638
FXUS66 KMTR 201729
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
1029 AM PDT Fri Jun 20 2025

...New AVIATION, MARINE...

.SYNOPSIS...
Issued at 323 AM PDT Fri Jun 20 2025

Cooler than normal temperatures today will continue into the
weekend. Elevated fire weather concerns today and tomorrow,
especially interior 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.

&&

.SHORT TERM...
(Today and tonight)
Issued at 323 AM PDT Fri Jun 20 2025

A deepening upper level low has begun shifting south out of the Gulf
of Alaska into the Pacific Northwest early this morning. A
tightening height field gradient over NorCal and the Central Coast
will result in gusty onshore flow persisting today and tonight.
Isolated gusts in the 40s and 50s occurred Thursday afternoon and
evening and should see similar speeds for today. Temperatures will
continue to be cooler, 5-10 degrees below normal for this time of
year.

&&

.LONG TERM...
(Saturday through Thursday)
Issued at 323 AM PDT Fri Jun 20 2025

Saturday morning temperatures may come with a little chill in the
air with H85 temps dropping into single digits, and potentially
approaching a daily record minimum (~5C) according to the sounding
climatology kept by the Storm Prediction Center. Despite the cooler
temperatures, gusty winds and continued dry conditions along the
elevated interior eastern hillsides will lead to elevated fire
weather concerns, highlighted in the day two SPC Fire Weather
Outlook. By early Sunday morning the strongest of several trough
axis` exits east with wind speeds easing somewhat, and gradually
improving RH recoveries helping to mitigate widespread fire weather
concerns. Plenty of uncertainty remains in the synoptic pattern for
the beginning of next week and beyond until models get a handle on
the evolution of the large dome of high pressure across the eastern
half of the country.

&&

.AVIATION...
(18Z TAFS)
Issued at 1028 AM PDT Fri Jun 20 2025

Patches of stratus near HAF and Monterey Bay will mix out through
the afternoon. Strong and gusty northwest winds will continue
through the TAF period, especially along the immediate coast and
through the San Bruno Gap. Some LLWS is possible across the North
Bay tonight through Saturday morning as surface winds decouple from
flow aloft. Low confidence of stratus development along the
immediate coast late tonight through Saturday morning.

Vicinity of SFO... VFR through the TAF period. Strong northwesterly
gusts of 40 to 45 kt are expected through late tonight, with gusts
around 20 to 30 knots continuing through the TAF period. Monitoring
possibility of gusts exceeding 35 knots on Saturday afternoon;
confidence is too low to include in the TAF but some high resolution
model guidance is pointing to development of strong gusts.

SFO Bridge Approach... Similar to SFO.

Monterey Bay Terminals... MVFR stratus mixing out to VFR within the
next couple of hours. Breezy northwest winds gusting to 25 knots
will develop this afternoon and into the evening. A low confidence
for MVFR-IFR ceilings at MRY tonight, driven mainly by high
resolution models expecting development on the northern edge of the
Santa Lucias. Otherwise, VFR at the terminals through the end of the
TAF period.

&&

.MARINE...
(Today through Wednesday)
Issued at 1028 AM PDT Fri Jun 20 2025

Widespread hazardous marine conditions continue through the
weekend with strong northwesterly breezes, gale force gusts, and
rough to very rough seas. Fresh to strong northwesterly breezes
and moderate to rough seas are expected through the middle of
next week.

&&

.FIRE WEATHER...
Issued at 323 AM PDT Fri Jun 20 2025

Elevated fire weather conditions continue today across the
interior becoming more widespread on Saturday, with RH values
around 30% expected across the interior of the East Bay south
through the Gabilan Range, along with the Santa Lucia mountains
this afternoon. Gusty winds above the marine layer and elevated
interior locations will once again be around 25 to 40 mph with
less coverage today than Thursday. Brief periods of critical fire
weather conditions are possible with daytime relative humidities
of 15 to 25% in the interior. However, continuing marine layer
influence, especially during the night, and the fact that winds
remain onshore, mean that widespread critical fire conditions do
not develop across the district. Gusty winds begin to subside
somewhat on Saturday, but the upper level pattern will lead to
more northerly winds developing across the region. As with
Thursday`s fire weather threat, widespread critical fire weather
conditions are not expected within the district, although the fire
weather threat will increase once again for areas closer to the
Central Valley. The fire weather threat will continue to diminish
Sunday into the early part of next week with the gusty winds
further relaxing, although humidity values in the interior will be
slow to rise.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 9 PM PDT Saturday for Mry Bay-SF Bay
     N of Bay Bridge.

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

     Gale Warning until 3 PM PDT this afternoon for Pigeon Pt to Pt
     Pinos 10-60 NM.

&&

$$

SHORT TERM...JM
LONG TERM....JM
AVIATION...DialH
MARINE...DialH

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