Area Forecast Discussion


080 
FXUS66 KSGX 150424
AFDSGX
Area Forecast Discussion
National Weather Service San Diego CA
820 PM PST Thu Dec 14 2017
.SYNOPSIS...
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
COUNTIES...
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 
windiest locations. 
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. 
&&
.AVIATION... 
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.
&&
.MARINE...
No hazardous marine weather is expected through Tuesday.
&&
.FIRE WEATHER...
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... 
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
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 
     Forest.
     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.
PZ...NONE.
&&
$$
PUBLIC/FIRE WEATHER...Moede
AVIATION/MARINE...Gregoria