Technical NOAA Weather Discussion

FXUS66 KMTR 180441

Area Forecast Discussion
National Weather Service San Francisco Bay Area
941 PM PDT Tue May 17 2022

.SYNOPSIS...A warming trend will continue into Wednesday as high 
pressure builds. Temperatures cool a few degrees Thursday as a dry
cold front moves into the Great Basin. This will bring dry 
offshore winds to the region Thursday into Friday with increasing
fire weather concerns. Seasonably warm and dry weather this 
weekend into early next week.

&& of 09:41 PM PDT Tuesday...Temperatures at the 
8pm hour were a few to several degrees warmer than 24 hours ago. 
The atmosphere is warming up as high pressure over the eastern 
Pacific begins strengthening into CA by early tomorrow morning. 
Daytime highs tomorrow will see widespread upper 80s to low 90s 
across the interior putting many inland locations 10-15 degrees 
above normal for mid May. 

By Thursday, an inside slider (an inland low pressure system from
the north moving southward along CA) will become the next dominant
synoptic feature. Breezy to moderately gusty offshore winds are 
still on track for Thursday evening into early Friday morning. 
Latest NAM and WRF are indicating that the window for strongest 
offshore winds will start around 8-10 pm Thursday and then
lessen around 6-8 am Friday. This is a good reminder that we're
getting into that time of year where folks need to be alert for
upcoming fire weather conditions as winds, lower humidity, and
drying fuels are approaching near critical conditions. 


.PREV of 12:55 PM PDT Tuesday...Skies are sunny this
afternoon region wide except for a few wisps of stratus for 
coastal Monterey county. 24 hour trends show most areas about 3-6 
degrees warmer this afternoon compared to Mondays cool 
temperatures. Expect to see some coastal low clouds reform 
overnight as the ridge of high pressure builds and compresses the 
marine inversion layer. 

For Weds the main forecast theme is for continued warming trend,
especially inland areas as upper 80s and lower 90s return to the
forecast as high pressure over the East Pac builds towards our

On Thursday an inside slider moves into the Great Basin. Enough
cool advection for temps to cool a few degrees but the main
impacts will be lowering humidity and increasing dry northerly
winds. Though the strongest winds should stay confined to the
hills above 1500 feet and the far East Bay interior valleys.

On Thursday evening the strongest pulse of offshore winds will
arrive with gusts in the 40-50 mph range for the Napa hills and
Mt Diablo. Right now the best alignment for critical fire weather
concerns looks to stay over the Central Valley. That being said
fire weather concerns will be on the increase over the Bay Area.
At the very least fuels will begin to rapidly dry over the next
few days with breezy conditions always a concern as humidities
lower under dry northerly flow.

North winds ease on Friday as the strongest winds ease followed by
very low humidity values for the interior areas, down in the
teens. Will continue to consider if any wind advisories or fire
weather products are needed but for now will use generic headlines
in the Fire Wx forecasts. Anecdotally the synoptic setup is 
similar to the May 2008 Summit fire in the Santa Cruz mountains so
do your part and be one less spark.

A nice Bay Area weekend in store with seasonably warm temperatures
inland and mild at the coast. Latest deterministic ECMWF suggests 
general warming and drying next week with periods of offshore 
winds possible. Cluster analysis still showing about a 30 percent 
chance of trough solution towards the end of next week but either 
way no rain in the forecast.

&& of 11:10 AM PDT Tuesday...For the 18Z TAFs. VFR
through the TAF period for all but the Monterey Bay, which will see 
MVFR CIGs linger into the afternoon and return late tonight. Winds 
will become breezy to gusty through the evening, but will begin to 
reduce into the night. Most areas offer light to moderate wind 
overnight. Lower clouds will move inland around the Monterey Bay in 
the late night with low clouds lingering into mid Wednesday morning. 
Wednesday looks to be another breezy day region-wide with gustier 
conditions around SFO.

Vicinity of KSFO...VFR through the TAF period. Westerly winds will 
become strong and gusty this afternoon and last through the evening. 
Late night winds will stay breezy but will reduce into the early 
morning. Gusty conditions return around the midday Wednesday and 
look to last through the evening again.

KSFO Bridge Approach...Similar to SFO.

Monterey Bay...Becoming VFR with moderate to breezy winds this 
afternoon. Winds will reduce and become lighter overnight as stratus 
begins to build in the Monterey Bay. Expect MVFR at MRY in the late 
night through the mid morning before VFR returns. 

&& of 09:11 PM PDT Tuesday...Northwesterly gale force
wind gusts will persist across the coastal waters through much of
the week. Strong and gusty winds  will also prevail across the the
San Francisco and Monterey Bay  each afternoon and evening through
midweek. Strong winds will  generating steep fresh swells.


     .Tngt...GLW...Pt Arena to Pt Reyes 0-10 nm
             GLW...Pt Reyes to Pigeon Pt 0-10 nm
             GLW...Pigeon Pt to Pt Pinos 0-10 nm
             GLW...Pt Pinos to Pt Piedras Blancas 0-10 nm
             GLW...Pt Arena to Pigeon Pt 10-60 nm
             GLW...Pigeon Pt to Pt Piedras Blancas 10-60 nm
             SCA...Mry Bay




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Prepared by Weather at: Tue May 17 22:30:02 PDT 2022
From the National Weather Service