677
FXUS66 KMTR 241625
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
925 AM PDT Tue Sep 24 2024

...New UPDATE, MARINE...

.SYNOPSIS...
Issued at 229 AM PDT Tue Sep 24 2024

Heat Advisory in effect for interior East Bay through this evening.
Temperatures on Wednesday cool to near the seasonal averages,
slightly warming by Friday.

&&

.UPDATE...
Issued at 921 AM PDT Tue Sep 24 2024

Stratus coverage this morning is limited to the immediate coastal
regions south of Pigeon Point. Another relatively warm day is
still on track with clear skies across most of the region. The
Fort Ord profiler, which showed the marine layer completely eroded
away yesterday afternoon, is now showing the beginnings of its
return, which is consistent with stratus returning inland tonight
as low temperatures return to around the seasonal average. No
updates needed to the forecast.

DialH

&&

.SHORT TERM...
(Today and tonight)
Issued at 229 AM PDT Tue Sep 24 2024

Another warm day in store across the region this afternoon, yet
slightly cooler than yesterday. As such, a Heat Advisory remains in
effect for the interior East Bay until 8 PM this evening due to
widespread moderate HeatRisk with temperatures in the mid 90`s to
near 100 degrees. Elsewhere, expecting temperatures to range from
the low-to-upper 90`s in the region`s warmest interior spots, mid
80`s to lower 90`s around the San Francisco Bay Shoreline, and upper
60`s to mid 80`s as you get closer to the coast.

Here`s a reminder about heat safety:

* Stay hydrated and drink plenty of fluids.
* Wear lightweight, light-colored clothing.
* Reduce time spent outdoors or stay in the shade.
* Never leave people or pets unattended in vehicles.
* Use sunscreen if going to the coast or the pool.

Tonight, expecting a significant cool-down especially in the higher
terrain as high pressure aloft shifts east with lows dropping into
the 60`s. In the lower elevations, generally expecting temperatures
in the 50`s to lower 60`s in the warmer interior valleys. Low clouds
will also spread inland as the marine layer deepens to around 1,000
feet.

&&

.LONG TERM...
(Wednesday through Monday)
Issued at 229 AM PDT Tue Sep 24 2024

A more robust cool-down is anticipated for Wednesday as the ridge
moves farther east and troughing builds over the West Coast.
Temperatures on Wednesday cool to or slightly below seasonal
averages. A gradual warming trend is then expected through Friday as
a zonal pattern sets up to our north and weak upper level troughs
move through to our south and southwest. The CPC outlooks leans
toward above average temperatures and below average precipitation
through the first week in October.

&&

.AVIATION...
(12Z TAFS)
Issued at 428 AM PDT Tue Sep 24 2024

The marine layer remains compressed and varied in depth from 400
to 600 feet along the north Central Coast to sea level along the
San Mateo county coastline northward to the coastal North Bay. A
coastally trapped southerly wind reversal recently developed with
the SMX-SFO pressure gradient varied between 1 mb and 2 mb. Satellite
imagery shows coastal stratus and fog /VLIFR-IFR/ advancing northward
and trying to advance into the northern Salinas Valley. In general
forecast models are under-forecasting the SMX-SFO gradient at the
present time and indicate the SMX-SFO strengthening today. A coupling
to the mid-upper level low to our southwest may help speed up the
southerly wind reversal pattern through today and tonight.

Vicinity of SFO...VFR. Light and variable wind becoming northwest
10 to 14 knots this afternoon and evening.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Coastal stratus and fog /VLIFR-IFR/ are
advancing northward with some mixing out of the leading edge of
stratus and fog. A coastally trapped southerly wind reversal is
developing, however drier air on light southeast winds vicinity
KSNS and KMRY are at least briefly interrupting fog development.
In general since meso-scale models are currently under-forecasting
the SMX-SFO gradient (and SNS-SJC gradient) and forecast a
strengthening of these gradients today, expect a general increase
in coastal stratus and fog /VLIFR-IFR/ during the 12z TAF period.
Diurnal mixing today will help lift conditions to MVFR-VFR, but
expect an early return of stratus ceilings this evening first to
KSNS then KMRY, typically the timing for southerly wind reversals.

&&

.MARINE...
(Today through Sunday)
Issued at 921 AM PDT Tue Sep 24 2024

Light to locally moderate northwesterly flow will prevail over
the coastal waters. Strongest winds will be north of Point Reyes
over the outer waters. Breezy onshore flow will continue through
the West Delta each afternoon. A passing disturbance over the
Pacific Northwest will result in stronger northerly flow and
builds seas Wednesday night into Thursday.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory until 8 PM PDT this evening for CAZ510-515.

PZ...None.
&&

$$

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

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