Area Forecast Discussion
Issued by NWS San Diego, CA
FXUS66 KSGX 271543
AREA FORECAST DISCUSSION
National Weather Service San Diego CA
842 AM PDT SAT AUG 27 2016
High pressure to the southwest will bring a warming trend into early
next week. As the marine layer thins, low clouds and fog will pull
back toward the coast through Tuesday. For the middle and latter
part of next week...a trough of low pressure will redevelop along
the West Coast, bringing a cooling trend and slow deepening of the
marine layer. Even cooler weather is likely for the Labor Day
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
Low clouds were extensive this morning for hundreds of miles
offshore of the CA coast, and covered most of the coastal basin to
the mtn foothills. the 12Z Miramar sounding had an 8.5 degree C
inversion based near 3500 FT. There was a 900 FT saturated layer,
suggesting a fairly thick cloud layer and slow clearing this
morning. At 8 AM PDT, Surface pressure gradients were a bit weaker
onshore than yesterday morning, with light winds reported across the
Looks like a great day shaping up as the marine clouds clear,
leaving afternoon temperatures well below late August averages.
Skies will be sunny by afternoon most areas, with a few cumulus
possible over the mountains.
The weak upper-level trough over the region this morning will slide
east through Monday as high pressure off the coast builds NE across
SoCal. This will result in a dramatic drop in the marine layer depth
Sun into Tue. It will also drive max temps back to average far
inland on Sun, then above average Mon/Tue most areas.
The warm weather will be short-lived as another long wave trough
develops along the West Coast by the middle of next week. This will
keep our late summer temperatures below average, with the model
trends indicating a cool Labor Day weekend shaping up as the marine
layer and the upper-level trough deepen. The chance for any
monsoonal moisture reaching SW CA looks very small during the next
week, but may have a short window open near the middle of next week.
271530Z...Coast/Valleys...Stratus will clear slowly today, 16Z-18Z
in the valleys and 18Z-20Z near the coast. Cloud bases will be 2000-
2500 ft MSL with tops to 3000-3500 ft MSL with higher terrain
obscured. Local vis will be 3-5 mi in the valleys through 18Z.
Mostly clear skies will prevail this afternoon, with stratus
spreading through coastal areas 02Z-06Z and up to 30 miles inland by
12Z Sun. Bases will be lower, mostly 1400-1800 ft MSL with tops to
2200 ft MSL. Areas of vis 2-4 mi will occur in the valleys 09Z-16Z
Sun. Most areas will clear 15Z-17Z Sun.
Mountains/Deserts...Sct cumulus will occur over the deserts of San
Bernardino County and most mountain areas through 02Z this evening,
with bases mostly at/above 9000 ft MSL. Isolated cumulus will be
possible Sunday afternoon. Otherwise, mostly clear skies with
unrestricted vis will prevail through Sunday.
No hazardous marine weather is expected through Thursday.
Skywarn activation will not be needed today.