Area Forecast Discussion
Issued by NWS Los Angeles, CA

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000
FXUS66 KLOX 101022
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
322 AM PDT Fri Apr 10 2020

.SYNOPSIS...10/100 AM.

The showers will mostly be confined to LA and portions of Ventura
county today. Snow will fall above 5000 feet. The showers will
diminish this afternoon and end tonight. Maximum temperatures
will be well below normal today. It will be dry with a slight
warming trend for the weekend.

&&

.SHORT TERM (TDY-SUN)...10/212 AM.

This is the last day of the never ending low. It is currently
centered over Anacapa Island and is about 554 DM deep. It is
forecast by all mdls to move to the SE and wind up over SAN by
late afternoon. The current position and its forecast track places
Orange and SAN counties squarely in the high rainfall crosshairs.
Much lighter rain embedded in the easterly flow around the low
will fall over LA county and to a lesser degree VTA county. There
will be no more rain for SLO and all but the far eastern portion
of SBA counties. The eastern San Gabriel mtns and the San Gabriel
Vly could still see an additional three quarters of an inch of
rain but almost all areas will only see a tenth of an inch of
extra rain. The wrap around flow will bring continued moderate
snow fall to the eastern San Gabriels with lesser amounts in the
mtns to the west. The winter weather advisory for the VTA mtns
expires at 11am and that looks good. The winter storm warning for
the LA mtns (which is really just for the eastern San Gabriels)
goes until 800 pm tonight and given the wrap around flow that time
seems good also. There will be some sunshine today away from LA
county and max temps will rise into the mid 60s for most coast and
vly locations which is below normal but not anything like the low
values of ydys max temps (Burbank`s max temp of 52 degrees was,
for example, 20 degrees blo normal and was only three degrees
warmer than its normal overnight low)

Any lingering showers over eastern LA county will end this evening
and there will be a return to more normal April weather. A marine
layer stratus deck will likely develop over the waters and some of
the coasts due to the residual moisture and onshore flow.

Northerly slightly anticyclonic flow will set up over the area on
Saturday aside from any morning stratus is will be a mostly sunny
to partly cloudy day. The higher hgts will allow max temps will
rise 1 to 3 degrees and will approach normals. Most coastal and
vly sites will see max temps in the mid to upper 60s with one or 2
70 degree readings thrown in.

On Saturday night the upper flow will become more cyclonic and
more importantly there will be a huge jump in the onshore flow.
Together these two items will produce a very deep marine layer and
low clouds will extend from the beaches to the coastal slopes.
There might be some drizzle as well esp near the foothills. Its
likely there will not be much clearing as the very deep marine
layer will likely cook up into strata cu deck covering more than
half of the sky. The axis of a very weak trof grazes the eastern
side of LA county - enough ensemble members support the idea of a
few showers to warrant a slight chc of showers over the eastern
San Gabriels during the afternoon and early evening. The deep
marine layer and increased onshore flow will bring about 3 to 6
degrees of cooling across the coasts and vlys.

.LONG TERM (MON-THU)...10/320 AM.

California will be on the west end of a CONUS spanning trof Monday
through Wednesday. The state will be under dry slightly cyclonic
NW flow. There moderate onshore flow will likely bring another
deep night through morning stratus deck to the coasts and vlys.
Offshore trends will reduce or eliminate the marine layer clouds
Tue and Wed. Max temps will not change much from Sun on Mon but
will warm substantially on Tuesday and them even more on
Wednesday. Many max temps will be above normal on Tuesday breaking
the 13 day streak of below normal temps. Wednesday will be the
warmest day of the next 7 with max temps 3 to 6 degrees above
normal and chc of a couple 80 degree readings in the vlys.

Onshore flow strengths again on Thursday and this will lead to 3
to 6 degrees of cooling.

Both the GFS and EC show another upper low moving into the area
next Friday but neither is too bullish on any precip chcs assoc
with the low.

&&

.AVIATION...10/0620Z.

At 06Z at KLAX...there was no marine layer or inversion.

Moderate to high confidence in 06Z TAFs north of Point
Conception. Conditions will likely remain dry through the period.
Good confidence in VFR conditions, but with a moist atmosphere and
calm winds, there is a chance of fog developing with IFR/LIFR
conditions possible overnight (especially for KPRB).

Low to moderate confidence in 06Z TAFs south of Point Conception. -RA
will continue overnight and taper off from north to south by late
this morning or afternoon. Low confidence on the ending time for
rain. Moderate confidence in conditions remaining dominantly VFR
overall, but conditions will likely bounce into MVFR periodically.
There is a 20-30% chance of brief IFR conditions in heavier
showers.

KLAX...Moderate confidence in 06Z TAF. -RA likely to continue
through at least 20Z. Cigs will likely bounce between VFR and MVFR
during rain. Low confidence in timing of those fluctuations, with
a 20% chance of occasional IFR with any heavier RA. East winds up
to 9 kt are likely through 18Z, with a 40% chance they will be 10
kt or more.

KBUR...Moderate confidence in 06Z TAF. -RA likely to continue
through at least 19Z. Cigs will likely bounce between VFR and MVFR
during rain. Low confidence in timing of those fluctuations, with
a 20% chance of occasional IFR with any heavier RA.

&&

.MARINE...10/305 AM.

Gusty east to southeast winds will continue over much of the
coastal waters through this morning. There is a chance that gusts
could exceed Small Craft Advisory (SCA) level at times in some
locations south of Point Conception, especially over the SBA
Channel and the Santa Monica Basin.

Gusty NW winds are expected to fill in behind the storm system
this afternoon. There is a 70 percent chance of SCA level winds
this evening through Sunday over the outer waters off the Central
Coast to San Nicolas Island. SCA winds could return Sunday night
and persist through the middle of next week.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Winter Weather Advisory in effect until 11 AM PDT this
      morning for zone 53. (See LAXWSWLOX).
     Winter Storm Warning in effect until 8 PM PDT this evening
      for zone 54. (See LAXWSWLOX).
PZ...Small Craft Advisory in effect from 3 PM this afternoon to 3
      AM PDT Sunday for zones 670-673-676. (See LAXMWWLOX).

&&

.HAZARD POTENTIAL OUTLOOK (SUN-THU).

No significant hazards expected.

&&

$$

PUBLIC...Rorke
AVIATION...Stewart
MARINE...Stewart
SYNOPSIS...30

weather.gov/losangeles


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