Area Forecast Discussion
Issued by NWS Los Angeles, CA
FXUS66 KLOX 032321 AAA
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
420 PM PDT TUE MAY 3 2016
The overnight marine layer will form early Wednesday. Then
a low should arrive by late Wednesday for a slight chance of
showers and thuderstorms into Saturday night...with showers to
linger in the mountains on Sunday. The temperatures will remain
below normal into early next week then a high will arrive by
Monday with a warming trend into midweek.
Warm afternoon temperatures across much of the region today.
Slight cooling from the readings yesterday was expected but a
mostly absent marine incursion and weak offshore flow resulted in
higher minimum temperatures and that has been maintained through
the day. If not for a broad swath of high clouds across the region
the temperatures may have been even higher.
Other than adjusting temperatures upward a bit... most in Los
Angeles and Ventura County coastal plains and adjacent valleys...
little was changed in the general forecast package. Temperatures
tomorrow will be moderated by increasing amounts of cloud cover
and should be cooler. Weak offshore flow may continue for another
overnight though so the relative cooling may not be until later
in the day.
The primary weather of note is the incoming low pressure system
that will swing through beginning early Thursday. This system will
bring a shot at showers and thunderstorms to the region. The
best chance of either comes Thursday afternoon/evening and Friday
afternoon/evening in the Ventura and Los Angeles County mountains
and adjacent areas. The Ventura County mountains in particular
look to have good instability and strong positive buoyancy both
Thursday and Friday. However PWs are low on Thursday and marginal
on Friday. A pool of higher PW is expected to be to the south of
the region on Friday and if the low swings through farther north
than currently projected this may lead to a higher thunderstorm
probability. As it now stands... a chance to slight chance of
showers and thunderstorms appropriately represents the likelihood
A slight chance of showers continues across the region on
Saturday. The instability and CAPE both drop off notably on
Saturday so no thunderstorms are in the forecast but enough
moisture wraps around the low to keep showers lingering into the
mountains through early Sunday.
A moderate ridge begins to build over the region by late Sunday and
conditions return to warm and dry into the next work week.
At 2300Z, the marine inversion at KLAX was 700 feet. The top of the
inversion was 2000 feet with a temperature of 23 degrees Celsius.
Overall, low to moderate confidence in 00Z TAF package. High clouds
are obscuring the location of stratus this afternoon, making for a
low confidence forecast of where/when stratus may impact airfields.
Any stratus/fog that develops overnight will likely be IFR category
KLAX...low confidence in 00Z TAF. Moderate confidence in return of
stratus to airfield overnight, but low confidence in timing (+/- 3
hours of current 06Z arrival forecast). With strong onshore
gradients on Wednesday, stratus dissipation may be later than
KBUR...moderate confidence in 00Z TAF. There is a 50% chance of no
ceiling/vsby restriction overnight.
High confidence for coastal waters remaining below SCA levels
through Friday morning. There is a 40% chance for SCA level winds
from Friday afternoon to late Friday night across the very western
portion of zone PZZ670 from Point Piedras Blancas to Point Sal.