National Weather Service Forecast Discussion

Dicussion provided by the National Weather Service Forecast Office located in San Diego, California

000
FXUS66 KSGX 282122
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
122 PM PST Sat Nov 28 2020

.SYNOPSIS...
Weak offshore flow and low humidity will continue through early
next week. Chilly overnight temperatures are expected each night
in the wind sheltered valleys with some patchy frost possible.
High pressure aloft will bring slight warming through Tuesday.
Another Santa Ana event appears likely towards the middle of the
week.

&&

.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...

At 1 PM, skies were crystal clear across Southern California. High
temperatures today will be slightly below normal in the mountains
and deserts, and a few degrees above normal for the coast and
valleys. Another chilly night is in store for inland areas. Patchy
frost is possible in the Inland Empire and San Diego valleys,
where temperatures will drop into the low to mid 30s.

Weak offshore winds will continue each night and morning, as well
as low humidity for inland areas. Elevated fire weather
conditions will continue for the mountains and valleys through
much of the week due to the low humidity and offshore flow.

Temperatures will continue to warm through the weekend and into
early next week as weak offshore flow prevails, with Monday and
Tuesday as the warmest days west of the mountains. Daytime highs
will range from 5 to 10 degrees above normal west of the
mountains, and near normal in the mountains and deserts. Offshore
flow should be strong enough to keep low clouds and fog from
developing for much of the week. Clear skies and dry air will
result in chilly overnight temperatures and patchy frost for wind-
sheltered locations each morning through Tuesday.

Uncertainty exists regarding the midweek Santa Ana event,
although the 12Z models have come into slightly better agreement.
The EC ensemble shows an upper level low dropping down into the
Four Corners Region on Tuesday, producing at least a moderate
strength Santa Ana wind event and periods of critical fire weather
conditions. The GEFS is a bit slower with the upper level low and
takes it on a more northeasterly track than the EC ensemble,
which would delay the onset of winds until sometime Wednesday into
Thursday. The GEFS has been fairly consistent with timing and
strength the last few runs, while the EC ensemble has deviated a
bit from run to run. We will continue to monitor these trends, and
hopefully timing and strength will become more clear in the next
day or two.

&&

.AVIATION...
282000Z...Periods of locally gusty north to east winds of 20-30 kts
will continue mainly through mountain passes and through canyons
through Sunday morning. Otherwise, VFR conditions with clear skies
and winds 8 kts or less at all the terminals through Sunday.

&&

.MARINE...
No hazardous marine conditions expected through Thursday.

&&

.FIRE WEATHER...
Offshore winds have largely diminished this afternoon in the mountains
and valleys, but some localized gusts of 25-35 mph could occur
through this evening.

Weak offshore flow will continue each night and morning through
early next week, with gusts generally 25 mph or less. Humidity
will continue to be low, around 10 to 15 percent in the mountains
and valleys through much of the week. Winds and low humidity will
result in elevated fire weather conditions through Monday.
Another Santa Ana event, at least moderate in strength, will occur
mid week, with a period of critical fire weather conditions
possible. Timing remains a bit uncertain, but it looks to be
sometime between Tuesday and Thursday. Weaker offshore flow and
elevated fire weather conditions appear likely for late next week.

&&

.SKYWARN...
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...NONE.
&&

$$

PUBLIC/FIRE WEATHER...Connolly
AVIATION/MARINE...Moreland

NWS SGX Office Area Forecast Discussion