819
FXUS66 KMTR 251058
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
358 AM PDT Tue Jun 25 2024

...New AVIATION, MARINE...

.SYNOPSIS...
Issued at 315 AM PDT Tue Jun 25 2024

Elevated thunderstorms, with isolated to scattered coverage may
produce lightning strikes capable of igniting grass fires today
into the early evening hours.

&&

.SHORT TERM...
(Today and tonight)
Issued at 315 AM PDT Tue Jun 25 2024

Lift associated with an upper level low approaching the Pacific
Northwest over the next couple of days, is producing scattered
showers over the open water to our west. Lightning even farther west
and closer to the base of the trough can currently be seen tracking
northeast overnight. The persistent ridging over the desert
southwest will deflect the strongest energy associated with the
trough to our north over the next twenty four hours. Scattered
showers that develop this afternoon in an area of upper level
diffluent flow (mainly across Monterey Bay and points north) will be
capable of producing primarily elevated thunderstorms with limited
coverage. There is some concern for any elevated storms producing
lightning strikes across the northern half of our area being capable
of igniting a grassfire. However, instability is weak with little
to no CAPE evident. Later tonight into early Wednesday, upper
level flow across our latitude becomes more zonal as the upper
level low moves onshore into Washington state. Normal to slightly
above normal max temperatures inland today will cool a few degrees
tomorrow.

&&

.LONG TERM...
(Wednesday through Monday)
Issued at 315 AM PDT Tue Jun 25 2024

The southern extent of an upper level trough axis will shift east
across our area Thursday morning, as upper level flow shifts from
zonal to northwest and shortwave ridging over the Pacific Northwest
takes shape in the wake of the trough. The more amplified portion of
the upper ridge will remain north of our area and another upper
trough moves onshore over the weekend. Temperatures will cool nicely
from today`s peak, for the end of the week into the weekend as
cooler temperatures aloft spread over our region. A warmup looks
likely for the beginning of next week as broad troughing is
established across western CONUS.

&&

.AVIATION...
(12Z TAFS)
Issued at 355 AM PDT Tue Jun 25 2024

The low chance-high impact threat remains for high-based convection
through this evening. The latest lightning strikes were seen 300
miles off the coast of Point Piedras Blancas. Currently VFR at all
terminals. VFR through the TAF period for APC, LVK, SJC, and STS.
Overnight the Bay Area terminals of OAK and SFO will deteriorate
to low-end MVFR while the Monterey Bay terminals of MRY and SNS
will deteriorate to IFR. Winds will remain onshore through the TAF
period.

Vicinity of SFO...Currently VFR with westerly flow. Winds will
prevail out of the west through the TAF period. A low-end MVFR
ceiling will return to the terminal in the early morning hours of
Wednesday, scattering out towards the end of the TAF period.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Currently VFR and calm at both terminals.
Winds will prevail out of the west/northwest through the TAF period.
Low confidence on if LIFR stratus will return to the terminals this
morning, but moderate confidence in IFR stratus returning to both
terminals overnight.

&&

.MARINE...
(Today through Sunday)
Issued at 355 AM PDT Tue Jun 25 2024

  Fair weather and moderate to fresh northwesterly breezes will
prevail today. By Wednesday, surface high pressure over the
Eastern Pacific Ocean builds, tightening the pressure gradient,
resulting in strong northwesterly breezes through the end of the
period. Significant wave heights will continue to abate below 10
feet through the period.

&&

.FIRE WEATHER...
Issued at 315 AM PDT Tue Jun 25 2024

There is a slight chance of thunderstorms this afternoon, with
limited coverage. Given the elevated nature of any storms that
may develop, any rainfall amounts, if any, will be light with
some VIRGA possible and subsequent gusty winds. Any strikes that
do occur may cause a fire start in the fine fuels.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory from 3 PM to 9 PM PDT Wednesday for Mry Bay-
     Pt Arena to Pt Reyes 10-60 NM-Pt Reyes to Pigeon Pt 0-10 nm.

     Small Craft Advisory from 9 AM to 9 PM PDT Wednesday 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 Pinos to Pt Piedras Blancas 0-
     10 nm.

     Small Craft Advisory until 9 AM PDT this morning for Pt Arena to
     Pt Reyes 10-60 NM.

&&

$$

SHORT TERM...JM
LONG TERM....JM
AVIATION...Sarment
MARINE...Sarment

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