Scientific Forecaster Discussion
fxus66 ksgx 250403
Area forecast discussion
National Weather Service San Diego California
803 PM PST Fri Nov 24 2017
cooler weather will gradually build from the coast to inland areas
through the weekend. A fast moving low pressure trough will bring
much cooler but nearly seasonable temperatures on Monday with a
chance of light rain showers for all areas except the deserts. As
marine influenced air returns, areas of dense fog could return to
coastal areas this weekend. Gusty westerly winds will develop
over the mountains and deserts Sunday night through Monday night,
turning offshore again by Tuesday morning as the trough passes to
the east. A stronger Santa Ana weather pattern with strong winds
and low relative humidity could develop around Wednesday and
persist through Friday next week.
Discussion...for extreme southwestern California including Orange...
San Diego...western Riverside and southwestern San Bernardino
Tranquil conditions continue across Southern California this
evening after another very warm day. More records were broken yet
..highest maximum temperature records broken or tied on Nov 24 2017 ...
Location new record old record period of record
Vista 89 tied 89 in 1975 1957
alpine 86 tied 86 in 1959 1951
El Cajon 92 89 in 1995 1979
big bear 70 68 in 1970 1960
Campo 88 85 in 1970 1948
Borrego 90 87 in 2012 1942
Satellite imagery shows a mainly clear sky with just a few high
cirrus clouds moving in from the west. Some low clouds have
developed off northern baja and even just off the southern San
Diego County coast. Hrrr shows most of this remaining offshore or
just along the beaches as a weak eddy develops with S-southeast winds
keeping most of the low clouds and/or patchy fog just off the
coast overnight, but then moving a bit inland Sat morning. So
some low clouds forecast especially near the San Diego County
coast by Sat morning. No significant changes were made to the
forecast this evening. See previous discussion below for further
..previous discussion (issued at 318 PM PST Fri Nov 24 2017)...
Thin high clouds streaming across central and Southern California
this afternoon from the subtropics with some wave clouds noted on
the hi-res satellite loops over the Tehachapi Mountains. Far
Southern California remains mainly sunny however.
Temperatures have been trending a few degrees cooler today
although inland and Mesa areas remain significantly warmer than
normal for late November with Miramar one of the warmest locations
recently hitting 94 degrees.
The high pressure ridge predominantly responsible for the recent
heat wave will gradually shift southeast and replaced with a troughy
pattern through early next week. Gradually cooler conditions will
develop over the weekend with the coolest day likely to be Monday
when a vigorous upper level trough originating from the Gulf of
Alaska passes through central California into the Great Basin
through Tuesday. This system could bring some light rain showers
to all areas from Monday morning in Orange County through Monday
afternoon, with chances for rain added to all areas except the
Brief offshore flow still looks to occur Tuesday morning in the
wake of the upper trough with gusts in favorable offshore canyons
and coastal slopes of 30 to 40 mph possible. At this time the
magnitude of this event looks to be moderate at best and only last
for about 12 hours.
Medium range forecaster confidence becomes quite poor Wednesday
and beyond with the ec indicating the potential for another Santa
Ana event but the strongest gradients well to the NE for Thursday
and Friday. A cutoff low may develop off the socal coast and
persist through the end of the work week which makes the forecast
of Santa Ana related weather conditions highly difficult this far
out. However without an upper level ridge temperatures will warm a
bit above normal but not likely to be significantly above normal.
250400z...coast...low stratus and dense fog will likely develop near
the beaches late tonight and early Saturday morning with possible
cigs below 400 feet mean sea level and vis below 1 mile. The chance is low for
a cig at ksan, kcrq or ksna through at least 12z Sat, though the
risk increases some between 12z and 16z Sat for ksan/kcrq. Low
stratus/fog could linger along the beaches Sat afternoon and then
spread a few miles inland Sat night. Ksan, kcrq and ksna could have
vlifr or LIFR conditions Sat night.
Valleys, mountains and deserts...mostly sct clouds above 20000 feet
mean sea level will prevail with unrestricted vis through Sat night.
areas of dense fog may develop over the coastal waters late tonight
and Saturday morning with a greater chance Saturday night.
Visibility may be reduced to 1 nm or less at times.
A trough of low pressure moving through on Monday will bring
northwest winds gusting 20 to 25 kt over the outer waters.
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.