Wildfire in California, July 5 to 10, 2020

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
126 PM PDT Sun Jul 5 2020

.SYNOPSIS...05/124 PM.

After a very warm Monday, temperatures will cool Tuesday through
Thursday with a gradual increase in coastal low clouds and fog.
Gusty Sundowner winds will be likely tonight and Monday night.
For Friday through next weekend, building high pressure will
bring a return of heat to the area.

&&

.SHORT TERM (TDY-WED)...05/124 PM.

Overall, 12Z models in good synoptic agreement through the short
term period. At upper levels, broad trough will develop over the
West Coast through Tuesday then ridge will slowly begin to rebuild
over the area on Wednesday. Near the surface, moderate onshore
flow will continue with some northerly offshore gradients the next
couple of nights.

Forecast-wise, main concern in the short term is the winds.
Moderate onshore gradients will generate gusty southwesterly
winds across interior sections each afternoon through Wednesday.
At this time, these southwesterly winds will remain below advisory
levels. Additionally, there is a concern about Sundowner winds
the next couple of evenings. Models indicate SBA-SMX gradient
ranging between -3.0 to -3.5 MB the next three evenings with
marginal upper level support. So, will anticipate some gusty
northerly winds through/below the Santa Ynez Range (especially
west of Goleta), but do not anticipate widespread advisory-level
winds. Also, there will be some gusty northerly winds through the
I-5 Corridor, but these winds will also remain below advisory
levels.

Otherwise, the short term period should be rather benign. Main
challenge will be forecasting extent of marine layer stratus.
Currently, marine inversion is quite shallow (under 1000 feet
deep). Over the next three evenings, will anticipate a slight
deepening of the inversion and a gradual increase in stratus
coverage due to continued onshore gradients and slight lowering of
H5 heights. Any stratus/fog tonight and Monday night should be
confined to the coastal plain (with some dense fog likely) with
stratus pushing into the lower coastal valleys Tuesday night.
Dissipation of stratus each day should be pretty good. Other than
any potential stratus, skies should remain mostly clear.

As for temperatures, today will be the warmest day in the short
term. A cooling trend is anticipated Monday through Wednesday with
most areas falling to around seasonal normals by Wednesday.

.LONG TERM (THU-SUN)...05/124 PM.

For the extended, 12Z models continue to exhibit good synoptic
agreement. At upper levels, high pressure builds near the Four
Corners through the period. Near the surface, weak to moderate
onshore flow will prevail with a bit of northerly offshore
gradients thrown in.

Forecast-wise, a very classic Summertime pattern is on tap for the
area in the extended period. As the upper level high develops near
the Four Corners area, the marine inversion will become more
shallow from day-to-day and the areal extent of stratus/fog will
follow suit each night (with little, if any, stratus by Saturday
and Sunday). Other than any potential stratus, will expect mostly
clear skies through the period. However, will definitely have to
watch exactly where the upper level high develops as some
monsoonal moisture could move into the area this weekend. So, the
mostly clear forecast may need to be adjusted in a few days,
depending on how things develop.

As for temperatures, increasing thicknesses/H5 heights and less
marine influence will bring a warming trend to the area with
Saturday/Sunday likely the warmest days (valleys in the mid to
upper 90s and interior sections in the low 100s). In fact, would
not be surprised to see temperatures actually a little warmer
than currently forecast. Will have to watch the situation closely
over the next few model runs.

&&

.AVIATION...05/1908Z.

At 1730z at KLAX... The inversion was surface based. The top of
the inversion was around 3900 feet with a temperature of about 24
degrees Celsius.

Overall... Moderate to high confidence in the current TAFs. IFR/MVFR
conditions will return to KLAX, KLGB, and KSMO 09z-16z. There is a
less than ten percent chance of IFR/MVFR conditions at KBUR and KVNY
09z-16z. Otherwise and elsewhere, VFR conditions will prevail.

KLAX... Moderate confidence in the current TAF. IFR/MVFR conditions
will return 09z-16z. Otherwise, VFR conditions will prevail throughout
the forecast period. There will not be any east winds greater than
8 kts.

KBUR... High confidence in the current TAF. There is a less than
ten percent chance of IFR/MVFR conditions 09z-16z. Otherwise, VFR
conditions will prevail throughout the forecast period.

&&

.MARINE...05/124 PM.

