Scientific Forecaster Discussion
fxus66 ksgx 160425
Area forecast discussion
National Weather Service San Diego California
930 PM PDT Sat Jun 15 2019
weak low pressure aloft will maintain typical June weather with
near to slightly below normal daytime temperatures and marine
clouds and fog spreading well inland each night. Midday clearing
back to coastal areas is expected, but clearing may be delayed or
limited some days due to fluctuations in the marine layer and cloud
depth. The deserts will be seasonably hot under fair skies. Slight
warming is possible mid next week as a ridge attempts to build
aloft, but a return to cooler weather is likely before the
Discussion...for extreme southwestern California including Orange...
San Diego...western Riverside and southwestern San Bernardino
Stratus was again spreading inland this evening, with total coverage
over Orange County and within 20 miles of the San Diego County
coast. With marine inversion bases around 1500 feet and an mslp
gradient of 9.0 mb onshore from san to ipl, there should be no
problem with stratus covering nearly all valleys overnight and early
Sunday. Guidance suggests similar clearing Sunday with some
lingering clouds during the afternoon near the coast. Slight cooling
aloft should lower the inland temperatures a couple degrees, but
otherwise little change is expected. With the thermal gradient
continuing between the valleys and the hotter deserts, there should
be moderate winds in the mountains and deserts again Sunday
afternoon/evening with local gusts over 40 miles per hour.
From previous discussion...
A series of weak troughs will maintain low pressure aloft over socal
through early next week, supporting the marine layer and holding
daytime temperatures a bit below average. Marine stratus will
continue to surge well inland each night, but should clear back to
coastal areas each day. No guarantee on any given day or time for
sun at the beaches as onshore flow prevails, but expect at least
partial clearing most days.
A strong ridge will redevelop over the far eastpac, west of ksfo
next week. The ridge will nose eastward across California midweek and may
flatten the marine layer and bring some warming, especially inland
about Wednesday before it weakens. Hard to say whether it will last
long though as another trough in the westerlies to the north digs southeast
across the northern rockies. The European model (ecmwf) solutions have been most
aggressive with this feature, turning it into a full, longwave
trough over the west by Saturday. The GFS ensemble mean generally
agrees, although the operational run is much weaker. With that in
mind, expect more relatively cool weather next weekend. The temp
grids have been blended to bias them cooler in the extended period
since this looks to be consensus.
160315z...coast/valleys...low clouds with bases 1200-1800 ft mean sea level
will continue to spread inland overnight, reaching kont and ksbd
after 09z. Local vis restrictions of 3-5 sm in br/haze in the valleys
and coastal slopes of the mountains obscured in clouds through
around 16z. Scatter out expected in the valleys after 16z and on the
coast after 18z.
Mountains/deserts...mostly clear with unrestricted vis through
Sunday. West winds with sfc gusts 25-35 kt will occur along the
mountain crests and Desert Mountain slopes and below the passes this
evening, weakening overnight. Areas of up/down drafts are possible
over and east of the mountains.
no hazardous marine conditions are expected through Thursday.
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.