Area Forecast Discussion
Issued by NWS San Diego, CA
FXUS66 KSGX 280947
Area Forecast Discussion
National Weather Service San Diego CA
247 AM PDT Fri Oct 28 2016
A Pacific low pressure system will bring showers and perhaps a few
thunderstorms today. A moist atmosphere will continue Saturday
that will result in a few showers mainly in the mountains. Another
low pressure system will bring a better chance of showers on
Sunday, along with brisk winds in the mountains and desert. Cool
weather will continue for Halloween and the first day of November.
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
A pretty organized comma cloud and associated band of rain across
central California is slowly working its way into Southern
California this morning. There are some thunderstorms embedded in
this band as well in Santa Barbara County. Rainfall has not been
too heavy but beneficial for that thirsty part of the state.
Showers will arrive in LA and Orange Counties right in time for
the morning commute. The models and the associated forecast has
backed off a bit as far as rainfall amounts and threat of
thunderstorms. There is also better consensus between models that
raises our confidence as we watch the system approach. The rain
band will weaken as it drags eastward, giving Orange County and
the northern Inland Empire a glancing blow. Expect about a quarter
to a half inch of rain and the threat of thunderstorms will be
confined to those areas. San Diego and Riverside Counties will get
from zero to about a quarter inch highest in the north. There is
a threat of flash flooding on the Blue Cut burn area around Cajon
Pass because it lies in the bullseye of greatest forecast rainfall
amounts of just over an inch. The weakening system will zip out of
the area this afternoon and evening, but will leave behind some
residual moisture. That will be just enough to warrant the
forecast of a few showers mainly in the mountains on Saturday, but
also slightly possible in Orange County and the inland valleys. On
Sunday a stronger trough of low pressure moves through northern
California. In Southern California it will make do with the
leftover moisture and produce some showers from the coast to the
mountains. This system has a little more energy for producing
strong westerly winds in the mountains and deserts. Right now it
appears some gusts would exceed 40 mph. That system exits east,
but some low level moisture remains. Although we don`t expect rain
that day, we`ll have some clouds and we`ll be in a cool air mass
for a rather cool Halloween. Some form of weak trough will meander
around the region around the middle of next week. Past model runs
had shown rain, but right now it appears dry but cool for the
start of November.
280935Z...SCT-BKN cloud layers at/above 9000 ft MSL this morning
gradually lowering to around 5000 ft MSL by Sat morning. Between 15Z-
29/00Z...-SHRA/isolated TSRA moving E over the area with local CIGs
800-1500 ft MSL and 1-3 SM vis. Best chance of precip will be in
Orange County...far W Riverside County...and SW San Bernardino
County...with only small chances in San Diego County. Showers
diminishing after 00Z. Coastal mountain slopes will be obscured in
clouds/showers this afternoon through Sat morning.
A weak cold front moving through the coastal waters will bring a
chance of showers and perhaps an isolated thunderstorm late this
morning through the afternoon. Light showers are possible again
Saturday afternoon into Sunday.
There is a slight chance of thunderstorms at the beaches today,
mainly in Orange County. A moderate period south swell from post-
tropical cyclone Seymour will bring elevated surf and strong rip
currents today and Saturday.
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
CA...Flash Flood Watch until 2 PM PDT this afternoon for San
Bernardino County Mountains.