388
FXUS66 KMTR 242043
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
143 PM PDT Mon Jun 24 2024

...New SYNOPSIS, SHORT TERM...

.SYNOPSIS...
Issued at 142 PM PDT Mon Jun 24 2024

Temperatures near to slightly above seasonal averages with a slight
cooldown midweek. Very low chance of high-based convection and
associated dry lightning in the Central Coast today. The threat will
shift northward into the Bay Area and North Bay tonight into Tuesday
evening.

&&

.SHORT TERM...
(This evening through Tuesday)
Issued at 142 PM PDT Mon Jun 24 2024

We continue to see a small threat (10-15%) for high-based convection
across Monterey and San Benito County this afternoon and that threat
will shift northward throughout the night and into tomorrow morning,
potentially into the afternoon/evening as well. This is as mid-level
moisture is being advected in from the south and will move across
the entire Bay Area through Tuesday evening with forecast MUCAPE
between 100-300 J/kg. Mid-level moisture is the most certain
ingredient, with a plume of moisture migrating northwards with PWAT
values up to 1-1.25". For context, if those values were reported at
our upper air site at Oakland airport, those precipitable water
values would be at or above the 90th percentile value for all
observed soundings at this time of year. The main impact if
convection does develop would be the possibility for dry lightning
setting off grass and shrub fires, but this is a "low confidence-
high impact" type of event at this stage.

Otherwise, temperatures are expected to be near seasonal averages
for coastal areas and slightly above for the interior the next
several days with most areas away from the coast only getting to
Minor HeatRisk.

&&

.LONG TERM...
(Tuesday night through Sunday)
Issued at 1243 AM PDT Mon Jun 24 2024

Wednesday sees an upper level trough move in which will push the
moisture out of our region, and herald a gradual cooling trend in
temperatures for the interior regions. By the end of the week,
temperatures across the interior will top out at around 90 in the
warmest spots, with most of the inland valleys seeing temperatures
within the 80s. Towards the beginning of July, model ensemble
clusters are indicating a couple of ridges approaching the West
Coast, with early indications of a warming trend towards the end of
the 7-day forecast.

&&

.AVIATION...
(18Z TAFS)
Issued at 1056 AM PDT Mon Jun 24 2024

VFR across the board with IFR conditions returning along the Central
Coast overnight. The marine layer remains compressed to
approximately 1000 feet this morning with little change expected
during the TAF period. Stratus should stay confined directly along
the coast and Central Coast regions with mid-level moisture bringing
scattered to broken mid-level and upper level clouds this
afternoon/overnight. Slight chance of thunderstorms continues along
the Central Coast but confidence remains low that thunderstorms will
impact either MRY or SNS. Onshore west to northwest flow continues
for most airports except for STS and APC where more southerly to
southwesterly winds are expected to prevail. Moderate winds between
10 to 18 knots are expected this afternoon before lighter, more
variable winds return overnight.

Vicinity of SFO...VFR through the TAF period. Moderate confidence
that stratus will not reach SFO with the more compressed marine
layer keeping stratus directly confined along the coastline.
Moderate west to northwest winds continue through the afternoon and
evening before weakening overnight. Ensemble guidance indicated
slight potential for gusts between 20 to 25 knots this afternoon.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR becoming IFR overnight. Moderate
onshore flow persists through the afternoon/evening before lighter,
variable winds return overnight. Low to moderate confidence that
broken to overcast IFR CIGs will develop overnight with model
consistency increasing after 08-11Z for both MRY and SNS. A slight
chance of thunderstorms in the vicinity of MRY and SNS remains
possible but confidence is still too low to include in TAFs. Will
continue to monitor for any thunderstorms that do develop and update
as needed.

&&

.MARINE...
(Today through Saturday)
Issued at 910 AM PDT Mon Jun 24 2024

Hazardous conditions for small crafts persist across the northern
coastal waters through early week. Fresh to strong north to
northwest winds continue over the northern coastal waters.
Moderate northwest winds continue over the southern coastal waters
with the occasional fresh gust possible over the outer waters.
Significant wave heights over the northern waters will build to
10-11 feet through today before wave heights abate below 10 feet
by Tuesday. Widespread fresh to strong winds are expected to
return over the coastal waters by late week with wave heights
gradually building to 10 feet across portions of the northern
coastal waters.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 9 AM PDT Tuesday for Pt Arena to Pt
     Reyes 10-60 NM.

&&

$$

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

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