Forecast Discussions mentioning any of "ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 05/17/23

Area Forecast Discussion...UPDATED

National Weather Service San Francisco CA

 843 PM PDT Tue May 16 2023

...New UPDATE...

.SYNOPSIS...
Issued at 151 PM PDT Tue May 16 2023

Above average temperatures will persist into Wednesday,
especially across the interior. Meanwhile, coastal areas will hold
near to slightly below normal as a result of the typical ebb and
flow of coastal stratus. Otherwise, dry weather conditions will
prevail through the forecast period with slight cooling late week
and into the upcoming weekend.

&&

.UPDATE...
Issued at 842 PM PDT Tue May 16 2023

Right on cue - the sun began to set and the coastal stratus begin
its march back inland. SFO-SAC gradient has increased to 2.4 mb,
which is moderate on strength. The onshore flow is also
represented by some gusty winds: SFO 30kts and OAK 27kts.
Satellite imagery shows stratus is through the Golden Gate, into
the North Bay Valleys, and moving up the Salinas Valley. Despite
the inland movement the marine layer depth is still rather shallow
at roughly 1,000 feet. Expect the stratus to move farther inland
as the night progresses. Given the more compressed marine layer
fog will be more likely tonight, but not expecting widespread
dense fog. Current forecast remains on track and no update is
needed.


&&

.SHORT TERM...
(This evening through Wednesday)
Issued at 151 PM PDT Tue May 16 2023

Marine stratus continues to blanket the west and northwest facing
coastal areas this afternoon while sunny sky conditions developed
elsewhere. Thus, temperatures are holding in the upper 50s to
lower 60s at the coast with upper 70s to lower 80s reported
inland. Expecting a few degrees of additional warming through the
afternoon with the warmest interior locations peaking in the upper
80s to near 90 deg F. With the well defined marine layer in
place, stratus will once again return to the coast and adjacent
valleys this evening before penetrating well inland overnight.
Look for a near repeat for Wednesday as weak ridging persists over
the region.

&&

.LONG TERM...
(Wednesday night through next Monday)
Issued at 151 PM PDT Tue May 16 2023

The ebb and flow of coastal stratus and/or fog will persist into
Wednesday night into Thursday morning. Meanwhile, daytime
temperatures will cool by a few degrees in response to weak
troughing over the eastern Pacific. This will work to increase
onshore flow and shift the ridge of high pressure further to the
east. As such, afternoon temperatures will peak in the upper 70s
to mid 80s across the interior with upper 50s to lower 70s closer
to the coast/bays. By Sunday into Monday, the trough will shift
into the Pacific Northwest and far northern California. This will
result in continued near to slightly above normal temperatures
region-wide while any chance of precipitation remains well north
of the San Francisco Bay Area.

&&

.AVIATION...
(00Z TAFS)
Issued at 500 PM PDT Tue May 16 2023

Terminals are currently VFR, but low clouds are lurking along the
coast. Still seeing some breezy onshore winds, but there has been
a downward trend over the last few hours. The clouds along the
coast will come inland tonight: Monterey Bay Terminals 04-06Z and
SFO/OAK 09-10Z with IFR conditions. Low cigs will linger through
mid-morning impacting the morning rush. VFR expected for Wednesday
afternoon.

Vicinity of KSFO...VFR through the evening with breezy NW winds
prevailing. Low clouds will feed through the Golden Gate this
evening and remain in the Gap, but not impact SFO/OAK before 06Z.
Confidence increases for stratus intrusion after 06Z with highest
confidence 08-10Z. Cigs that do impact SFO/OAK will dissipate by
17Z.

SFO Bridge Approach..Slightly later on time of arrival 10-12Z.
Given the shallow nature some of the hi-res models show more
patchy stratus impacting the approach zone Wednesday morning so
aircraft may be able to

Monterey Bay Terminals...IFR returning this evening 04-05Z then
persisting mid-late morning Wednesday.

&&

.MARINE...
(Today through Sunday)
Issued at 240 AM PDT Tue May 16 2023

A weak surface high pressure system will remain located over the
offshore waters while a surface thermal low pressure trough
remains stationary over interior California. Thus, northwesterly
winds will continue across the coastal waters while westerly winds
prevail across the bays, strongest each afternoon and evening.
Moderate period mixed seas prevails through the week.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 9 PM PDT this evening for PZZ530.

     Small Craft Advisory from 3 PM to 9 PM PDT Wednesday for PZZ530-
     560.

     Small Craft Advisory until 3 AM PDT Wednesday for PZZ540-560-565-
     570-575.

     Small Craft Advisory from 3 PM Wednesday to 3 AM PDT Thursday
     for PZZ540-565.

     Small Craft Advisory from 9 PM Wednesday to 3 AM PDT Thursday
     for PZZ570.

&&

$$

UPDATE...MM
SHORT TERM...RGass
LONG TERM....RGass
AVIATION...MM
MARINE...RGass

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