FXUS66 KSGX 150424
Area Forecast Discussion
National Weather Service San Diego CA
820 PM PST Thu Dec 14 2017
Santa Ana winds will continue at times through Sunday, with a quick
switch to onshore winds early Saturday. Friday will be another warm
day, then it will turn colder over the weekend as a trough moves
through. Colder next week as systems from the north bring
noticeably cooler weather to the region.
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
Winds are still gusting strongly in the mountains and foothills this
evening with gusts of 63 mph at Sill Hill, 45 mph at Boulder Creek,
and 43 mph at Descanso and Pleasants Peak. The winds will continue
overnight, then diminish Friday morning as the 1034 mb high over
southern Idaho this evening gives way to a 1016 mb surface low over
Nevada Friday afternoon.
Our long string of above average temperatures that began way back
during the week of Thanksgiving will finally come to end this
weekend. Friday will be the last day of unseasonable warmth, then a
deep, cold upper low will trek across Southern California Saturday
sending temperatures tumbling off a cliff. The trough will bring a
a brief period of onshore flow Friday night and Saturday when marine
layer clouds may appear in the coastal areas where they have been
conspicuously absent for a couple weeks. It'll turn windy in the
mountains and deserts with westerly wind gusts of 30-40 mph
Saturday. There is an outside chance for a brief shower over the
coastal waters Saturday, but the moisture and instability parameters
are marginal at best.
The winds switch back offshore behind the trough Saturday night
through Sunday morning for another round of offshore winds.with the
position of the surface high show the strongest winds in Orange/San
Bernardino/Riverside Counties with gusts of 40-60 mph in the
Next week the long range models show the high amplitude ridge
setting up a little farther west over the eastern Pacific. This
would allow cold northerly flow farther west into CA. Temperatures
in this pattern will be closer to average, especially the max
temperatures. Overnight lows with the dry cold airmass will result
in frost and possible freezing temperatures in the inland valleys
and parts of the lower deserts.
The nation's high today was right here in Southern California with
86 degrees at San Bernardino, Ojai, and Camarillo. At the opposite
end of the thermometer, the nations low was -15 at Silver Bay, MN,
Baldwin, MI, and Mount Washington, NH.
150400Z...A weakening trend in the offshore winds continue. However,
locally gusty NE winds with MOD-STG UDDFS/LLWS will continue over
and W of the mountains through 06-08Z Friday before winds weaken
further. Otherwise, P6SM vis and SKC-FEW250 will continue through
Friday night with VFR prevailing and winds less than 10 KT.
No hazardous marine weather is expected through Tuesday.
The Red Flag Warning currently in effect will continue through
Friday morning for inland areas with very low relative humidity
and gusty east to northeast winds. Winds will then weaken late
Friday and turn westerly early Saturday, then winds strengthen and
turn northeasterly late Saturday night through Sunday evening. A
Fire Weather Watch has been issued for the second Santa Ana event
expected on Sunday. Relative humidity will increase Saturday as an
upper-level trough moves across the region, then humidity drops
again Sunday with the offshore flow. Conditions will improve
Sunday night into early next week.
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
CA...Red Flag Warning until 10 AM PST Friday for Orange County Inland
Areas-Riverside County Mountains-Including The San Jacinto
Ranger District Of The San Bernardino National Forest-San
Bernardino County Mountains-Including The Mountain Top And
Front Country Ranger Districts Of The San Bernardino
National Forest-San Bernardino and Riverside County Valleys
-The Inland Empire-San Diego County Inland Valleys-San
Diego County Mountains-Including The Palomar And Descanso
Ranger Districts of the Cleveland National Forest-San
Gorgonio Pass Near Banning-Santa Ana Mountains-Including
The Trabuco Ranger District of the Cleveland National
Fire Weather Watch from late Saturday night through Sunday
evening for Orange County Inland Areas-Riverside County
Mountains-Including The San Jacinto Ranger District Of The
San Bernardino National Forest-San Bernardino County
Mountains-Including The Mountain Top And Front Country
Ranger Districts Of The San Bernardino National Forest-San
Bernardino and Riverside County Valleys -The Inland Empire-
San Diego County Inland Valleys-San Diego County Mountains-
Including The Palomar And Descanso Ranger Districts of the
Cleveland National Forest-San Gorgonio Pass Near Banning-
Santa Ana Mountains-Including The Trabuco Ranger District
of the Cleveland National Forest.