For the northern and central outer waters zones (PZZ670/673),
Gale force winds. mainly this afternoon thru Mon night. There is
a 25% chance that Gales will continue thru Tue night, but if not,
Small Craft Advisory (SCA) level winds and seas will. SCA level
winds are likely Tue night/Wed. There is a 40% chance of SCA level
winds Thu.

For the southern outer waters zone (PZZ676), SCA level winds and
seas will develop today, then continue thru Tue night, There is a
30% chance of Gale force winds Mon/Mon night, northwest of San
Nicolas Island. There is a 40% chance of SCA level winds Wed thru
Thu.

For the inner waters north of Pt. Sal, SCA level winds will
develop this afternoon and continue into tonight. There will be SCA
level winds during the afternoon and evening hours Mon and Tue.
Otherwise, seas will be at or above SCA thresholds later today
thru Tue evening. There is a 30% chance of SCA conds Wed thru Thu.

For the inner waters south of Pt. Conception, winds and seas will
remain below SCA levels thru Thu. The exception will be in
western Santa Barbara Channel, with SCA level winds likely during
the afternoon thru late night hours today and Mon. There is a
35% chance of SCA conds in western portions of the SBA Channel
during the late afternoon thru late evening hours Tue thru Thu.

Patchy dense fog, with visibility 1NM or less, will affect the
waters south of Pt Conception in the night/morning hours thru Tue.

There will be dangerous seas across much of the waters thru Tue.
There will be a combination of a long period south swell creating
large waves nearshore and hazards to drifting boaters, and a steep
large short period swell.

&&

.BEACHES...05/123 PM.

High surf and strong rip currents will continue through early
Monday on Southern California beaches. A long-period south swell
will peak today at 3 to 4 feet at 17 seconds. High surf of 5 to 8
feet will occur on exposed south and southwest facing beaches of
Los Angeles and Ventura Counties, and 8 to 11 feet on exposed
Central Coast beaches. The Santa Barbara south coast will have
minimal affects from this swell due to blockage from the Channel
Islands, but local sets to 5 feet and hazardous rip currents will
occur near Rincon Point.

The high tides this evening will be quite high, between 6.5 and 7
feet. High tides will be between 10 and 1030 PM PDT this evening.
Within a couple of hours on either side of high tide, there will
likely be minor coastal flooding of beaches and harbor walkways.

Pay attention to beach closures this weekend. In addition to large
surf and dangerous rip currents, dangerous breaking waves from
long period waves, have a history of ocean rescues and drownings.
Stay off the rocks and jetties near the water's edge.

&&

.FIRE WEATHER...05/601 AM.

Hot and dry conditions are expected across interior areas today
and Monday, where humidities in the single digits and teens will
be common. The driest air will be focused across the Antelope
Valley, mountains, and interior valleys of SLO County where
humidities as low as 5 percent can be expected. In addition,
locally gusty southwest to northwest winds (gusting between 25 and
40 mph) will continue across interior sections, strongest in the
Antelope Valley. Warm and dry conditions are also expected to
linger through the nighttime hours in the foothills and mountains.
The combination of hot temperatures, low humidities, locally
gusty winds, and drying fuels will bring elevated fire weather
conditions to interior areas today through Monday.

Elevated fire weather conditions are also expected today into
Monday across the western portions of the Santa Barbara south
coast and adjacent foothills, mainly late afternoon and evening
hours. These areas can expect gusty sundowner winds, mainly from
Gaviota to San Marcos Pass where wind gusts of 35 to 45 mph will
be common. The sundowner wind conditions will also bring warm and
dry conditions, with humidities lowering into the teens and 20's
across foothill areas, while temperatures climb to around 90
degrees.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...High Surf Advisory in effect until noon PDT Monday for zones
      34-35-40-41-87. (See LAXCFWLOX).
PZ...Small Craft Advisory in effect until 3 AM PDT Wednesday for
      zones 645-676. (See LAXMWWLOX).
     Small Craft Advisory in effect until 3 AM PDT Monday for zone
      650. (See LAXMWWLOX).
     Gale Warning in effect until 3 AM PDT Tuesday for zones
      670-673. (See LAXMWWLOX).

&&

.HAZARD POTENTIAL OUTLOOK (WED-SUN).

No significant hazards expected.

&&

PUBLIC...Thompson
AVIATION...Kj
MARINE...DB/Kj
BEACHES...DB/Kj
FIRE...Gomberg/Kaplan
SYNOPSIS...RAT

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