234
FXUS66 KMTR 171000
AFDMTR

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

...New SYNOPSIS, SHORT TERM, LONG TERM, MARINE, FIRE WEATHER...

.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.

&&

.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...
(06Z TAFS)
Issued at 1055 PM PDT Sun Jun 16 2024

VFR through the TAF period. Strong and gusty winds linger along the
immediate coast and at SFO into the mid morning, with more inland
areas seeing light to moderate. Winds aloft are still strong and
will stay so into the early morning, particularly over the North Bay
causing concerns for LLWS at STS. Winds aloft and at the surface
weaken in the mid morning. Expect winds to increase again into the
afternoon, with strong winds over the ocean and at SFO. Elevated
winds last into the late night before reducing. A fire in the North
Bay will cause some reduction to visibility around STS and
potentially APC.

Vicinity of SFO...VFR through the TAF period. Winds stay gusty
through the mid morning before reducing and staying more moderate.
Another round of gusty winds starts building in the afternoon with
peak gusts  expected to be around 28 kts. These stronger gusts last
into the late night, before winds reduce and become moderate again.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR through the TAF period. Light to
moderate winds last into  Monday afternoon before more breezy
westerly winds arrive. Winds at the terminals reduce into the
evening, but looks to stay moderate.

&&

.MARINE...
(Today through Saturday)
Issued at 158 AM PDT Mon Jun 17 2024

Widespread gale force gusts continue before diminishing gradually
into Sunday night. By early Monday, gale force gusts will have
weakened to strong to near gale force with widespread conditions
dangerous to small crafts persisting through mid-week. Significant
wave heights will peak between 12 to 14 feet Sunday into Monday
before gradually diminishing to 8 to 11 feet by mid- week.
Hazardous conditions will persist through the late work week with
strong gusts expected to continue over the majority of the coastal
waters.

&&

.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 from 11 AM this morning to 8 PM PDT this
     evening for CAZ504.

PZ...Small Craft Advisory until 3 AM PDT early this morning for Mry
     Bay-SF Bay N of Bay Bridge.

     Gale Warning until 3 AM PDT early this morning 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 Arena to Pt Reyes 10-60 NM-Pt Pinos to
     Pt Piedras Blancas 0-10 nm-Pt Reyes to Pigeon Pt 0-10 nm.

&&

$$

SHORT TERM...MM
LONG TERM....MM
AVIATION...SO
MARINE...SO

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