Scientific Forecaster Discussion
Area forecast discussion
National Weather Service San Diego California
900 PM PDT Thursday Jul 2 2015
Synopsis... drier and turning a little less humid Friday through
Sunday as the monsoon flow comes to an end. Southwest flow aloft
next week will bring seasonal weather and the marine layer will
slowly deepen through next Wednesday.
Discussion...for extreme southwestern California including Orange...
San Diego...western Riverside and southwestern San Bernardino
This monsoon episode is coming to a close. Precipitable water on the
00z nkx sounding this evening was 1... lower than
the 1.78" Wednesday evening. Dewpoints trended downward the past 24
hours with double-digit decreases in the San Diego County mountains.
Cumulus growth over the mountains this afternoon was limited by the lack
of available moisture and negative vorticity advection aloft.
The weather across Southern California will continue to transition
away from monsoonal flow and more toward a drier southwest flow.
Southerly flow between the large scale upper ridge over the Great
Basin and a quasi-stationary upper low over the Pacific will
continue through the weekend. Moisture advection into so-cal between
these two systems will be modest at best. Perhaps enough to support
afternoon cumulus...but thunderstorm chances are small.
Monday through Friday...the upper ridge will weaken and drift south
toward Sonora Mexico which will allow dry southwest flow to spread
across Southern California. Onshore flow will strengthen...the
marine layer will deepen...humidities will be much lower and
temperatures will trend closer to seasonal averages.
030300z...coast/valleys...stratus gradually developing along the
coast this evening and spreading 10-20 sm inland overnight...with
bases 700-1000 feet mean sea level...tops around 1500 feet mean sea level and areas of visible 3-5
sm. Visible below 3 sm is unlikely for the coast...however confidence is
higher for local visible at or below 1 sm for locations 5-20 miles
inland...particularly higher terrain. Confidence in stratus
occurrence is moderate to high...but low for ceilings making it into
kont. Clearing of stratus/fog during the 03/1600-1900 UTC time-
Mtns/deserts...few-sct clouds at or above 10000 feet mean sea level with unrestricted visible
prevailing through Friday.
800 PM...no hazardous weather is expected through Tuesday.
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.