727
FXUS66 KMTR 081936
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
1236 PM PDT Tue Jul 8 2025

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

.KEY MESSAGES...
Updated at 1200 PM PDT Tue Jul 8 2025

 - A warming trend will bring minor to moderate HeatRisk for
   inland and higher elevations Thursday - Friday.

 - Localized elevated fire weather conditions starting Wednesday
   across the higher elevations.

&&

.SHORT TERM...
Issued at 1200 PM PDT Tue Jul 8 2025
(This evening through Wednesday)

The marine layer is currently between 2,200 and 2,700 feet as weak low
pressure remains offshore. This system will gradually move inland
over the next 36 hours while weakening. Meanwhile, its previous
position offshore will be replaced by ridging from subtropical
high pressure in the Eastern Pacific. This pattern change will
cause the marine layer to compress while onshore NW winds
increase. All this means that temperatures will begin to increase
starting Wednesday. Highs are forecast to be around 5-10 degrees
warmer than today for inland areas. While becoming more shallow,
the marine layer will continue to keep coastal areas in the 60s.

&&

.LONG TERM...
Issued at 1200 PM PDT Tue Jul 8 2025
(Wednesday night through next Monday)

The warming trend will continue into Thursday as the synoptic high
pressure becomes more established offshore. For inland areas, this
will cause another 5-10 degree jump in temperatures from
Wednesday. Some interior and high elevation areas will experience
moderate HeatRisk from Thursday - Friday with afternoon
temperatures in the 90s. A very weak mid-level disturbance will
bring some relief over the weekend, but broadly speaking the
pattern looks fairly stable through at least early next week.
There will be a very broad area of high pressure across the Northeast
Pacific, with an embedded mesoscale high sitting over the Channel
Islands. While ensembles are confident that the persistent high
pressure will increase the 850 mb temperature to around 24C (90th
percentile) by Saturday, this pattern supports steady onshore
wind. With ocean temperatures cooler than normal (54F), the marine
layer should continue to keep coastal areas seasonably cool, even
while the Central Valley flirts with triple digit heat throughout
the long term forecast. There is some elevated fire weather
concerns above and inland of the marine layer`s influence. The RH
will drop below 30% at times, and afternoon wind gusts will reach up
to 30 mph. Fortunately with onshore winds, these conditions will
be diurnally driven with lighter winds and good humidity recovery
in the foothills expected each night.

&&

.AVIATION...
(18Z TAFS)
Issued at 946 AM PDT Tue Jul 8 2025

Currently a mixed bag of VFR-MVFR at the terminals with an early
improvement to VFR on tap. The marine layer is currently being
observed at 2,600 feet on the Fort Ord profiler. Just what happens
to it over the next 24-30 hours will be heavily dependent on the
upper-level pattern as broad upper-level ridging builds in from the
Desert Southwest while an upper-level trough swings through Northern
California, likely leading in a deepening marine layer from south to
north. For now greatest confidence is in widespread low-end MVFR
with the possibility for IFR ceilings, particularly at the coastal
terminals of HAF, MRY, and SNS.

Vicinity of SFO...Currently VFR with northeasterly flow. Westerly
flow will begin to prevail this afternoon once the sea breeze kicks
in. Moderate to high confidence on the return of sub-VFR ceilings to
the terminal tonight with ceilings likely being on the cusp of low-
end MVFR to IFR.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Currently MVFR and calm at both terminals
with high confidence in VFR being achieved shortly based on
satellite trends. Moderate to high confidence on the return of sub-
VFR ceilings to the terminals tonight. Uncertainty resides in the
ceiling height due to the fact that the terminals will likely begin
to be affected by the upper-level ridge which would subsequently
result in subsidence aloft, a compressed marine layer, and thus
relatively lower ceilings and visibilities. The key will be on if
this can happen tomorrow morning instead of tomorrow afternoon, if
so it is reasonable to believe that the terminals may be in the LIFR-
IFR category instead of low-end MVFR.

&&

.MARINE...
(Today through Sunday)
Issued at 926 AM PDT Tue Jul 8 2025

A gentle southerly breeze and moderate seas will prevail today.
Winds will strengthen and veer to become moderate and northerly by
Wednesday with further strengthening to become fresh to strong on
Thursday and into the weekend. Significant wave heights will be
rough to very rough Thursday through Saturday for the outer
waters.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory from 3 PM Wednesday to 3 AM PDT Thursday
     for Pigeon Pt to Pt Pinos 10-60 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.

&&

$$

SHORT TERM...Flynn
LONG TERM....Flynn
AVIATION...Sarment
MARINE...Sarment

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