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Area forecast discussion
National Weather Service San Diego California
935 am PST Tue Nov 21 2017

Synopsis...
high pressure aloft will bring hot, dry weather this week with
record highs likely. A slow cooling trend will begin Friday, but
above average temperatures will continue into early next week. The
ridge breaks down next week, but the storm track remains too far
north for significant chances of rain through the end of the month.

&&

Discussion...for extreme southwestern California including Orange...
San Diego...western Riverside and southwestern San Bernardino
counties...

Temperatures rose quickly with the Rising Sun and 9 am temperatures
already 5 to 15 degrees higher than 24 hours ago. Myf and nkx were
already 80 degrees. Campo was 78 with a northeast winds at 20 mph.
Record highs are possible this afternoon at Ramona (87), Palomar
Mountain (72) and Campo (83).

Pressure gradients were more strongly offshore this morning compared
to yesterday with san-tph (-9.7 vs -3.7), strong enough to support
easterly wind gusts of 25 to 40 mph in and below the favored
mountain passes. A 1030 mb surface high over western Colorado will
remain in place through Thursday morning so these local offshore
winds will continue until then.

The strong upper level ridge will be the dominate feature over the
southwest this week. 500 mb peak at 594 dm on Wednesday, then trend ever
so slowly downward to 588 dm Sunday. Record highs are likely just
about anywhere from the coast to the deserts on Wednesday and
Thursday. Weak offshore flow and the associated downslope warming
will send valley temperatures soaring into the mid 90s. It's quite
likely that temperatures here in Southern California will be the
highest in the land.

The ridge weakens this weekend and it won't be quite as hot, but
temperatures will still be 5-15 degrees above average Saturday and
Sunday. We will see greater cooler early next week when a weak
trough passes by to our north. The feature will be too far north for
rain down here, and dry weather is looking likely through the end of
the month. The last time San Diego failed to record measurable rain
in November was 1980.

&&

Aviation...
211604z...sct-bkn clouds at or above 20000 ft msl becoming few after 22/0300
UTC. P6sm vis will continue through Wednesday morning. After 22/1200
UTC, NE to east winds increasing to 15-25 kt with gusts 30-35 kt
resulting in moderate-strong uddfs/llws over and west or SW of the
mountains.

&&

Marine...
no hazardous marine weather is expected through Saturday.

&&

Fire weather...
a Santa Ana weather pattern will be in place through Thursday with
warm, dry weather and locally gusty winds of 25-40 mph in and below
the mountain passes and canyons. The strongest gusts this morning
were 40 mph at Pleasants Peak in Orange County, and Sill Hill in San
Diego County. Below the Cajon Pass, winds gusted to 35 mph at
DeVore. These localized winds will continue through Thursday,
strongest each morning. Afternoon humidities will fall into the
teens the next few days. Although red flag conditions are not
expected, fire weather conditions will be elevated and any fires
that start may spread quickly. Areas of greatest concern include
locations below the Cajon and Banning passes, and the passes and
canyons of the Santa Ana and San Diego County mountains.

&&

Skywarn...
Skywarn activation will not be needed this week.

&&

Sgx watches/warnings/advisories...
California...none.
Pz...none.
&&

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