Scientific Forecaster Discussion
fxus66 ksgx 272041
Area forecast discussion
National Weather Service San Diego California
200 PM PDT Mon Mar 27 2017
low pressure aloft will bring gusty west winds to the mountains and
deserts through early this evening. Otherwise, partly cloudy skies
will prevail west of the mountains with temperatures a little below
normal. High pressure building into the Great Basin will bring
locally gusty northeast winds below passes and canyons tonight and
Tuesday. Mostly clear skies will prevail Tuesday and Wednesday with
warmer weather. Another low pressure system will move by to the
northeast Thursday and Friday and will bring strong westerly winds
to the mountains and deserts and cooler weather. Fair and warmer
weather will prevail next weekend under high pressure, with another
low pressure system possibly bringing cooling again early next week.
Discussion...for extreme southwestern California including Orange...
San Diego...western Riverside and southwestern San Bernardino
Partly cloudy skies prevailed west of the mountains with a small
amount of lingering fog along the coastal mountain slopes. The
marine layer was generally 5000-6000 feet deep which resulted in
the slow clearing in the valleys and foothills. West winds were
strong in the mountains and deserts with a 59 miles per hour gust at White
Water west just east of San Gorgonio Pass at mid-morning, though
most windy areas had peak gusts between 40 and 50 miles per hour today.
Local WRF model, hrrr and cansac-WRF show these winds continuing
through around 7 PM tonight, then weakening somewhat as offshore
The low pressure trough axis was over so-cal with two main waves but
not enough moisture for precipitation in our forecast area. The
trough will shift to The Four Corners tonight with rather tight
height gradients under northwest flow behind the trough. A surface high
will build over northern Nevada late tonight and Tuesday and
contribute to moderate offshore flow, with surface mslp gradients
around 10 mb from west-central Nevada to San Diego, though very much
northerly in orientation versus northeasterly. That will result in
winds below east-west ridges, mainly San Bernardino County, with some
winds in the Santa Ana Mountains. Mountain waves will not be
particularly strong, with most of the winds below the crests but not
as much in the valleys, except briefly late Tuesday morning after
surface heating results in some mixing. Overall, peak gusts will be
45-60 miles per hour. San Diego County will see very little of this wind due to
the northerly gradients. Winds will mostly decrease by Tuesday mid-
afternoon. By Tuesday morning, most areas will be clear, so that
combined with the cold low having exited to the east, will result in
5-10 deg f warming in most areas to slightly above normal. Wednesday
should be quite warm with temps around 10 deg f above seasonal
normals, which means a lot of 80s in the inland Empire and far
inland valleys of San Diego County.
Models continue to have a deep low tracking from far northern
California to far northern Arizona from Thursday to Friday. This
inland track will most likely keep our area dry, but the mountains
and deserts could have strong winds, especially late Thursday and
Thursday night. Temperatures will decrease, though just to near or
very slightly below normal by Friday. The low will track east over
the weekend with fair weather to follow. Offshore flow will be
rather weak though. Temps will increase again to 5-10 deg f above
normal by Sunday. Another inland closed low could drop down from the
north early next week.
272040z...sct-bkn025-035 tops 5000 ft through 03z. An intermittent
ceiling near 3000 feet is possible at ksan and kcrq through 12z
Tuesday. Mostly clear skies Tuesday.
Strong westerly winds 20-40 kt over the mountains and into some of
the deserts tonight with areas of strong up/downdrafts and low level wind shear over
and east of the mountains. The winds shift northeasterly after 04z
Tuesday, surfacing in the inland Empire through 23z impacting kont,
ksbd and possible ksna with strong up/downdrafts and low level wind shear.
a Small Craft Advisory is in effect for strong northwest winds and
rough seas through Tuesday. Northwest winds will increase again
Thursday and continue through Friday leading to more choppy seas and
hazardous boating conditions.
west to northwest swells will bring elevated surf of 3 to 6 feet
most of the week with occasional sets to 7 feet.
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
California...Wind Advisory until 10 PM PDT this evening for apple and Lucerne
valleys-San Diego County deserts-San Diego County mountains.
Wind Advisory from 10 PM this evening to 2 PM PDT Tuesday for
San Bernardino and Riverside County valleys-the inland
Empire-Santa Ana Mountains and foothills.
Wind Advisory until 2 PM PDT Tuesday for Riverside County
mountains-San Bernardino County mountains-San Gorgonio Pass
Pz...Small Craft Advisory until 8 PM PDT Tuesday for coastal waters
from San Mateo Point to the Mexican border and out to 30 nm-
waters from San Mateo Point to the Mexican border extending
30 to 60 nm out including San Clemente Island.