Rowland Heights, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

513
FXUS66 KLOX 272209
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
209 PM PST Fri Dec 27 2024

.SYNOPSIS...27/1247 PM.

A prolonged period of gusty northerly winds is expected through
early next week, then transitioning to a moderate Santa Ana event
on New Years Day through the end of next week. Warmer
temperatures are expected Saturday, then cooling Sunday as a weak
system moves through with some light rain possible along the
Central Coast. Much warmer temperatures are expected for coast and
valleys by the middle of next week with the Santa Ana winds.

&&

.SHORT TERM (TDY-MON)...27/132 PM.

A weak weather system moved through the area this morning and
managed to hold together long enough to drop some drizzle and
light rain as far south as Long Beach. Amounts across LA/Ventura
Counties were generally a trace to .03", except as much as
.05-.07" from Thousand Oaks to Calabasas. Most of the light precip
is ending now as downsloping and drying northwest flow aloft re-
establishes.

Going forward, the primary theme over the coming days will be a
prolonged period of moderate to occasionally strong north to
northwest winds, strongest across the Santa Ynez Range, the
Antelope Valley, and throughout much of the Transverse range. And
at times winds will filter down into some of the valleys and
possibly even down into west LA as well. Wind advisories are
currently in effect for a lot of those areas through tonight but
additional advisories and possibly low end high wind warnings may
be needed at times through the middle of next week. Most areas
Saturday will experience 3-6 degrees of warming, but especially
the coastal valleys south of Pt Conception.

There is one last very weak weather system later Sunday that may
drop some very light rain mainly just for northwest SLO County and
possibly the Grapevine region. But the bigger impact will be to
inject additional northwest flow aloft that will maintain gusty
winds in those same areas through at least Monday.

Overall, there should be less morning low clouds and fog with the
predominant northwest flow in place, but there still may be some
patchy clouds and fog, especially across coastal LA county and
some radiation fog in the mornings following any precipitation.

.LONG TERM (TUE-FRI)...27/154 PM.

Strong northerly flow will continue Tuesday and actually begin to
transition to a Santa Ana Tuesday night into Wednesday as a trough
follows the typical path through the Pac NW and down through the
Great Basin. This creates rapidly rising surface pressures across
Nevada which then turns into Santa Ana winds funneling through the
Highway 14 corridor and into the northwestern LA County and
southern Ventura County. Models have been fairly consistent
indicating the preceding north wind event will be stronger than
the Santa Anas, but even still with the northeast gradient
reaching anywhere from 5-6 mb and some support aloft we can expect
to see at least advisory level Santa Ana winds in the usual
favored areas (not in Pasadena) with warming temperatures across
coast and coastal valleys and lowering humidities. Across interior
areas though, including the Antelope Valley, the mountains, and
interior SLO County, temperatures will be several degrees cooler
due to the absence of any downslope warming processes. Overnight
night temperatures will be quite chilly as well with some sub-
freezing temperatures likely.

New Years Day should be the peak of the Santa Ana`s, however a
weak to moderate offshore flow with decreasing support aloft will
continue into Thursday and even possibly Friday as well. And
longer range ensemble solutions continue to offer few if any
signs for additional rain through at least the middle of January.

&&

.AVIATION...27/1807Z.

At 17Z at KLAX, there was no marine inversion present.

Overall, moderate confidence at best in the 18Z TAFs. Most coast
and vly airfields are expected to have MVFR/IFR conds thru much of
the fcst period, and even VLIFR conds (50% chance) later tonight
into early Sat at KPRB and KSBP. The timing of the changes in
flight cats may be off +/- 1 to 3 hours.

Strong and gusty SW to W winds will affect KPMD and KWJF thru
this evening. MVFR vsbys due to blowing dust will be possible
(50% chance) this afternoon at KWJF.

KLAX...Moderate confidence at best in the 18Z TAF. MVFR/IFR/LIFR
conds are expected thru about 17Z Sat. Changes in flight cats may
be off +/- 1 to 3 hours. There is also a 30% chance that IFR/LIFR
conds may not occur or be short-lived. There is a 30% chance of an
east wind component of 6-8 kt until 20Z and also 17Z-20Z Sat.

.KBUR..Moderate confidence in the 18Z TAF. MVFR cigs are expected
until about 03Z this evening followed by VFR conds thru the rest
of the fcst period. The timing of flight cat changes may be off
+/- an hour or two.

&&

.MARINE...27/111 PM.

For the outer waters, there is generally hi confidence in the
current forecast. A series of large westerly swells will continue
to move into the waters for the next several days. Winds and/or
seas will be at Small Craft Advisory (SCA) levels through Mon
night. There is a 50% chance that SCA level wind gusts could
continue Tue and Tue night, then conds will be below SCA levels
Wed and Wed night.

For the inner waters north of Point Sal, there is generally hi
confidence in the current forecast. A series of large westerly
swells will continue to move into the waters for the next several
days. Seas will be at SCA levels through Monday afternoon. Gusty
winds to around SCA levels will be possible Mon afternoon and
possible into the evening (40% chance). There is also a 30% chance
of SCA wind gusts at times Sat afternoon and evening. Winds and
seas should then be below SCA levels Mon night through Wed night,
except for a 30% chance of SCA gusts at times Tue afternoon and
evening.

For the inner waters south of Point Conception, there is
generally hi confidence in the current forecast. For the Santa
Barbara Channel, winds and/or seas will be at SCA levels through
Mon afternoon, then conds should be below SCA levels Mon night
thru Wed night. For the southern inner waters, seas will be above
SCA levels thru tonight, then conds should largely remain below
SCA levels Sat through Wed night.

&&

.BEACHES...27/110 PM.

