Scientific Forecaster Discussion
Area forecast discussion
National Weather Service San Diego California
415 am PDT Tuesday Jul 29 2014
drying of the monsoonal moisture that brought thunderstorms the past
few days is underway...but the remaining moisture might be
sufficient for a few thunderstorms near the mountains this
afternoon. Drier weather will then prevail for much of the rest of
the week...but with some return of monsoonal moisture possible for
Friday into the weekend. Slow warming is expected into the weekend
followed by slow cooling into early next week. Weak onshore flow and
drying of middle and upper level moisture should allow for some return
of the marine layer for coastal areas over the next few days.
Discussion...for extreme southwestern California including Orange...
San Diego...western Riverside and southwestern San Bernardino
Short term (today through thursday)...
the drying that began yesterday afternoon has continued overnight.
Winds that were easterly in the middle and upper levels Sunday
afternoon and southeasterly early Monday morning had become
southwesterly Monday afternoon. Precipitable water values in the
lower deserts that were around 2 inches late Sunday and had fallen
to around 1.8 inches late Monday have fallen further overnight to
around 1.5 inches. There may still be enough residual moisture for a
few thunderstorms near the mountains this afternoon...mainly near
the ridge tops onto the desert slopes. Drier weather is then
expected to prevail for Wednesday and Thursday...but with some
afternoon clouds near the mountains possible. The models are in
better agreement with the moisture from weakening tropical cyclone
Hernan...generally taking it into the central California coast and
central California on Wednesday. There may be a few high clouds over
far southwestern California this morning from that moisture...but
otherwise not much impact is expected for far Southern California.
As the middle and high level moisture decreases...coastal stratus
should gradually return the next few nights. The workstation WRF
isn't overly aggressive with the return...mainly bringing it
northward from the northern Baja California coast along the coastal strip of
far Southern California the next few nights. Inland high
temperatures will slowly warm through Thursday.
Long term (friday through monday)...
some monsoonal moisture may return to the lower deserts for Friday
and Saturday with the GFS a day faster with drying after Saturday.
Afternoon clouds over the mountains should increase for Friday and
Saturday with a slight chance of thunderstorms added for the
mountains for Saturday afternoon. The current forecast leans toward
the faster drying of the GFS for Sunday/Monday. Patchy night and
morning low clouds and fog will continue for coastal areas. The
return of monsoonal moisture may bring minor cooling for
Friday/Saturday...followed by slow warming as the moisture
290945z...coasts/valleys...patchy stratus with bases 700-1000 feet mean sea level
and could reach ksan and kcrq for a time between 12-15z.
Otherwise...occasional scattered-broken clouds at/above 15000 feet mean sea level through
this afternoon. Stratus with bases 800-1200 feet mean sea level should be more
widespread tonight...reaching the coastal airports after 30/06z and
spreading 10-15 sm inland overnight.
Mountains/deserts...cu/tcu with bases 9000 feet mean sea level and a slight
chance of thunderstorms with tops to 35 kft over the mountains this
afternoon. Otherwise scattered-broken clouds at/above 15000 feet mean sea level and
unrestricted visible through this afternoon...becoming few-scattered tonight.
245 am PDT...no hazardous marine weather expected through Saturday.
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.