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

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FXUS66 KMTR 061225

Area Forecast Discussion
National Weather Service San Francisco CA
525 AM PDT Tue Jun 6 2023

...New AVIATION...

Issued at 408 AM PDT Tue Jun 6 2023

Potential for showers and the occasional thunderstorm continue
this morning, however, the better instability looks to be east and
south of our region. By Wednesday, conditions will be drier for
the rest of the work week, though below normal temperatures will
persist for afternoon highs.


(Today and tonight)
Issued at 408 AM PDT Tue Jun 6 2023

Water vapor imagery on satellite shows the upper low centered over
the SoCal coastline near Santa Barbara & Ventura counties. All
night, we`ve been watching showers and thunderstorm activity
moving across the Sierra as well as across SoCal, but shower
activity has been very minimal for our CWA.

As suggested by the hi-res models (NAM, HRRR, HREF) we have begun
to see some showers move across southern Monterey County in the
past couple of hours with those showers then pushing offshore over
the coastal waters (no lightning strikes though on the graveyard
shift). We don`t have as many rain gauges in that portion of the
county, but the Three Peaks CNRFC station on the southern side of
Fort Hunter Liggett has received 0.04" in the past 6 hours.
Otherwise, the only other readings we`ve got have been a hundredth
or two sporadically around the Bay Area in the past 6 hours.

Given that shower activity wasn`t very impressive yesterday
afternoon through now, have nudged lower for POPs and Potential
T-storms than the NBM for this morning`s forecast. Have reduced
shower chances to around 15% to 35% with a 20% chance of
thunderstorms. The hi-res models continue to suggest that we could
see another round of hit or miss showers this morning, mainly
between 5 am to 10 am. That`s when the NAM, ECMWF, and GFS are
showing increased RH (75-90%) in the 700-500 mb layer. Both the
HRRR and the HREF have indicated a somewhat N-S linear feature
that develops just along the Big Sur coastline around 8-9 am
before moving west over the ocean so it`ll be interesting to see
if that comes to fruition. Any additional rain amounts today will
likely be around a tenth of an inch or less based on WPC
guidance...with the caveat that any thunderstorm development would
likely produce locally higher amounts of rain.

Southerly wind regime persists today with breezy conditions
developing again this afternoon into evening with gusts ranging 15
to 25 mph.


(Wednesday through Monday)
Issued at 408 AM PDT Tue Jun 6 2023

No major changes in the long term forecast. The upper low will
linger over SoCal through midweek, then gradually push eastward
and weaken as a broader trough pattern develops offshore in the
Thursday/Friday timeframe. Thus, cooler than normal temperatures
will persist through the week with inland highs in the 60s and
70s while the cooler coastal areas remain in the 50s and 60s.

Ensembles and WPC Cluster analysis continue to indicate that
another upper low will form over Central CA & Socal this weekend
into early next week. This could introduce another round of rain,
however, current ensemble output suggests that rain amounts would
be spotty and light (less than 0.10"). Will continue to monitor
for details as we get closer to the weekend.


(12Z TAFS)
Issued at 525 AM PDT Tue Jun 6 2023

A mix of VFR/MVFR/IFR conditions over the region with mostly MVFR
and IFR cigs prevailing over the North Bay and Monterey Bay
terminals. As the morning continues to approach, expect any
lingering IFR cigs to improve to MVFR then eventually VFR by the
afternoon/evening for all terminals except KMRY. Westerly to
southwesterly winds are expected to transition from moderate to
breezy and/or gusty winds starting in the early afternoon. Gusty
winds can get up to 20 knots for some terminals. Showers are
expected to move out our area by the afternoon. Return of stratus is
expected tonight but models disagreement gives some uncertainty on
timing and height of cigs.

Vicinity of SFO...VFR with the possibility of some vicinity showers.
High confidence that VFR will prevail for most of the morning but
moderate confidence on timing of MVFR cigs for tonight. Winds are
breezy/gusty but had moderate confidence on wind speed as winds are
have been inconsistent between moderate to breezy this morning.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...A mix of MVFR and IFR conditions prevail.
Expect conditions to remain MVFR through the TAF period with moments
of IFR for KMRY, whereas KSNS may see VFR conditions this afternoon.
Winds are expected to become gusty this afternoon up to 17 knots.


(Today through Sunday)
Issued at 308 AM PDT Tue Jun 6 2023

Localized gusty winds continue Tuesday, with the strongest gusts
during afternoon and evening hours. This will create hazardous
conditions for small craft from the Golden Gate to Half Moon Bay
and from Santa Cruz Harbor to Point Sur. Potential for
thunderstorms continues Tuesday morning into afternoon over the
waters, especially in the southern waters. Gusty and erratic
winds, lightning, and small hail possible near storms. Winds
shift to the northwest on Friday and build through the weekend.


PZ...Small Craft Advisory until 9 PM PDT this evening for PZZ530-535-

     Small Craft Advisory from 9 AM this morning to 9 PM PDT this
     evening for PZZ545-560.




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