Area Forecast Discussion
Issued by NWS San Diego, CA
FXUS66 KSGX 240403
AREA FORECAST DISCUSSION
National Weather Service San Diego CA
903 PM PDT SAT JUL 23 2016
The cooling trend continues on Sunday, with daytime temperatures a
few degrees lower than today. Cooling is likely to be more
noticeable in the coastal areas and the San Diego county valleys,
accompanied by an increase in night-and-morning Marine Layer low
clouds and fog. Next week, Temperatures will be near to slightly
above seasonal averages under easterly flow aloft with periods of
higher clouds, and a shallow marine layer along the coast. Toward
the end of the week, scattered shower and thunderstorm activity
may develop over the mountains and deserts.
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
Mostly clear this evening, except for a few low clouds off the
immediate coast and some high clouds over northern Baja.
The coastal eddy that developed this morning is expected to
persist through Sunday, even as the upper level high pressure
weakens. This will continue the general cooling trend, with temps
decreasing by a few degrees F over most of the region. In
addition, sfc pressure gradients are trending more onshore. This
combination of factors will likely bring a somewhat deeper marine
layer tonight into Sun morning, with low clouds and fog extending
farther inland. Expect the cooling to be more noticeable in the
coastal areas and the San Diego County valleys.
The numerical models indicate a fairly stable low-amplitude pattern
for next week, with an east-west oriented sub-tropical ridge of
high pressure dominating over the eastern pacific and southwestern
U.S. For most of next week, the ridge axis will remain just far
enough to the north for easterly flow aloft over SOCAL but not
enough to allow for sufficient moisture to support deep
convection. It will keep temperatures near or somewhat above
seasonal averages, with a shallow marine layer for coastal low
clouds and fog during the nights and mornings. Minor day-to-day
variations in the temps and the marine layer should be expected.
A shift in the position of the upper ridge could allow for an
increase in monsoonal moisture, improving the chances for the
development of afternoon showers/tstms toward the end of next
240400Z...Coast...Areas of stratus will likely redevelop within 15
miles of the coast overnight, though timing of arrival at coastal
airports, including KSAN, is low confidence, with best chances of
arrival between 06Z and 10Z. Bases will be 600-900 ft MSL with tops
to 1300 ft MSL. There is a chance of vis below 3 miles, possibly 1
mile, over higher coastal terrain, possibly including the San Diego
County mesas, VCNTY KCRQ, KMYF and KSDM. Most areas will clear 16Z-
18Z Sunday with local BKN conditions possibly continuing near the
beaches Sunday afternoon.
Valleys/Mountains/Deserts...Some smoke will occur in San Bernardino
County from the Sand Fire of LA County, but most vis will remain
above 5 miles. Otherwise, increasing clouds above 15000 ft MSL with
unrestricted vis will occur through Sunday.
No hazardous marine weather is expected through Thursday.
Skywarn activation will not be needed on Sunday.
CA...Heat Advisory until 8 PM PDT Sunday for Apple and Lucerne
Valleys-Coachella Valley-Riverside County Mountains-San
Bernardino County Mountains-San Bernardino and Riverside
County Valleys-The Inland Empire-San Diego County Deserts-
San Diego County Mountains-San Diego County Valleys-San
Gorgonio Pass Near Banning.
Heat Advisory until 8 PM PDT this evening for Orange County
Inland Areas-Santa Ana Mountains and Foothills.