Clear, with a low around 64. Southwest wind 5 to 10 mph becoming light and variable  in the evening.
Clear
Hi 100 °F Lo 64 °F
000
FXUS66 KLOX 152349
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
449 PM PDT Mon Jul 15 2019

.SYNOPSIS...15/133 PM.

Gusty northwest winds will affect southern Santa Barbara County
and the Interstate 5 Corridor later today and tonight. An upper
trough will bring gradual cooling on Tuesday through Sunday.
Night through morning low clouds will be widespread in coastal
and valley areas by midweek.

&&

.SHORT TERM (TDY-THU)...15/138 PM.

The primary weather concern for the next 12-24 hours is the
developing Sundowner event across southern SB County. Pressure
gradients are primed to jump later this afternoon and increasing
northerly flow aloft and subsidence will help drive those winds
down to the coast, mainly from San Marcos Pass and Goleta west to
Pt Conception. Temperatures in the western portion of the Santa
Ynez Range are currently in the 90s and humidities in the teens
and that hot, dry air along with gusty northerly winds 40-50 mph
will surface at lower elevations as the event unfolds this
evening.

Elsewhere, another hot day inland with highs in the 90s to lower
100s while coastal areas are much cooler with the marine layer
hugging the coast south of Pt Conception. As the Sundowners kick
in later this afternoon the marine layer will dissipate west of
of LA County, but overnight low clouds and dense fog will fill in
along the Central Coast. Marine layer depth expected to remain
around 1000` or less.

Gradients trend onshore Tuesday afternoon which should lead to a
couple degrees of cooling across interior areas. Northerly flow is
weaker as well so while gusty winds are expected again across the
Santa Ynez Range they won`t be as strong and temperatures won`t be
quite as warm as today`s event.

Stronger onshore trends expected Wed/Thu resulting in a deeper
marine layer and daytime temps dropping 4-8 degrees on average
from Tuesday`s levels.

.LONG TERM (FRI-MON)...15/144 PM.

Quiet weather pattern anticipated for the latter half of the week
into early next week. The cooling trend that will begin the middle
of this week will continue at a slower pace through Saturday as a
weak upper level trough sits along the west coast while the high
currently over the area shifts well to the east. Daytime highs
will be several degrees below normal with a deeper than usual
marine layer.

Those trends reverse Sunday as the trough weakens and high
pressure rebuilds from the east. Temps will bounce back to normal
by Monday and possibly back up to several degrees above normal by
the middle next week if current models solutions hold.

&&

.AVIATION...15/2349Z.

At 2310Z, the marine layer depth was 1100 feet. The top of the
inversion was 2200 feet with a temperature of 30 degrees Celsius.

N of Point Conception...Low confidence for coastal TAF sites with LIFR/IFR
conds. Mainly after 09z-10z. 40% chance no CIG but some MVFR
Vsbys issues overnight night into Tue morning. High confidence for
CAVU conds at KPRB.

S of Point Conception... Moderate confidence with continued
persistence forecast of IFR Cigs for Coastal TAFS in LA County.
There is a 30% chance for LIFR/IFR Cigs for OXR after 10z. 20%
chance for LIFR/IFR Cigs at KSBA after 12z.
KLAX...Moderate confidence in 06Z TAF. There is a 40% chance that
IFR conds will continue between 05-08z. After 08z, still moderate
confidence for LIFR/IFR Conds through 16z. Higher confidence for
VFR conds after 18z Tue.

KBUR...High confidence in 00Z TAF for CAVU conds through the
24-hour period.

&&

.MARINE...15/129 PM.

For the Outer Waters, moderate confidence in current forecast.
The forecast models continue to deliver a strong argument for GALE
FORCE winds for much of this afternoon through tonight, so a GALE
WARNING has been issued for all outer waters through 10z. The GALE
FORCE winds may return again on Tuesday afternoon through Tuesday
night, but the forecast speeds for Tuesday are not as strong as
today.

For the Inner Waters north of Point Sal, moderate confidence in
current forecast. The SCA level winds for today have been extended
through late tonight and there is a 70 percent chance of SCA
level winds Tuesday afternoon and evening. For Wednesday through
Friday, winds and seas are expected to remain below SCA levels.

For the Inner Waters south of Point Conception, moderate to high
confidence in current forecast. For the western half of the Santa
Barbara Channel, there is a 70% chance of SCA level winds late
this afternoon and tonight and a 60% chance of SCA level winds
late Tuesday afternoon and Tuesday night. Otherwise, winds and
seas are expected to remain below SCA levels through Friday.

&&

.FIRE WEATHER...15/235 PM.

Interior areas will continue to see elevated to brief critical
fire weather conditions through Tuesday due to gusty onshore
winds combined with very warm and dry conditions. Minimum
humidities will continue to be in the teens across interior areas
through Tuesday, except locally into single digits across the
Antelope Valley and Los Angeles county mountains. West to
northwest winds gusting between 25 and 35 mph will be common
through Tuesday morning across interior sections, shifting to the
southwest by Tuesday afternoon, with the strongest winds across
the Antelope Valley and Interstate 5 corridor. Triple digit heat
has occurred today across portions of the Los Angeles county
valleys, mountains, and Antelope Valley, with just a few degrees
of cooling on Tuesday.

An even more significant fire weather threat will occur across the
Santa Barbara south coast and Santa Ynez mountains through
tonight as gusty sundowner winds spread from west to east,
increasing late this afternoon into tonight. The current Santa
Barbara-Santa Maria pressure gradient is at -1.6 mb as of 2 pm,
projected to be around -4.5 mb by this evening. Already seeing
some northerly winds gusting between 20 and 30 mph in the hills
above Gaviota and Refugio early this afternoon, with temperatures
soaring into the lower to mid 90s. The strongest sundowner winds
will be focused across the western portions of the south coast
(from Gaviota to Goleta) and Santa Ynez mountains this evening,
where gusts between 40 and 50 mph are expected. Foothill and wind
prone coastal areas will see significant warming and drying
through this evening, with temperatures climbing into the 90s, and
humidities falling to between 12 and 25 percent. The gusty
sundowner winds combined with the very warm and dry conditions
will bring elevated to brief critical fire weather conditions
through tonight across the Santa Barbara south coast and Santa
Ynez mountains. A Red Flag Warning has not been issued yet for
this event as it does not appear that sufficient duration of Red
Flag conditions will occur, but this will be monitored closely
through the evening hours.

Stronger onshore flow combined with increasing marine layer depth
will bring a cooling trend Wednesday into the weekend. The
highway 14 corridor from Santa Clarita Valley to the Antelope
Valley will continue to have elevated fire weather conditions
through the week due to the strengthening onshore winds and
relatively dry conditions.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory in effect until 4 AM PDT Tuesday for zones
      39-52. (See LAXNPWLOX).
     Heat Advisory in effect until 8 PM PDT this evening for zones
      46-88-547. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect until 3 AM PDT Tuesday for
      zones 645-650. (See LAXMWWLOX).
     Gale Warning in effect until 3 AM PDT Tuesday for zones
      670-673-676. (See LAXMWWLOX).

&&

.HAZARD POTENTIAL OUTLOOK (THU-MON).

No significant hazards expected.

&&

$$

PUBLIC...MW
AVIATION...Kaplan
MARINE...Sweet
FIRE...Gomberg
SYNOPSIS...DB/B

weather.gov/losangeles

NWS LOX Office Area Forecast Discussion