-- Discussion containing changed information from previous version are highlighted. --
026
FXUS66 KMTR 231604
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
904 AM PDT Sun Jun 23 2024

...New UPDATE, MARINE...

.SYNOPSIS...
Issued at 237 AM PDT Sun Jun 23 2024

Somewhat cooler temperatures in the interior today, continuing into
the beginning of the work week with a slight cooldown midweek. Very
low chance of elevated convection and associated dry lightning in
the southern Central Coast.

&&

.UPDATE...
-- Changed Discussion --
Issued at 902 AM PDT Sun Jun 23 2024

Visibilities continue to improve over inland areas of the region and
therefore the Dense Fog Advisory for the Monterey Bay and areas
surrounding was allowed to expire at 9 AM PDT. However, if
encountering dense fog on area highways; slow down, use your
headlights, and leave plenty of distance ahead of you. Otherwise,
low clouds have retreated to the coast with clear sky conditions
inland. The ongoing forecast for the short term remains on track
with no updates anticipated this morning.
-- End Changed Discussion --

&&

.SHORT TERM...
(Today and tonight)
Issued at 237 AM PDT Sun Jun 23 2024

Skies remain generally clear throughout the region, save for stratus
that has developed around the Monterey Bay region, and stratus
development for the rest of the morning is limited to the coast and
potentially the North Bay valleys and northern SF Bay region. Low
temperatures tonight range from the low to mid 50s in the lower
elevations to the 60s to low 70s in the higher elevations. With the
upper level ridge moving off to the east, highs will be somewhat
cooler today, with highs in the upper 80s to mid 90s in the interior
valleys, perhaps close to 100 in the warmest spots, with highs in
the 70s expected across the Bayshore and the mid 50s to mid 60s
across the Pacific coast.

The main forecast issue continues to be the potential for elevated
convection over the southern sections of Monterey and San Benito
counties this afternoon and evening. A shot of mid-level moisture
will come into the region from the south, ahead of a weak upper
level trough. The latest 3km NAM forecast soundings for Paso Robles
continue to show a moistening low to mid layer and respectable lapse
rates. Below the moist layer, conditions remain dry, which will
hamper any precipitation from any cells that pop up, but will also
raise the risk of dry lightning, especially with MUCAPE levels above
1000 J/kg. All that said, the potential for any storms to develop
continues to be low, hovering around 10-15%. One factor that limits
storm potential is that the synoptic forcing remains to our north
and west, requiring any storms that do develop to be topographically-
driven. Confidence in any fire weather concerns remains too low to
message as a fire weather headline. The day shift will take another
look at the forecast as updated model output comes in.

&&

.LONG TERM...
(Monday through Saturday)
Issued at 237 AM PDT Sun Jun 23 2024

The mid-layer moisture continues to push through the region and will
push across the Bay Area on Tuesday. In addition to the mid- to
upper level clouds that will typically accompany the moisture, the
chance for elevated convection mainly across the Central Coast
remains through Tuesday, although as with Sunday, the chances are
very low. Interior temperatures will cool off on Wednesday and
Thursday, with highs in the 80s to the mid 90s, as an upper level
trough comes into the West Coast and promotes improved onshore flow.
CPC outlooks continue to suggest that temperatures above seasonal
averages will continue into the first week of July.

&&

.AVIATION...
(12Z TAFS)
Issued at 512 AM PDT Sun Jun 23 2024

Update: Confidence in stratus impacts away from the immediate
coast, barring the Monterey Bay region, has decreased further.
Have removed mention of stratus ceilings this morning from all
TAFs save MRY, where the TEMPO group remains for LIFR ceilings.
Monitoring the bank of stratus just off the coast of Monterey for
potential impacts to the terminal. Previous discussion is
reproduced below.

Generally clear skies across the region with the exception of a
patch of IFR/LIFR stratus and fog in the Monterey Bay region.
Satellite imagery is showing a bank of stratus offshore which could
impact the coastal region before sunrise. Elsewhere, confidence in
stratus impacts has decreased and have turned the prevailing
ceilings tonight into TEMPO groups to reflect this. Wherever stratus
does emerge, expect it to clear around 16-17Z. Breezy onshore winds
will set up in the afternoon and evening. Some model output suggests
that stratus will return to the coast, the North Bay valleys, the
northern SF Bay, and the Monterey Bay region this evening. Of these,
the highest confidence for impacts is at the coast and around
Monterey Bay.

Vicinity of SFO...Confidence in stratus impacts this morning has
decreased at the terminal; therefore, the prevailing ceiling has
been modified to a TEMPO group. If stratus does form or move over
the terminal, expect it to clear out around 16Z. Breezy west-
northwest winds with gusts up to 20 knots will develop in the
afternoon and persist into the evening. Low confidence for any
stratus impacts this evening into Monday morning.

SFO Bridge Approach... Similar to SFO.

Monterey Bay Terminals... MRY and SNS had cleared out earlier
tonight after getting ceilings, but the bank of stratus remains over
the rest of Monterey Bay, and dense fog has subsequently been
reported over SNS. Have kept ceilings at both terminals with the
difficult forecast situation limiting confidence for the rest of the
morning. Current expectation is for the ceilings to scatter out
around 16-17Z, with breezy onshore winds up to 10-15 knots expected
this afternoon and evening. Stratus is expected to redevelop this
evening, with model output suggesting the possibility of dense fog
at MRY towards the end of the TAF period.

&&

.MARINE...
-- Changed Discussion --
(Today through Friday)
Issued at 902 AM PDT Sun Jun 23 2024

Hazardous conditions for small crafts persist across the northern
coastal waters through the early work week. Strong northwest to
northerly winds continue over the northern coastal outer waters.
Fresh gusts remain possible over the southern outer waters and
portions of the northern interior coastal waters. Winds will
strengthen over the northern coastal waters today with strong to
near gale force gusts possible through Monday morning. Significant
wave heights over the northern waters will gradually build to
10-11 feet Sunday into Monday before beginning to diminish
Tuesday.
-- End Changed Discussion --

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
CA...None.
PZ...Small Craft Advisory until 9 PM PDT this evening for Pt Arena to
     Pt Reyes 0-10 nm-SF Bay N of Bay Bridge.

     Small Craft Advisory until 9 AM PDT Tuesday for Pt Arena to Pt
     Reyes 10-60 NM.
-- End Changed Discussion --

&&

$$

UPDATE...RGass
SHORT TERM...DialH
LONG TERM....DialH
AVIATION...DialH
MARINE...Kennedy

Visit us at www.weather.gov/sanfrancisco

Follow us on Facebook, Twitter, and YouTube at:
www.facebook.com/nwsbayarea
www.twitter.com/nwsbayarea
www.youtube.com/nwsbayarea