Scientific Forecaster Discussion
Area forecast discussion
National Weather Service San Diego California
845 PM PDT Monday Sep 29 2014
dry northwest flow aloft and onshore flow will keep the weather fair
and seasonal through Wednesday. For Thursday into Sunday...high
pressure building aloft and weak to locally moderate offshore flow
will bring increasingly hotter and drier days. Daytime temperatures
could be around fifteen degrees or more above average by Friday west
of the mountains. Cooler Sunday into next week as the high weakens
Discussion...for extreme southwestern California including Orange...
San Diego...western Riverside and southwestern San Bernardino
Afternoon temperatures were between 5...to as much as 10 degrees f
higher than yesterday. Warming was also observed on the 00z Miramar
sounding...which had increases of 3-5 degrees c between 950 and 400
mb. Slight warming is likely Tuesday/Wednesday but overall...no major changes
are expected with temperatures about average for this time of year.
Surface pressure gradients have become quite weak along with the
No changes to the forecast this evening as model consensus supports
building high pressure over the West Coast this week and weak to
moderate offshore flow by Thursday...continuing through Sunday.
Before the offshore flow begins...onshore flow will increase
again...and a coastal eddy is likely to develop Tuesday night with areas
of low clouds possible along the coast and pleasant temperatures and
humidity through Wednesday. By Thursday...the marine air will be pushed
back offshore and much drier air with bigger diurnal temperature
swings will rule west of the mountains through sun.
A heat advisory may Abe needed this weekend...particularly in the
valleys where daytime highs are likely to spike past the century
mark for several hours.
The ridge of high pressure aloft is forecast to gradually weaken sun
through Wednesday of next week. This will allow weak onshore flow to
gradually increase...spreading cooler marine air inland...along with
increasing moisture from the south. Temperatures should be closer to
average inland by the middle of next week if the models verify. Near
the coast...average high temperatures should return sooner in the
300330z...coasts/valleys...patchy stratus with bases 1000-1500
developing along the coast and up to 10 Michigan inland late tonight or
early Tuesday morning. Confidence in timing and occurrence of ceilings at
the coastal airports is low...though best chances appear to be
between 10-16z. Mostly clear after 16z. Stratus with bases 800-1200
feet mean sea level should form over the coastal waters Tuesday afternoon...moving
into the coastal areas Tuesday evening.
Mountains/deserts...clear with unrestricted visible through Tuesday evening.
900 PM...no hazardous marine weather is expected through Friday.
hot and dry conditions will develop Thursday and persist through the
weekend as a ridge of high pressure aloft builds over the area...and
weak to locally moderate offshore winds develop at the surface. The
strongest winds are expected late Wednesday night/early Thursday morning...
with local wind gusts 30-40 miles per hour possible along favored ridges...
coastal slopes/foothills and through mountain passes/canyons. Winds
are expected to gradually weaken late Thursday through early Sat.
Just inland...afternoon relative humidity will fall to 5 to 15 percent...with poor
overnight recovery. The hot...dry and locally gusty conditions will
elevate the threat of wildfires. Since the stronger wind gusts are
not expected to be long-lived and will likely be localized...no fire
weather hazard products are planned at this time.
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.