Area forecast discussion
National Weather Service San Diego California
145 PM PDT Monday may 20 2013
Synopsis...
high pressure will give way to a digging trough of low pressure over
the next 24 to 36 hours...with this trough dominating the weather
along the West Coast through early next week. Therefore...expect a
gradual cooling trend to start on Tuesday...with much cooler
conditions developing Wednesday and Thursday. Temperatures will
remain below normal through Monday...with only minor day to day
fluctuations possible. The marine layer will deepen as well this
week...with more extensive low clouds each night and some drizzle
possible by Thursday morning. Gusty west winds will also develop
each afternoon and evening in the mountains and deserts.
&&
Discussion...for extreme southwestern California including Orange...
San Diego...western Riverside and southwestern San Bernardino
counties...
Water vapor imagery continues to show northwesterly flow aloft over
California this afternoon...with high pressure still along the West
Coast. However...a vigorous and unseasonably cold trough of low
pressure is digging inside of 140 west between 40 and 50
north...which will become the dominate weather feature along the
West Coast this week. In the meantime though...sunny and warm
conditions are prevailing across the Southland this afternoon.
Temperatures are running up to 13 degrees warmer than this time
yesterday...with the greatest warming occurring across the inland
valleys. This will make for a very pleasant evening across the
region. An eddy will reform though tonight over the bight...helping
the marine layer to redevelop and push back into the coastal areas
and western valleys.
As this aforementioned trough slowly digs along the West Coast over
the next 24 to 48 hours...a gradual cooling trend will begin. At
this time...conditions on Tuesday will still be relatively warm
across the Southland...especially across the inland areas...with
temperatures remaining above normal. A more noticeable and
significant cooling trend will start on Wednesday though...as
temperatures fall near to below normal. This trough trough will
remain over the West Coast this week...sending a series of
disturbances across the Pacific northwest and northern California
through early next week. Therefore...only expect minor day to day
fluctuations possible in the temperatures through Monday. At this
point in time though...Friday looks like it may be the warmest day
of the week after today...but even then...temperatures will still
likely range between 5 and 15 degrees below normal. The marine
layer will also deepen a bit each day...with the potential for some
drizzle possible by Thursday morning. Therefore..expect a more
extensive marine stratus deck to develop and push inland each
night...with minor fluctuations in its height as well. This trough
will also bring stronger onshore flow to the Southland...with
locally gusty west winds developing each afternoon and evening
across the mountains and deserts.
&&
Aviation...
201939z...coast/valleys...through 21/0400 UTC...unrestricted visible and
sky clear. 21/0400-0900 UTC...stratus moving 10-15 sm inland...with bases
900-1300 feet mean sea level and tops around 1600-1800 feet mean sea level. These conditions
will continue through 21/1500 UTC. 21/1500-1800 UTC...stratus
clearing to the coastal waters.
Mtns/deserts...unrestricted visible through Tuesday morning...with
scattered-few clouds at or above 20000 feet mean sea level after 21/1200 UTC.
&&
Marine...
a 3 foot/16-17 second period southwest swell will continue through
midweek...generating elevated surf and strong rip currents along
south and southwest facing beaches. Highest surf of around 4 to 6
feet with local sets to around 7 feet are possible on exposed
southwest facing beaches.
A 6 to 8 foot short-period northwest swell will move into the outer
coastal waters Wednesday and Thursday...creating choppy seas in
areas south and west of San Clemente Island. The swell will
also bring elevated surf to exposed west facing shores.
&&
Sgx watches/warnings/advisories...none.
&&
$$
Public...Palmer
aviation/marine...Harrison
