907
FXUS66 KMTR 171759
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
1059 AM PDT Mon Jun 17 2024

...New AVIATION, MARINE...

.SYNOPSIS...
Issued at 158 AM PDT Mon Jun 17 2024

Red Flag Warning remains in effect for the North Bay Interior
Mountains from 11 AM to 8 PM Monday. Dry and breezy conditions
continue into Monday night. Better onshore flow and moisture
return by midweek. Another warming trend on the way for the
upcoming weekend.

&&

.UPDATE...
Issued at 952 AM PDT Mon Jun 17 2024

Forecast remains on track, with elevated fire weather concerns for
today across our region, and especially the North Bay Interior
Mountains, where a Red Flag Warning is in effect until 8pm PDT
tonight for gusty north winds up to 30 MPH and min RH values as
low as 10 percent.

&&

.SHORT TERM...
Issued at 158 AM PDT Mon Jun 17 2024
(Today and tonight)

Short term weather impacts will be mainly Fire Weather focused.
For specific details see the Fire Weather Section below. Simply
put, dry northerly winds and lack of marine layer continue to
bring elevated fire weather concerns to the region. The longwave
pattern currently shows an upper low dropping into the Great
Basin. The associated upper level trough will sweep through
NorCal early Monday. The passing upper trough will do two things:

shift winds and usher in dry air. Northwesterly flow currently
being observed will shift more northerly to northeasterly early
Monday morning. This will be most pronounced above 1,000 feet,
especially over the interior North mts and East Bay hills. The
shifting winds will usher in much drier air. RH values could be as
much as 10-20% lower than yesterday. As for temperatures, still
looking at seasonably cool temperatures across most of the region
again this afternoon - or similar to what what see on Sunday. For
tonight: Breezy to gusty offshore flow will persist overnight
with a shallow marine layer if one forms at all. Expect mild and
dry conditions most area, especially in the hills.

Given the ongoing wildfire in the North Bay smoke/haze was added
to the forecast for portions of the North and East Bay. For smoke
impacts and spare the air information check out information being
provided by the Bay Area Air Quality Management District (BAAQMD).

&&

.LONG TERM...
Issued at 300 AM PDT Mon Jun 17 2024
(Tuesday through Sunday)

Tuesday through Thursday: The upper level low exits the Great
Basin and moves further east into the Plains. For the West Coast
general troughing at 500 mb remains. For the most part that
translates to minor day to day changes with sensible weather.
Onshore flow does return, which helped to reestablish
night/morning marine layer clouds.

Friday into next weekend:The broad trough will fade and ultimately
be replaced by upper level ridging. As a result, a notable warming
and drying trend will develop, especially over the interior. Long
range forecast continues to advertise interior temperatures in
the 90s to lower 100s with elevated HeatRisk values. Stay tuned...

&&

.AVIATION...
(18Z TAFS)
Issued at 1058 AM PDT Mon Jun 17 2024

Currently VFR at all terminals. VFR through the TAF period for all
terminals except MRY. Thanks to wildfires in the area, high
pressure trapping the smoke, and northerly/northwesterly winds, smoke
will likely be seen across the area, particularly at the
terminals of APC, LVK, and STS, although no significant visibility
reductions are to be expected. With the exception of STS, winds
will become more westerly/onshore through the TAF period.

Vicinity of SFO...Currently VFR with northerly flow. VFR through the
TAF period. Winds will transition to become westerly this afternoon
with gusts up to 30 knots to be expected. Westerly winds diminish
overnight before becoming gusty again tomorrow afternoon.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Currently VFR with northwesterly flow at
both terminals. Winds will be gusty out of the west/northwest
through this evening before diminishing overnight. Moderate
confidence on MRY getting an IFR ceiling with lower confidence on if
it`ll reach SNS.

&&

.MARINE...
(Today through Saturday)
Issued at 1058 AM PDT Mon Jun 17 2024

Widespread strong northerly/northwesterly breezes with near gale-
force gusts will persist through Wednesday. These
northerly/northwesterly breezes will diminish overall beginning
Thursday with strong breezes remaining exclusive to the outer
waters. Significant wave heights will build to 10-12 feet today,
abate through Friday, and build back up to 10-12 feet towards the
end of the period.

&&

.FIRE WEATHER...
Issued at 245 AM PDT Mon Jun 17 2024

...Red Flag Warning remains in effect interior North Bay Mts
Monday...
...Elevated Fire Weather Conditions Through Monday night...

*Breezy to gusty northerly winds, especially higher terrain
*Lowering relative humidity values day and night

Point Wildfire (near Lake Sonoma): Latest heat trends on GOES
satellite and webcams show less heat, but that doesn`t mean the
fire is "out" or contained. For fire specific updates follow
CalFire for the latest. Weather wise, winds near the fire remain
NW with gusts in the 10-20 mph range. Despite the breezy
conditions, RH values have crept upward to moderate, which is
good. Transport flow continues to show smoke impacts SE of Lake
Sonoma stretching into the East Bay. This is also being reflected
at the surface with AQ sensors showing poor AQ. For more AQ info
check BAAQMD.

Overall fire weather concerns: No change with ongoing Red Flag
for interior North Bay for later today. The northerly shift in
winds are still on track with gusts in the 25-40 mph. Winds will
be strongest over the higher terrain of the North and East Bay.
While winds increase RH values will begin to plummet. Hi-res
guidance continues to advertise RH values dropping into the upper
single digits to lower teens this afternoon. The greatest impact
will be over the North Bay Interior Mts - hence the Red Flag.
Elsewhere, conditions will be marginal for Red Flag, but still
elevated nonetheless. Winds remain breezy offshore for Monday
night into Tuesday keeping elevated fire weather concerns in play.
Better relief arrive Tuesday into Wednesday with increased
onshore flow.

Longer range forecast will need some watching as hot and dry
conditions return to the district.

MM

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Red Flag Warning until 8 PM PDT this evening for CAZ504.

PZ...Small Craft Advisory until 9 PM PDT this evening for Mry Bay-Pt
     Arena to Pt Reyes 10-60 NM-SF Bay N of Bay Bridge.

     Small Craft Advisory from 3 PM to 9 PM PDT Tuesday for SF Bay N
     of Bay Bridge.

     Small Craft Advisory from 9 AM Tuesday to 3 AM PDT Wednesday for
     Mry Bay.

     Small Craft Advisory until 3 AM PDT Wednesday for Pigeon Pt to
     Pt Pinos 0-10 nm-Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena to
     Pt Reyes 0-10 nm-Pt Reyes to Pigeon Pt 0-10 nm.

     Gale Warning until 9 PM PDT this evening for Pt Pinos to Pt
     Piedras Blancas 0-10 nm.

     Gale Warning from 3 PM Tuesday to 3 AM PDT Wednesday for Pt
     Pinos to Pt Piedras Blancas 0-10 nm.

     Gale Warning from 9 PM this evening to 3 AM PDT Tuesday for Pt
     Arena to Pt Reyes 10-60 NM.

&&

$$

SHORT TERM...MM
LONG TERM....MM
AVIATION...Sarment
MARINE...Sarment

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