Weather Service Report

FXUS66 KLOX 061156

456 AM PDT FRI MAY 6 2016


A slow-moving low pressure system will bring a chance of showers
and a slight chance of thunderstorms to the region through the
weekend. High pressure will rebuild next week bringing mostly
clear skies with a warming trend to the area Monday through the
middle of next week. Night through morning low clouds and patchy
fog are likely for some coastal areas and coastal valley
locations through much of next week.



An unseasonably cold upper low was centered just west of Point
Conception this morning. This upper low is expected to move
slightly to the southeast and remain over Southern California
through Saturday before moving east. There will continue be some
upper level disturbances rotating around and within the upper low
over the forecast area today. 500 mb Temps will be quite cold for
this time of year at around -22 degrees C. This will be the main
factor to cause the atmosphere to become quite unstable with high
lapse rates...especially over the mountains this afternoon and
evening. Confidence is high that there will be scattered
thunderstorms developing over the mountains this afternoon and
evening. Latest model soundings near Lockwood Valley in the
Ventura Mtns indicated high CAPE values over 1,100 j/kg, Lifted
Index around -6 and plenty of low- mid level moisture to work
with. Unlike yesterday, the upper flow will be much weaker due to
the proximity of the upper low. Therefore a FLASH FLOOD WATCH has
been issued for the Los Angeles, Ventura, Santa Barbara County
Mountains, as well as the Antelope Valley and Cuyama Valley valid
from noon today through 8 pm this evening. The Precipitable Waters
are around .85 inches which is also high for this time of year.
People in the flash flood watch areas should keep an eye on the
weather today.

Once again, it will be difficult to pin-point when and where coast
and valley showers will occur today. There will be a slight chance
for thunderstorms across the SBA,VTU,LA Valleys and coastal areas
as thunderstorms will likely drift to the SE off the mountains. 
There will be enough instability continuing into this evening to
continue the slight chance of thunderstorms. The upper low will
continue to swing some moisture over the forecast through
Saturday. Showers will be less widespread and not as
convective...however there will continue to be slight instability
over the mountains on Saturday so a few isolated thunderstorms
can't be ruled out. Winds will remain fairly week out of the
north, so there could be a few late afternoon showers drifting
into the valleys and coastal areas of LA,VTA and SBA counties. 

By Sunday...the upper low will be well into the Central Plains,
but there will continue to be some lingering moisture across the
region, so expect at the least partly cloudy skies. Went ahead and
pulled out POPS for Sunday as latest models showed no rain and a
much more stable atmosphere. There will likely be a flat cumulus
clouds across the mountains and foothills...but cloud cover should
not be as widespread across coast and valleys. 

As far as high temps go...due to the clouds and unsettled weather
conditions, temps will be much cooler than normal across the area
today thru Sun, with highs ranging from 7 to 16 deg below normal
today. High temps will continue to be below normal for this time
of year, but trend towards normal by next Tuesday. Hi temps for
the cst and vlys will be generally in the 60s today, then warm
slightly into the mid 60s to low 70s for Sat, and upper 60s to
lower 70s for Sun.


EC/GFS continue to be in good agreement Mon thru Thu. 
Upper level ridging will build off the California coast Monday
and become amplified by Tue. This ridge will then shift over
California Wednesday and Thursday. Expect dry and warmer
conditions through the extended period. Some night and morning
marine layer low clouds and fog should affect some coastal and
coastal valley areas at times, otherwise clear to partly cloudy
skies can be expected across the region for Mon thru Thu. High
temps will be around normal by next Tue and Wed, and then warmer
than normal for many areas by Thursday, with the warmest vlys
reaching the mid 80s.



At 12Z...There was no marine inversion at KLAX.

Low to moderate confidence in the current forecast. Ceilings at
or below 5000 feet will be prevalent across the region. Periods of
MVFR conditions are possible in rain/showers. There is a chance of
IFR conditions in heavier rain/showers. There is a slight chance
of thunderstorms east of KNSI-KSBA-KPRB line.

KLAX and KBUR...Low to moderate confidence in the current
forecast. Ceilings at or below 5000 feet will be prevalent.
Period of MVFR conditions are possible in rain/showers, mainly
between 16Z and 22Z. There is a 20 percent chance of
thunderstorms and a 30 percent chance of IFR conditions during
this time.


.MARINE...06/300 AM.

There is a chance of showers across the coastal waters through
Saturday night and a slight chance of thunderstorms today, mainly
south and east of the Channel Islands. Any storms that develop
will be capable of brief heavy downpours, gusty winds, small hail,
and dangerous cloud to ground lightning. Winds and seas should
remain below advisory criteria through Sunday, except in the
vicinity of any thunderstorms that develop.

The storm system moves out the of region by late Sunday and no
significant wind or sea conditions are expected through the early
half of next week.


CA...Flash Flood Watch in effect from noon PDT today through this
      evening For zones 38-52>54-59. (See LAXFFALOX).




Return to Home page

Western Regional Climate Center,