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

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FXUS66 KMTR 220540
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco Bay Area
1040 PM PDT Sat May 21 2022

.SYNOPSIS...Look for a gradual warming trend this weekend with
more robust warming across the interior early next week. A
cooldown is then likely late next week and into the upcoming
holiday weekend.

&&

.DISCUSSION...as of 08:55 PM PDT Saturday...

Patchy stratus is developing around Monterey Bay this evening,
with model indications that the marine layer should stick around
overnight in this area. Only forecast change was to add patchy fog
mention around Monterey Bay where some of the high resolution
models suggest lower visibilities may develop later tonight
towards morning. The forecast is in good shape with no other
planned changes.

&&

.PREV DISCUSSION...as of 01:33 PM PDT Saturday...Pleasant weather over
the weekend, but a taste of summer arrives early next week with
increased fire weather concerns.

Today and Sunday: Upper level high pressure lurking offshore
continues to inch closer to the coast. As 500mb heights increase
aloft skies will remain mostly sunny during the day with a shallow
marine layer developing at night. The shallow marine layer will
result in patchy coastal clouds during the morning hours.
Temperatures today are running a few degrees warmer than Friday
and will peak in the 60s/70s coast/bays and 70s/80s interior.
Temperatures will likely be a few degrees warmer on Sunday,
especially across the interior.

Monday through Wednesday: The upper level high pressure moves over
the region resulting in a robust warm up. The warm up will
initially be across the interior on Monday and then more
widespread Tuesday with slight coastal cooling WEdnesday. Model
trends as of late have been trending warming, especially Tuesday.
ECMWF Extreme Forecast Index continues to highlight much of the
region as being above normal for temperatures day and night
Monday through Wednesday. Additionally, hi-res model guidance is
also showing solid northerly to offshore flow develop Monday night
through Tuesday. This downslope flow will only enhance the heat
potential across the interior. Therefore, temperatures were
nudged upward on Tuesday with the North and East Bay 95-100
degrees in the warmest locations. Max temps were also increased
along the coast due to the warmer northerly/offshore flow. Despite
the bump in temps still not yet record territory, but definitely
above seasonal averages. Temperatures do dip slightly on Wednesday
as the ridge of high pressure weakens and onshore flow begins to
redevelop.

Breezy offshore flow will help to usher in much drier air.
Forecast humidity readings Tuesday afternoon from the WRF are in
the upper single digits to lower teens. Hot, dry, and breezy
conditions will most certainly increase fire concerns Tuesday.
Latest ERC and fuels charts are turning corner toward summer and
the spring rains are being erased. Will have to closely monitor
this the next few days and coordinated with fire partners and
neighboring forecast offices.

Thursday into the Holiday weekend: Widespread cooling is expected
by Thursday as an upper level trough moves through the region.
Interestingly the deterministic ECMWF brings some showers to the
North Bay next Friday, but ensemble guidance not so much. Forecast
is dry for now. The trough will at a minimum bring cooler
temperatures.

&&

.AVIATION...as of 10:40 PM PDT Saturday...For the 06Z TAFs. VFR
with some patchy low clouds entering the Monterey Peninsula.
For later tonight, except shallow, patchy stratus and fog
developing along the coast and nearby bays lasting into Sunday
morning. Morning stratus and fog lifting to VFR by late Sunday
morning and early afternoon. Breezy to gusty afternoon and evening
west winds expected again Sunday.

Vicinity of KSFO...VFR. Northwest winds have diminished and are
around 10 to 15 kts, which will persist through the night before
increasing again Sunday afternoon. W/NW winds will be around 25 to
30 kts again through Sunday evening.

KSFO Bridge Approach...Similar to KSFO.

Monterey Bay...IFR with low clouds entering MRY terminal from the
southern waters. Patchy stratus and fog (IFR-LIFR) will continue
through the night into Sunday morning. Conditions improving to VFR
by late morning and early afternoon. Calmer winds tonight out of
the W/SW in MRY. Slightly breezier tonight at KSNS with winds out
of the NW. Onshore winds 5 to 15 kts expected Sunday afternoon and
evening.

&&

.MARINE...as of 08:55 PM PDT Saturday...Strong northwest winds
with near gale force gusts in the northern outer waters will
persist through the weekend, with widespread  steep, hazardous
seas. Winds near the immediate coastline are  forecast to be
generally lighter, but still strong near coastal jets. Prevailing
wave heights over 10 feet at periods of 9 to 11  seconds through
the weekend will keep hazardous seas, particularly for smaller
vessels. Winds are expected to restrengthen early  next week.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .Tngt...GLW...Pt Arena to Pigeon Pt 10-60 nm
             SCA...Pt Arena to Pt Reyes 0-10 nm
             SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm

&&

$$

PUBLIC FORECAST: MM/SPM
AVIATION: McCorkle
MARINE: Canepa

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