Mine looks to be good (in English) 000
FXUS66 KMTR 021616
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco Bay Area
916 AM PDT Fri Nov 2 2018
.SYNOPSIS...Another mild day across the Bay Area as high pressure
remains off the California Coast. Offshore flow will increase
Friday night into Saturday with decreasing humidity. In the longer
range, dry conditions, warmer than normal temperatures, and
periods of offshore winds are forecast to continue through next
week. Some hints of possible rain chances by Veterans Day Weekend.
&&
.DISCUSSION...as of 09:10 AM PDT Friday...Upper level ridge has
flattened somewhat overnight in response to a shortwave trough
moving through the Pacific Northwest. The North Bay and locations
along the coast will see slight cooling due to the trough while
other areas will see similar temperatures to yesterday with highs
above normal. Currently seeing a narrow band of stratus just off
the coast from Pt. Reyes southward. However the stratus is
pushing onshore locally near San Francisco and Half Moon Bay.
Main weather impact/focus today will be on Fire Weather
conditions tonight through Sunday morning. The trough will act to
increase offshore flow as a surface high builds into Oregon and
Great Basin while lower pressure remains along the coast. The
offshore flow will bring in very dry air especially to the higher
terrain. The strongest winds will be between 12-18Z Saturday
morning over the higher terrain of Napa and eastern Sonoma
Counties and the East Bay Hills. Relative humidity will drop to
critically low values in these areas with RH in the single digits
possible during the day on Saturday. Please see the previous
discussion and Fire Weather section for more details. No updates
planned this morning.
&&
.PREV DISCUSSION...as of 2:58 AM PDT Friday...Main weather
impacts to the Bay Area over the next seven days will be Fire
Weather focused with another offshore flow event.
The broad high pressure parked off the California Coast will
flatten a little today as a disturbance pushes into Pac NW. The
aforementioned disturbance can easily be seen on the water vapor.
So what does this mean for the Bay Area? Two things, slight
cooldown and setting the stage for offshore flow. In the short
term, expect another mild day around the Bay Area with widespread
70s and 80s. The flattening ridge will bring subtle cooling to the
immediate coast, but despite the cooling the temps will remain
above normal. The passing disturbance will push through today and
early tonight. In its wake surface high pressure will build over
Oregon and eventually portions of the Great Basin. This is a
classic set up for offshore over the Bay Area - inland high
pressure and lower pressure at the coast. Latest forecast pressure
gradients peak a little under 10mb from SFO-WMC by Saturday
morning. Lack of strong upper level support and moderate surface
gradients will likely put this event in the moderate category.
None the less there will still be impacts from a fire weather
stand point and less of a widespread wind impact event.
Now for the details - 00Z hi-res models ramp up N to NE winds
across the higher terrain 06Z Saturday with the peak winds 12-18Z
Saturday. Winds of 15 to 30 mph with gusts 40-50 mph and locally
up to 50-60 mph. The 50-60 mph gusts will be possible at places
like Mt Diablo, Mt Saint Helena, Geyser Peak and Atlas Peak. As
the N/NE flow kicks in relative humidity will tumble and become
critically low. In fact, some models suggest single digit humidity
readings during the day Saturday. Therefore, upgraded the Fire
Weather Watch to a Red Flag Warning to account for the gusty
offshore flow and low relative humidity. If a fire gets started it
will easily spread under these conditions. The offshore flow will
also lead to even warmer temperatures on Saturday with widespread
80s across the interior.
Winds will gradually diminish late Saturday night into Sunday, but
the lack of humidity recovery will keep the fire weather threat in
place. Onshore flow returns on Sunday leading to a cooling trend.
As for next week, general high pressure remains off the California
Coast with periods of weak northerly flow. The storm track remains
to the north with mild and dry conditions.
Given another round of fire weather concerns the next logical
question would be, where`s the rain? There is some hope as longer
range models continue to indicate a patter shift and southern drop
of the storm track Nov 10-12. Lots can happen between now and
then, but will have to watch the pattern evolve.
&&
.AVIATION...as of 5:02 AM PDT Friday...A dry northerly flow and a
compressed marine inversion continues. Stratus and fog is brushing
the San Mateo Coast and more stratus far upstream is rounding the
corner of Cape Mendocino. Fog has reduced the visibility to less
than 1/4 mile /VLIFR/ and ceiling 200 feet at KHAF. The stratus
near Cape Mendocino is with a discontinuous and shallow cool
frontal boundary that`ll eventually sweep southward to the Central
Coast by early Saturday morning; patchy stratus and fog will remain
possible on the immediate coastline, otherwise it`ll be VFR.
WRF model forecasts marginal low level wind shear over the Bay
Area terminals Saturday morning.
Vicinity of KSFO...VFR. Light wind becoming NW-W 10 to 12 knots
this afternoon. Light wind late tonight, low level wind shear
forecast 12z-18z Saturday.
SFO Bridge Approach...Similar to KSFO.
Monterey Bay Terminals...VFR. Light E-SE winds except near 10 knots
in the Salinas Valley this morning. Wind becoming onshore 5 to 10
knots this afternoon shifting back to light E-SE tonight.
&&
.FIRE WEATHER...as of 3:15 AM PDT Friday...Fire Weather Watch has
been upgraded to a Red Flag Warning for late tonight through early
Sunday morning. The greatest impacts where fire weather conditions
will be most critical will be to locations above 1,000 feet for
the North Bay Mountains and East Bay Hills. Hi-res models have
really honed in on increasing winds after about 11 PM Friday and
peaking during the afternoon on Saturday. Winds will diminish
gradually Saturday night. Humidity values will recovery early
Friday night then drop through sunrise Saturday as NE flow kicks
in. Further drying is expected during the day Saturday with RH
dropping into the single digits. Winds may diminish Saturday
night, but RH recovery will remain poor and less than 30%. It
should be noted that even though the Santa Cruz Mts, Santa Lucia
Mts and southern Gabilan are not technically in the Red Flag
Warning, those locations will be near critical levels, just not as
as windy.
&&
.MARINE...as of 9:10 AM PDT Friday...Northerly winds will
increase across the coastal waters today and tomorrow. Winds will
remain gusty through early next week before gradually diminishing.
These winds will generate steep wind waves and fresh swell
resulting in hazardous seas conditions, especially for smaller
vessels. Mixed northwest and southerly swell will continue through
the forecast period.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
.Tday...SCA...Pt Reyes to Pigeon Pt 0-10 nm from 3 PM
SCA...Pigeon Pt to Pt Pinos 0-10 nm from 3 PM
SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm from 3 PM
SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm from 3 PM
SCA...Pt Arena to Pigeon Pt 10-60 nm
SCA...Pt Arena to Pt Reyes 0-10 nm from 9 AM
&&
$$
PUBLIC FORECAST: ST/MM
AVIATION: W Pi/Canepa
MARINE: AS
FIRE WEATHER: MM
Visit us at www.weather.gov/sanfrancisco
Follow us on Facebook, Twitter, and YouTube at:
www.facebook.com/nwsbayarea
www.twitter.com/nwsbayarea
www.youtube.com/nwsbayarea