A series of large and long period west to northwest swells will
bring high surf to the west-facing beaches of the Central Coast
and the Ventura County and Los Angeles County beaches thru early
next week. Above normal surf is also expected on west-facing
beaches of the south Santa Barbara County coast through Sun
evening.

Surf of 10 to 15 ft is expected much of the time thru Sun morning
on Central Coast beaches. The surf there should diminish some to
8 to 11 feet Sunday afternoon and continue into Mon night.

For the VTU County beaches, surf of 6 to 10 ft is expected
through Sun then lower to around 5 to 7 feet Sun night and
continue through Mon evening.

On west-facing beaches of L.A. County, surf of 5 to 8 feet can be
expected through Sun night.

On west-facing beaches of the south coast of SBA County, elevated
surf of 3 to 6 ft is expected thru the weekend. Local max sets to
7 feet will be possible on well-exposed west-facing shores.

Nuisance to minor coastal flooding may continue to affect beaches
on the Central Coast and the Ventura County/L.A. County Coast
around the time of the early morning high tides thru the weekend.
Please reference our SRF and CFW products for details.

&&

.FIRE WEATHER...27/201 PM.

***FIRE WEATHER WATCH IN EFFECT FROM TUESDAY MORNING THROUGH
 THURSDAY EVENING FOR GUSTY SANTA ANA WINDS AND LOW RELATIVE
 HUMIDITY FOR MUCH OF CENTRAL/WEST-CENTRAL/SOUTHWEST LOS ANGELES
 COUNTY AND CENTRAL/EAST-CENTRAL/SOUTHERN VENTURA COUNTY***

For this weekend, north-wind-prone locations could experience elevated
to briefly critical fire-weather conditions from the Santa Barbara
County mountains to the high terrain of northwest Los Angeles County
surrounding the Interstate-5 corridor. Locally enhanced sundowner winds
will focus such potential over the Santa Ynez Range. However, humidities
will remain elevated in most areas while the strong-wind risk remains
localized, precluding fire-weather headlines through this weekend.

Confidence continues increasing that the weather pattern next week will
become favorable for elevated to critical fire-weather conditions
across Santa Ana wind-prone areas of Los Angeles and Ventura Counties,
as well as portions of Santa Barbara County prone to north-wind
enhancements. Next week, an upper-level ridge is forecast to gradually
build along the Pacific coast to the west of a large upper trough
encompassing much of the central and eastern states. Correspondingly,
surface high pressure strengthening over the Great Basin will facilitate
increasing offshore flow amid slight to moderate upper support, which
will combine with unseasonably warm temperatures assisted by the
building upper ridge to produce the increased fire-weather risk. LAX-
Bakersfield offshore gradients are currently forecast to reach 5-7 mb
starting Monday, with LAX-Daggett offshore gradients reaching 4-5 mb
starting Tuesday. Given the enhanced northerly pressure gradients, wind
directions could be 10-20 degrees more northerly than easterly for this
event compared to other November and December 2024 events, especially
early on for this next event.

The greatest potential for critical fire-weather conditions will include
areas prone to a moderate Santa Ana wind event, for Tuesday through
next Thursday. This includes much of Central/West-Central/Southwest Los
Angeles County and Central/East-Central/Southern Ventura County.
Strengthening consensus among weather-model solutions regarding the
pattern favoring critical fire-weather conditions has warranted the
issuance of the Fire Weather Watch.

Regarding alternate scenarios, there is a 60% chance for fire-weather
headlines to be expanded to include the eastern San Gabriels, northwest
Los Angeles County Interstate-5 corridor, and northern Ventura County
mountains. In addition, the enhanced northerly gradients may tend to
expand the fire-weather risk to the east of areas more typically prone
to a moderate Santa Ana wind event, to also include areas from Hollywood
to Beverly Hills and Santa Monica -- Confidence: lower chance at 40%
for fire-weather headlines. Elevated to brief critical fire-weather
conditions will also be a concern farther west across the Santa
Barbara County mountains and especially the Santa Ynez range when
northerly pressure gradients are strongest on Monday and Tuesday,
though humidities will likely remain elevated -- Confidence:
even smaller but non-zero chance at 20% for fire-weather headlines.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory remains in effect until 10 AM PST Saturday for
      zones 88-349-351>353-376>380. (See LAXNPWLOX).
     High Surf Advisory in effect until 3 AM PST Tuesday for zones
      340-346. (See LAXCFWLOX).
     Beach Hazards Statement in effect through Sunday evening for
      zones 349-350. (See LAXCFWLOX).
     High Surf Advisory in effect until 9 PM PST Monday for zone
      354. (See LAXCFWLOX).
     High Surf Advisory in effect until 3 AM PST Monday for zones
      362-366. (See LAXCFWLOX).
     Wind Advisory remains in effect until 4 AM PST Saturday for
      zones 381>383. (See LAXNPWLOX).
     Fire Weather Watch in effect from Tuesday morning through
      Thursday evening for zones
      288-354-355-358-362-369>372-374>376-379. (See LAXRFWLOX).
PZ...Small Craft Advisory in effect until 3 PM PST Monday for
      zones 645-650. (See LAXMWWLOX).
     Small Craft Advisory in effect until 3 AM PST Saturday for
      zone 655. (See LAXMWWLOX).
     Small Craft Advisory in effect until 3 AM PST Tuesday for
      zones 670-673-676. (See LAXMWWLOX).

&&

$$

PUBLIC...MW
AVIATION...Sirard
MARINE...Sirard
BEACHES...Sirard
FIRE...Cohen
SYNOPSIS...MW

weather.gov/losangeles

Experimental Graphical Hazardous Weather Outlook at:
https://www.weather.gov/erh/ghwo?wfo=lox