Walnut Creek, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

251
FXUS66 KMTR 111000
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
300 AM PDT Fri Apr 11 2025

...New SYNOPSIS, SHORT TERM, LONG TERM...

.SYNOPSIS...
Issued at 258 AM PDT Fri Apr 11 2025

Gradual cooling today and tomorrow before more widespread minor
HeatRisk returns on Sunday into the beginning of next week.

&&

.SHORT TERM...
(Today and tonight)
Issued at 258 AM PDT Fri Apr 11 2025

High clouds streaming northeast across our area overnight on the
backside of the flattening ridge to our east, indicate some cloud
top cooling associated with weak lift from an elongated trough
developing to our west. 00z KOAK sounding showed dry air from the
surface up to 15kft. Decided against adding mentionable PoPs,
thinking the dry air is too much to overcome attm. KMRY surface
observation dropped a couple of degrees as soon as there was a break
in the high cloud cover around 2AM PDT. Overall adjusted this
mornings low temperatures up slightly to account for the lack of
radiational cooling with the mid/high level clouds that will be over
our area by sunrise. This complicates the extent of fog/drizzle that
was expected this morning. Can`t rule out some marine layer drizzle
along the coast, but confidence is low with the high clouds moving
in. Temperatures this afternoon in our coastal areas will be right
around normal, in the low to mid 60s. Inland temperatures will be 5-
10 degrees warmer than normal, with the warmest spots in the
southern valleys of Monterey County, that will climb into the mid
80s.

HiRes short term guidance does suggest that the marine layer will be
more robust tonight into Saturday morning with the potential for
low stratus with fog/drizzle, however more interference from the
presence of mid/high level cloud cover is possible once again.

&&

.LONG TERM...
(Saturday through Thursday)
Issued at 258 AM PDT Fri Apr 11 2025

A cool and dry airmass is still on schedule to arrive with the
secondary trough pushing a weak backdoor cold front south through
our area Saturday night into Sunday. Weekend overnight low
temperatures will be on the cool side before warming up nicely in
the afternoon under increasing sun angle. As the backdoor cold front
pushes south through our area during the day Sunday we`ll see a
return of minor HeatRisk inland as temperatures climb above normal
once again. Weak offshore flow will hold the marine layer at bay as
drier air scours south for Sunday and Monday. HiRes guidance does
indicate that the marine layer may hold on strong enough around
Monterey Bay late Saturday into Sunday morning, however confidence
is low attm given the weak forcing associated with an elongated
trough splitting from the polar jet over the weekend, as a cut off
low develops over the waters off of SoCal. Otherwise expect pleasant
temperatures and plenty of sunshine inland through the extended
forecast, and more seasonal temperatures with some pockets of night
time stratus possible along the coast.

&&

.AVIATION...
(06Z TAFS)
Issued at 940 PM PDT Thu Apr 10 2025

LIFR and IFR CIGs are building along the coast, affecting HAF, and
will slowly move inland into Friday morning. These CIGs will affect
the SF and Monterey Bays, and the North Bay terminals into the
morning. In addition to CIGs, the North Bay terminals look to see
moments of fog into the mid morning. Cloud cover and fog erode into
the late morning and into Friday afternoon as more moderate winds
arrive. Winds reduce into Friday evening and into that night as CIGs
build into the coast once again.

Vicinity of SFO...VFR lasts into early Friday. Expect winds to
reduce and become more moderate through much of the night. IFR CIGS
move into the SF Bay into the late night will have moments of
filling over SFO into early Friday morning. These CIGs dissipate in
the mid morning ahead of more breezy west winds building that
afternoon.

SFO Bridge Approach...IFR clouds arrive slightly later than SFO into
Thursday morning.

Monterey Bay Terminals...Winds stay light through the morning late
morning. IFR/LIFR CIGs arrive early Friday for MRY and last into the
late morning. SNS looks the have inconsistent CIGs during that
time. Moderate west winds build for Friday afternoon but weaken
again into the evening as IFR CIGs fill over the terminals.

&&

.MARINE...
(Tonight through next Wednesday)
Issued at 940 PM PDT Thu Apr 10 2025

Areas south of Point Sur continue to see breezy winds causing
hazardous conditions for small craft. Northwest winds will
strengthen across the waters by Friday afternoon with near gale
force gusts, especially across the norther outer waters. A larger
swell will build over the weekend and early next week. Winds
diminish and seas subside into the middle of the upcoming week.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory from 3 PM this afternoon to 9 PM PDT this
     evening for Mry Bay.

     Small Craft Advisory from 9 AM this morning to 3 AM PDT Saturday
     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.

     Small Craft Advisory from 9 AM this morning to 9 PM PDT this
     evening for Pt Reyes to Pigeon Pt 0-10 nm.

     Gale Watch from this evening through late tonight for Pt Reyes
     to Pigeon Pt 0-10 nm.

     Small Craft Advisory until 3 AM PDT Saturday for Pt Pinos to Pt
     Piedras Blancas 0-10 nm.

     Small Craft Advisory from 9 AM this morning to 3 PM PDT this
     afternoon for Pt Arena to Pt Reyes 10-60 NM.

     Gale Watch from this afternoon through late tonight for Pt Arena
     to Pt Reyes 10-60 NM.

&&

$$

SHORT TERM...JM
LONG TERM....JM
AVIATION...Behringer
MARINE...Murdock

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