Millbrae, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

514
FXUS66 KMTR 201032
AFDMTR

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

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

.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...
(06Z TAFS)
Issued at 935 PM PDT Thu Jun 19 2025

Cold air advection, a deepening marine layer, upsloping winds and
radiative cooling favor coastal stratus /MVFR/ redevelopment with
local inland intrusions tonight and Friday morning. Drier air
arrives from the north and northwest Friday with clearing /VFR/
from north to south. Areas of strong and gusty west to northwest
winds continue through the evening, with some relaxation in winds
overnight then strengthening west to northwest winds redeveloping
Friday during the day. Based on recent HREF output, expect mainly
VFR except areas MVFR ceilings along the immediate coastline
Friday night and early Saturday morning.

Vicinity of SFO...Gusty onshore winds gradually easing overnight
then west wind strengthening again Friday with gusts to 35 knots.
BKN-OVC ceiling prevailing tonight to 15z-16z Friday. Radiative
cooling tonight will help restore a stratus feed to SFO for the
overnight.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Onshore winds, cold air advection,
nocturnal cooling and a deepening marine layer support MVFR
stratus ceilings tonight and Friday morning. Stratus mixing
out to VFR by late Friday morning and SCT-BKN low clouds
return Friday evening and night. Onshore winds 10 to 15 knots
with occasional gusts to 20 knots.

&&

.MARINE...
(Today through Wednesday)
Issued at 323 AM PDT Fri Jun 20 2025

Widespread hazardous marine conditions will persist 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 Monday and Tuesday.

&&
today`s
.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...Canepa
MARINE...Sarment

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