Scientific Forecaster Discussion
Area forecast discussion
National Weather Service San Diego California
945 PM PDT Tuesday Mar 11 2014
patchy low clouds and fog are returning to the coast this evening.
However...moderate to locally strong and gusty north to northeast
winds will develop across the northern areas later tonight and for
Wednesday...quickly pushing the low clouds out over the waters by
Wednesday morning. Very dry conditions will also develop...with
temperatures similar to or slightly cooler through Friday. Hot and
dry conditions will then develop for the weekend and early next
week...as a very strong ridge of high pressure builds over the west.
Discussion...for extreme southwestern California including Orange...
San Diego...western Riverside and southwestern San Bernardino
Water vapor imagery shows a trough of low pressure retrograding and
digging over Nevada this evening....with a rather impressive dry
slot and upper level jet over northern California. Water vapor
imagery also shows high pressure nosing into the Pacific northwest
this evening...with a couple of weak upper level disturbance south
of this high that are west of 130 and moving in opposite
directions. The low along 30 north...which is drifting towards
Southern California...will be absorbed into the flow over the next
36 to 48 hours...so expect periods of high clouds to continue.
Otherwise...just watching the marine layer return to the coastal
areas and the offshore pressure gradients to the north increase at
The current San Diego to Tonopah gradient is up to -9.3 mbs...and is
forecast to peak Wednesday morning between 14 and 15 mbs.
Meanwhile...the San Diego to Daggett gradient is fluctuating a bit
around -2.4 mbs...but will likely increase to around 8 or 9 mbs
Wednesday morning. The 00z NAM and the WRF have backed off the
super strong winds of the past few days...in part due to the
placement of the upper level low. At this time...they are only
showing 850 mb winds of 40 kts...with 925 mb and 30 above ground level winds at 45
kts. Therefore...still be the favored windy spots through and below
the canyons and passes as well as along the coastal foothills will
likely see gusts up to 65 miles per hour...but most other areas will just be
gusty. For this reason...the current winds products look on track.
These moderate to locally strong and gusty winds will also quickly
push the marine layer out over the coast waters by morning.
These winds will gradually weak late Wednesday and Thursday...as
this upper level low digs over Southern California. Therefore...not
expecting much change in temperatures for Thursday...with the very
dry conditions prevailing. As this upper level low shift east on
Thursday night and Friday...high pressure will then start to build
back over the region. In fact...this ridge of high pressure will be
very strong by the weekend...and centered over California through
early next week. As a result...unseasonably hot conditions will
develop...as 850 mb temperatures peak over Southern California
between 19 and 21 degrees. In fact...some of the inland valleys may
be flirting with the 90s for Sunday and Monday...and cannot rule out
that some records may fall. This means that the very dry conditions
will also continue....with weak offshore flow continuing.
120415z...coast...areas of stratus will affect locations within 5-10
miles of the coast through about 11z...then mostly retreat to the
ocean. Bases will be 800-1200 feet mean sea level with tops to 1500 feet mean sea level. Most
visible will remain 5+ miles. For coastal airports...such as ksan and
kcrq...the ceilings will most likely be tempo versus prevailing.
Areas of northeast winds will develop late tonight in Orange County
and Thursday in San Diego County coastal areas. Surface gusts could
exceed 30 knots near coastal canyons of southern Orange County. Low level wind shear
will occur at times from ksna to kokb and kcrq. Winds will weaken
after 20z Wednesday.
Valleys/mtns/deserts...northeasterly winds will increase
tonight...with surface gusts to 55 knots possible through passes and along
the coastal mountain slopes. Rotors and low level wind shear will occur near coastal
foothills and valleys...including kont where low level wind shear will be quite
strong. Winds will weaken after 22z Wednesday. Otherwise...no ceilings or visible
restrictions through Wednesday evening.
elevated surf...with isolated sets 5 to 6 feet...will continue this
week along westerly facing beaches as moderate northwest swells arrive.
Strong and dangerous rip currents will occur at times the rest of
Local NE gusts to 25 knots will be possible over the nearshore
waters Wednesday morning...mainly north of Oceanside.
a red flag warning for strong northeast winds and low humidity
remains in effect for Wednesday. In addition...reports indicate
that in many areas fuels have not sufficiently responded to the
recent rains to reduce the wildfire threat.
The winds will increase later tonight...but humidity will not fall
below the 15 percent threshold until late Wednesday morning. The
winds will peak Wednesday morning through midday...then gradually
decrease during the afternoon. Strongest wind gusts exceeding 50
miles per hour will occur through and below passes and canyons of the San
Bernardino and Santa Ana Mountains. Continued dry and breezy on
Thursday...but conditions are not expected to be critical due to
lighter winds and some humidity recovery. Very warm and dry...with
weak offshore flow for the weekend.
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
California...red flag warning from 6 am to 6 PM PDT Wednesday for the
Coachella Valley-including the Palm Springs South Coast
desert district...Orange County coastal areas...Riverside
County mountains-including the San Jacinto Ranger district
of the San Bernardino National Forest...San Bernardino and
Riverside County valleys-the inland Empire...San Bernardino
County mountains-including the mountain top and front
country Ranger districts of the San Bernardino National
Forest...Santa Ana Mountains-including the Trabuco Ranger
district of the Cleveland National Forest.
Wind Advisory until 6 PM PDT Wednesday for the Coachella
Valley...Orange County coastal areas...Riverside County
mountains...San Bernardino County mountains...San
Bernardino and Riverside County valleys-the inland Empire...
Santa Ana Mountains and foothills.