Weather Service Report


101 
FXUS66 KSGX 282049
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
149 PM PDT Wed Jun 28 2017

.SYNOPSIS...
Near average temperatures, night and morning coastal low clouds 
and mostly sunny skies inland will prevail through the 4th of 
July. Brief periods of elevated fire weather conditions are 
anticipated over and east of the mountains ridges each afternoon 
and evening. Otherwise no potentially hazardous conditions are 
expected.

&&


.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...

At 130 PM, Low amplitude ridging remained in place over the 
Southwest US. Skies were mostly clear, with low clouds limited to
the coastal waters. Winds remained breezy through the passes with
local gusts of 30-45 mph. As expected temperatures are noticeable
cooler than this time yesterday, with some locations over the 
valleys running 10-15 degrees F cooler than this time yesterday.

The low stratus currently hovering off the coast should make a
push inland after sunset, bringing increasing low cloud cover to 
the coast and western valleys through early Thursday morning. 
Patchy dense fog is possible over the higher valley terrain.
Cooling will continue Tuesday, with 3-5 degrees F of cooling in 
the 950-850 mb layer leading to an additional 3-6 degree F drop in
afternoon highs over the valleys.

Friday through the middle of next week, the forecast can be 
described by one word "seasonal". Upper level ridging will 
generally remain in place over or just off the West Coast, as a 
few weak troughs ride over the ridge. This will result in minor 
day to day temperatures fluctuations, standard afternoon sea 
breezes, and night and morning low clouds over the coast and 
western valleys.

Toward the second half of next week, both the ECMWF and GFS
suggest a shift in the position of the upper level ridge axis 
toward the Four Corners or western Plains. Along with the 
potential development of a weak mid level (850-500 mb) trough off 
the West Coast, this may allow for a push of monsoonal moisture 
into the AZ/CA/NV region. Though uncertainty on the specifics of 
the forecast remain high, moderate run-to-run consistency in the 
global models lends itself to modest forecaster confidence in the 
general synoptic pattern for this period.

&&


.AVIATION... 
281900Z...Coast/Valleys...Clear this afternoon except for a few low 
clouds at the beach near the border. Extensive areas of low clouds 
remain about 20 miles offshore. The low clouds will likely return to 
the coastal TAF sites after 00Z Thu with bases 1000-1500 ft MSL and 
tops near 2000 ft MSL. Expect the clouds to spread into the western 
valleys overnight, with vis 1-3SM where clouds and terrain 
intersect. Confidence is moderate that KONT will be impacted.

Mountains/Deserts...Clear skies with unrestricted vis will prevail 
through Thursday. West winds locally gusting 20-25 kt will produce 
LLWS and weak-mdt up/downdrafts over and east of the mountains 
through this afternoon. Winds will weaken by late evening.

&&


.MARINE...
No hazardous marine weather is expected through Sunday.

&&


.FIRE WEATHER...
Breezy winds will continue this afternoon and evening over and 
east of the mountain ridges, especially in Riverside and San Diego
Counties, where westerly wind gusts of 25-45 mph are expected. 
Relative humidity values will remain in the low teens and single 
digits through this evening. As such, the fire risk remains 
elevated. West of the mountain ridges, significant relative 
humidity recovery will limit the fire risk. Minimum relative 
humidity values in the single digits and teens and west winds in 
the afternoons will keep the fire risk elevated over and east of 
the mountain ridges through the 4th of July Holiday.

&&

.SKYWARN... 
Skywarn activation will not be through the middle of next week.


&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...NONE.
&&

$$

PUBLIC/FIRE WEATHER...Albright
AVIATION/MARINE...PG

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Western Regional Climate Center, wrcc@dri.edu