Scientific Forecaster Discussion
fxus66 ksgx 182027
Area forecast discussion
National Weather Service San Diego California
130 PM PDT Mon Jun 18 2018
this afternoon will be mostly sunny but continued cool as the low
pressure trough over the west weakens. High pressure aloft will
build Tuesday through Friday and result in a return to hot weather
in the deserts and some of the inland valleys, especially starting
Wednesday. The night and morning low clouds will mostly just be
patchy. Slight cooling will occur over the weekend as the high
weakens. Otherwise, dry conditions will prevail the rest of this
week and early next week.
Discussion...for extreme southwestern California including Orange...
San Diego...western Riverside and southwestern San Bernardino
Skies were mostly sunny except for some lingering low clouds, mostly
in Orange County. Temperatures were 5-10 deg f below normal, with
mostly 70s west of the mountains, and mostly lower to mid 90s in the
The biggest weather impact this week will be the desert and far
inland valley heat, especially Wednesday through Friday. As the
upper low over the west gradually weakens and lifts northeast
towards the northern rockies/northern plains Tuesday, we will have a
high pressure ridge forming just off the Southern California coast,
with the high shifting east to so-cal/southwest Arizona Wed/Thu.
As would be expected at this time of year, the high will bring hot
weather inland, with temps at seasonal levels Tuesday, then 5-10 deg
f above seasonal levels Wednesday through Friday for most inland
areas. This means 110-114 deg f in the lower deserts, which is near
or just below critical levels. The humidity will be low, both at the
surface and aloft, so nighttime minimum temps will mostly be in the
70s, except a few 80s in thermal belts. For now, no excessive heat
watch will be issued for the deserts, but we will watch this
closely, and if it appears 115 deg f temps will occur beyond just a
few localities, we will definitely consider a watch. As the upper
high shifts south of the US-Mexico border this weekend due to an
upper low diving south across The Rockies and eastern parts of the
Great Basin, that should bring a few degrees of cooling inland.
Monsoonal moisture stays well to the southeast through at least
early next week.
182010z...coast/valleys/coastal mountain slopes...few-sct low clouds
this afternoon, with bases 2500-4000 ft mean sea level and tops to 4500 ft mean sea level.
Low clouds should begin to redevelop along the coast between 03z and
06z Tue, with bases 1500-2000 ft mean sea level and tops to 2500 ft mean sea level. Clouds
expected to increase in coverage overnight and cigs to lower. Areas
of reduced visible are likely where clouds and terrain intersect. Expect
clearing to the coast between 16z and 18z Tue.
Desert Mountain slopes/deserts...mostly clear with unrestricted visible
through tonight. Locally gusty northwest winds will weaken overnight.
west northwest winds gusting near 20 kt this afternoon and evening.
Otherwise, no hazardous marine weather is expected through Friday.
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.