Area Forecast Discussion
Issued by NWS San Francisco Bay Area, CA

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000
FXUS66 KMTR 191004
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
304 AM PDT Tue Mar 19 2024

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

.SYNOPSIS...
Issued at 301 AM PDT Tue Mar 19 2024

Despite the increase in coastal stratus, rain will stay out of the
forecast through Thursday. By Friday, a cold front will bring
periods of light to moderate rain and cooler temperatures through
the weekend.

&&

.SHORT TERM...
(Today and tonight)
Issued at 301 AM PDT Tue Mar 19 2024

The current low-cloud enhanced IR satellite image looks a lot like
early summer with a stratus-filled marine layer intruding into
coastal areas and neighboring valleys. The cloud base is a few
hundred feet lower than yesterday, and the Ft. Ord profiler is
measuring the marine layer depth at around 1,000 ft. This makes
patchy fog possible later this morning, and there is some
indication of mist beginning to form on regional traffic cameras.
The HRRR has a great handle on the current stratus coverage, and
suggests the low clouds will break by mid-day, allowing another
sunny and warm afternoon.

&&

.LONG TERM...
(Wednesday through Monday)
Issued at 301 AM PDT Tue Mar 19 2024

Wednesday and Thursday will be similar to Tuesday. Marine layer
stratus and patchy fog in the morning will give way to clear
afternoons and warmer than average temperatures. The pattern will
change on Friday as a cold front approaches from the Eastern
Pacific. Moderate southerly winds will shift to westerly in the
afternoon. Light to moderate rain is also expected on Friday,
although a few stronger showers are possible as the surface front
moves through. Unsettled weather will persist Saturday, although
precipitation will be more hit-or-miss showers compared to Friday.
Lingering light showers will likely persist into Sunday. In
addition to the rain and wind, the temperature will be noticeably
colder this weekend. Expect coastal areas to stay in the 50s,
while some inland valleys break into the low 60s. As an example of
this cool-down, Pinnacles National Park recorded a high
temperature of 79F Monday. The forecast high for Sunday is only
59F.

&&

.AVIATION...
(06Z TAFS)
Issued at 1104 PM PDT Mon Mar 18 2024

Currently VFR with Night Fog showing stratus starting to approach
coastal airport terminals. As mentioned in the 00Z discussion,
ceilings will be the main restrictor over visibility tonight with a
few coastal sites, HAF and OAR, reporting unlimited visibilities and
ceilings less than 1000 feet. Pushed back the arrival of stratus for
SFO, OAK, and SJC. Conditions are still breezy at SFO and OAK which
may limit fog development potential for the next few hours. Winds
will start to drop off between 07-09Z so pushed back stratus arrival
to 07Z. Moderate confidence that fog will develop at STS overnight
with the highest probabilities between 11-16Z. Moderate confidence
that stratus will move into APC overnight with slightly lower
confidence that fog conditions will develop.

Vicinity of SFO...Currently VFR with IFR conditions expected
overnight. Night fog shows stratus developing to the west of SFO but
not quite reaching the airport yet. Pushed back the arrival of
stratus at SFO to 07Z with guidance indicating 07-09Z as the
likeliest time for stratus to arrive. Breezy northwest winds will
gradually weaken and become light overnight. In terms of timing,
models already had light winds forecast at 00Z but observations show
breezier conditions are still ongoing. Current TAF has winds
weakening at 07Z but breezier conditions may linger until 09Z.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Currently VFR with conditions expected to
transition to IFR within the next hour. Night Fog shows stratus
beginning to move inland from the Monterey Bay with stratus stopping
just shy of MRY and SFO in the latest image. IFR to LIFR ceilings
are possible overnight with some potential for fog development in
the early morning. Moderate to high confidence that IFR stratus will
develop at MRY and SNS, low to moderate confidence that fog will
develop. Light, SW winds at MRY and light, NW winds at SNS are
expected overnight with moderate NW winds to return during the
day.

&&

.MARINE...
(Today through Sunday)
Issued at 301 AM PDT Tue Mar 19 2024

High pressure to continue through mid week with an incoming low
pressure system moving into the area on Thursday. Gentle NW winds
and dry conditions will linger through Wednesday before winds
strengthen and become more southerly late Wednesday into Thursday.
Rain chances will increase over the waters late Thursday with
elevated precipitation chances continuing into the weekend. A
moderate period northwesterly swell continues to diminish with a
new, longer period northwesterly swell train arriving Thursday.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory from 9 AM this morning to 9 AM PDT
     Wednesday for Pt Pinos to Pt Piedras Blancas 0-10 nm.

&&

$$

SHORT TERM...Flynn
LONG TERM....Flynn
AVIATION...Kennedy
MARINE...Kennedy

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