526
FXUS66 KMTR 191746
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
1046 AM PDT Thu Jun 19 2025
...New AVIATION...
.SYNOPSIS...
Issued at 305 AM PDT Thu Jun 19 2025
Cooling trend starts today and will continue into the weekend.
Elevated fire weather concerns across much of our interior today,
especially elevated grassy areas where gusty winds will combine with
dry conditions and increasing fuels. King tide coastal flooding
possible Sunday into the beginning of next week.
&&
.UPDATE...
Issued at 854 AM PDT Thu Jun 19 2025
Lingering stratus continues to slowly mix out across the western
San Mateo Peninsula and the Monterey Bay region. Stations within
the interior mountains are reporting low relative humidity values
this morning with single digit percent RH values reported at the
highest peaks in the interior ranges. Elevated fire weather threat
continues through the day as wind gusts pick up across the
interior. No changes to the forecast.
DialH
&&
.SHORT TERM...
(Today and tonight)
Issued at 305 AM PDT Thu Jun 19 2025
The first of several shortwave troughs will begin to transect our
area later this afternoon into tonight. Temperatures will be right
around normal today with breezy winds this morning out ahead of the
first weak cold front that pushes through our area this afternoon.
Winds increase behind the surface becoming gusty later today and
tonight front especially at higher elevations inland and near the
surface along the coast. Wind gusts up to 50 MPH are possible above
2000ft across the East Bay hills during the overnight into early
Friday morning. A wind advisory is not expected attm.
&&
.LONG TERM...
(Friday through Wednesday)
Issued at 305 AM PDT Thu Jun 19 2025
Robust onshore flow Friday will result in the marine layer expanding
and penetrating farther inland as an upper low pushes inland across
the Pacific Northwest and a tightening pressure gradient continues
the gusty winds along the coast and elevated interior locations
through late Saturday into early Sunday. Fire weather concerns
abate for Friday into the weekend despite the gusty winds with
improved RH recovery. Still watching the upper level pattern for
Sunday into the beginning of next week, for the potential of a
stalled upper low/trough possibly leading to weak offshore flow
and increased fire weather concerns.
&&
.AVIATION...
(18Z TAFS)
Issued at 1035 AM PDT Thu Jun 19 2025
A few morning clouds, but they have all but faded for the most
part. Half Moon Bay on the other hand is doing Half Moon Bay
things...it`s still cloudy. The bigger story for today will be the
tightening onshore gradient from SFO-SAC leading to gusty onshore
flow and a mixed lower atmosphere. AWW remains for SFO with gusts
GT 35kts. Tonight is a lower confidence forecast as onshore flow
eases ever so slightly allowed for a mix marine layer with a few
cigs. Will bring in some cigs late, but expect another early
clearing tomorrow.
Vicinity of SFO...VFR through late tonight. Winds gradually ramp
up through 19-20Z before peaking after 22Z. 35kt seems like a safe
bet, but 40kt would be the upper end at 20% chc. Will bring in a
few cigs late tonight into Friday am. About 40-50% chc on cigs
below 5k feet. Will likely need another AWW for Friday.
SFO Bridge Approach...Less likely for cigs tonight.
Monterey Bay Terminals...VFR through this afternoon. Cigs return
this evening as sun begins to set. MVFR cigs tonight into Friday
AM.
&&
.MARINE...
(Today through Tuesday)
Issued at 854 AM PDT Thu Jun 19 2025
A cold front pushed through the region overnight. Behind the front
widespread gale force winds have developed over the coastal
waters. Winds ease from gale force to near gale force late Friday
into Saturday persisting into early next week. Winds will be
strongest across the outer waters and for the inner coastal waters
north of Point Reyes and south of Point Sur, where coastal jets
are expected to develop. Significant wave heights build to 10 to
12 feet across the coastal waters Thursday into the weekend before
abating early next week.
&&
.FIRE WEATHER...
Issued at 305 AM PDT Thu Jun 19 2025
Elevated fire weather concerns today with strong winds gusting at
25 to 40 mph and daytime relative humidities of 15 to 25%
developing across the interior, with the biggest threat coming in
the interior mountains of the North Bay, the interior East Bay,
the eastern Santa Clara Hills, and the Gabilan Range in interior
Monterey and San Benito Counties. Fuels have been curing across
the interior, especially across the finer fuels of grass and
brush, and there`s already been several notable grass fires across
the interior portions of the region. However, the fact that winds
will remain onshore and temperatures will cool will keep fire
weather conditions below critical levels into the weekend.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 3 AM PDT Friday for Mry Bay-SF Bay N
of Bay Bridge.
Gale Warning until 9 AM PDT Friday for Pt Arena to Pt Reyes 0-10
nm-Pt Arena to Pt Reyes 10-60 NM-Pt Reyes to Pigeon Pt 0-10
nm.
Small Craft Advisory until 9 AM PDT Friday for Pigeon Pt to Pt
Pinos 0-10 nm.
Gale Warning until 3 AM PDT Friday for Pigeon Pt to Pt Pinos 10-
60 NM-Pt Pinos to Pt Piedras Blancas 0-10 nm.
&&
$$
SHORT TERM...JM
LONG TERM....JM
AVIATION...MM
MARINE...MM
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