Scientific Forecaster Discussion
fxus66 ksgx 180353
Area forecast discussion
National Weather Service San Diego California
851 PM PDT Sat Aug 17 2019
cooler weather this weekend will turn very hot inland again next
week as high pressure builds over the southwest. At the same time,
nocturnal marine cloud and fog formation will likley be confined to
Discussion...for extreme southwestern California including Orange...
San Diego...western Riverside and southwestern San Bernardino
At sunset, some fleecy high clouds were spreading northeast across
socal, as marine stratus was gathering over the coastal waters and
edging inland. Moderate onshore sfc pressure gradients were
supporting peak wind gusts of 35-50 miles per hour again near the passes, and
20-25 miles per hour most other wind-prone areas in the mts/deserts. Our 00z
Miramar sounding had about a 7c inversion based near 2k feet mean sea level. Some
cooling had occurred in the mid-levels with stronger SW flow.
The forecast is on track for another pleasant day on Sunday with
daytime temperatures running 3-8f below mid-Summer normals most
areas. No forecast changes.
From previous discussion...
Mostly sunny skies and cooler than average weather are with US this
afternoon. A deepened marine layer will again allow low clouds and
fog to push ashore relatively early this evening and push inland
overnight. Clouds could nearly fill the coastal basin tonight much
as they did last night. Low pressure aloft, responsible for our
deeper marine layer, will lift out and high pressure from the east
will gradually press down over the southwest over the next few days.
That will bring US a noticeable warming trend starting Monday that
will peak in a heat wave Wednesday and Thursday very similar to the
heat wave we had this past week. High temperatures through Monday
will come in a little below average for most areas, but will climb
above average inland by Tuesday and 5-10 degrees above average on
Wednesday and Thursday, the projected hottest days. The high
pressure aloft weakens ever so slightly Thursday into next weekend.
Temps will begin a modest decrease, although it will still be plenty
hot inland. Monsoon moisture begins to show itself toward next
weekend, but nothing to really forecast about yet. You may be
hearing about some model guidance bringing a hurricane up the West
Coast of Mexico. There is a forming tropical depression south of
Guatemala that is shown by some guidance to grow into a hurricane,
then move west and northwest along the Mexico coast. It parallels
Baja California early the following week (around 26 aug). It's
something interesting to watch, but there's little if any chance of
impact on socal weather.
180345z...coast/valleys...bkn-ovc stratus will continue to spread
along the coast this evening and up to 30 miles inland by 11z sun,
including west and south parts of the inland Empire. Bases will be
1500-1900 ft mean sea level with tops to 2100 ft msl, with higher terrain
locally obscured. Local vis of 1-3 miles will occur in the valleys
08z-16z sun. Valleys will mostly clear 15z-16z sun with coastal
areas clearing 16z-18z. Stratus could be a little lower in height
Sunday night as it spreads inland.
Mountains/deserts...scattered clouds at/above 20000 ft mean sea level and
unrestricted vis will continue through Sunday evening. West winds
will locally gust 25-35 kt from the mountain crests east through the
desert foothills and near San Gorgonio Pass through 12z sun. No
impacts are expected at kpsp and ktrm.
no hazardous marine conditions are expected through Thursday.
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
California...excessive heat watch from Tuesday morning through Thursday
evening for apple and Lucerne valleys-Coachella Valley-San
Diego County deserts-San Gorgonio Pass near Banning.