Forecast Discussions mentioning any of "ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 12/01/21

Area Forecast Discussion

National Weather Service San Diego CA

 121 PM PST Tue Nov 30 2021

.SYNOPSIS...
Through Wednesday, weak Santa Ana winds for inland areas and areas
of dense fog at the coast. Onshore flow is expected to return
Thursday, increasing low cloud and fog coverage into portions of the
valleys and bringing cooler temperatures inland through Saturday.
Sunday and Monday another round of gusty Santa Ana winds expected,
with warm, dry conditions.

&&

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

Key Points:
*Weak Santa Ana winds today and Wednesday.
*Areas of dense fog near the coast tonight into Wednesday morning.
*More Santa Ana winds, with warm and dry conditions Sunday and
Monday.

Fog has cleared from the coast this afternoon, leaving mostly clear
skies. Areas of dense fog are expected at the coast overnight into
Wednesday morning. There remains uncertainty surrounding how
widespread the dense fog will be. Aircraft soundings from KSAN this
afternoon show the marine layer has maintained a depth of around
2500 ft. It is likely the lowest visibilities tonight into Wednesday
morning will be near the mesas and other higher coastal terrain
tonight with visibilities at sea level not quite as low as Monday
night into this morning.

Weak Santa Ana winds, with hot and dry conditions will continue
through Wednesday. Peak wind gusts of 40 to 45 mph will occur
through passes. Winds will become more widespread into San Diego
County on Wednesday with stronger gusts 35 to 40 mph. Temperatures
Wednesday will be 10 to 15 degrees above average in the Inland
Empire, eastern valleys of San Diego County, and in the mountains
and deserts. Temperatures will be a little cooler near the coast and
western valleys where the marine layer influence is higher.

Cooler conditions expected for Thursday with the return of onshore
flow. High temperatures will be around 5 degrees cooler for the
coast and valleys and a few degrees cooler for the mountains and
deserts. Cooling will continue to spread inland through Saturday. By
Saturday high temperatures will be near average at the coast and
about 5 to 10 degrees above average for inland areas. Night and
morning low clouds and fog will spread into portions of the valleys.

Another round of Santa Ana winds expected Sunday and Monday,
bringing warmer and drier conditions with stronger and gusty
northeast winds. ECMWF ensemble gusts for Ontario range from weak to
the lower end of moderate strength. The ECMWF Extreme Forecast Index
is keying more on the warming than the winds with high temperatures
reaching the 80th to 90th percentile on Monday for inland coastal
areas into the western valleys.

&&

.AVIATION...
302120Z...Coast...Patchy low clouds and fog at some beaches this
afternoon. Low clouds and fog increasing in coverage after 02Z and
spreading up to 10 miles inland overnight, although coverage is
expected to be less than last night. Expect BKN-OVC 100-300 ft after
04Z with areas of fog reducing vis to 1-3 miles. Areas of vis below
1 mile expected 07Z-16Z. Clearing to the beaches likely 17Z-19Z.

Valleys, Mountains and Deserts...Clear with unrestricted vis
through Wednesday.

&&

.MARINE...
Areas of fog with visibility 1 nautical mile or less could return
tonight into Wednesday morning. Otherwise, no marine weather hazards
are expected through Saturday.


&&

.FIRE WEATHER...
Weak Santa Ana winds will bring gusty northeast to east winds and
warm, dry conditions through Wednesday. Peak wind gusts will be
40 to 45 mph near the coastal slopes of the mountains and below
passes and canyons. Lowest daytime humidity falling to around 15
percent for the mountains and valleys. Expect elevated fire
weather conditions for the mountains and valleys through
Wednesday.

Thursday through Saturday, onshore flow will spread cooling and
higher coastal humidity inland. Another round of Santa Ana winds
expected Sunday and Monday with warm, dry conditions and gusty
northeast to east winds near the coastal slopes of the mountains and
below passes and canyons. Elevated to near critical fire weather
conditions are possible for the mountains, valleys, and inland
Orange County.

&&

.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...CO
AVIATION/MARINE...PG