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000
FXUS66 KMTR 261206
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco Bay Area
506 AM PDT MON SEP 26 2016

.SYNOPSIS...Strong high pressure over the region and offshore
flow will once again result in extremely warm temperatures over
the San Francisco Bay Area and Monterey Bay Region this afternoon.
Modest cooling is forecast by Tuesday with a more significant
cooling trend expected for the second half of the week as an upper
level trough deepens along the West Coast.

&&

.DISCUSSION...as of 4:28 AM PDT Monday...Heat advisory remains in
effect today with another round of hot temperatures and a good
chance of tying or breaking some more records...or at least making
a good run at them. Not surprisingly most of the trends at this
hour show temperatures running several degrees of where they were
this time yesterday. The sfo-wmc gradient has eased from 14 mb to
9 mb with the northerly gradient down the coast flat so we will
lose some of the ideal adiabatic warming. Either way its splitting
hairs as all signs point to another very warm to hot day. 4 am
readings of 68 in the city and 71 at downtown Oakland portend
another hot day.

So the next forecast challenge becomes when will the cooling trend
begin. We should see at least an inkling of a seabreeze by late
this afternoon and evening as winds briefly turn westerly. We will
lose the offshore winds but not seeing signs of a southerly surge
or significant cooling for Tuesday. Nonetheless expect to see a
few degrees of cooling inland on Tuesday but more noted cooling
only near the coast Tuesday afternoon.

The beaches should get a decent marine push later Tuesday night
into Weds morning. Inland locations will then see much more
dramatic cooling for Weds afternoon. Most places will be 15 to 25
degrees cooler by Weds compared to this afternoon.

ECMWF solution then brings a fairly cool trough down the west
coast the second half of the week...sending temperatures below
normal Thursday through Saturday. However, no precipitation is
forecast with the trough with all long range guidance still
keeping things dry into October.

&&

.AVIATION...As of 5:00 AM PDT Monday...Strong upper level high
over the area. Offshore flow has diminished but lack of onshore
flow will keep VFR clear conditions.

Vicinity of KSFO...VFR.

SFO Bridge Approach...VFR.

Monterey Bay Terminals...VFR.

&&

.FIRE WEATHER...As of 4:28 AM PDT Monday...For Sawmill fire
expect another hot and dry day but the offshore breezes are
easing. Winds will be like a turnstile turning light southerly
this afternoon...then light offshore/northeast again tonight. Very
warm temps well into the 90s with humidity in the teens. Only
subtle cooling Tuesday with any significant cooling holding off
until Weds.

Soberanes Fire...not expecting any of the strong southerly winds
that were observed Sunday. Current trends show temps starting out
today much warmer and drier with single digit humidity already in
place. Expect over 100 degrees for Tassajara and Arroyo Seco and
mid to upper 90s even for portions of the West ops. Really no
changes of note on Tuesday with perhaps a few degrees of cooling
but still dry. Will need to wait until Weds for any appreciable
inland cooling but even that will be moderated for the interior
portions of the fire/forest.

&&

.CLIMATE...Here are the record highs for September 26.

                   September 26
                   Record/Year
Bay Area

Kentfield.............99/1921
San Rafael............99/1963
Napa.................105/1963
San Francisco.........94/1992
SFO...................95/1958
Oakland Museum........93/1973
Oakland Airport.......97/1958
Richmond..............95/1963
Livermore............103/1952
Mountain View.........95/1999
San Jose..............98/1963
Gilroy...............104/1963

Monterey Bay Area

Monterey...............98/1970
Santa Cruz............101/1970
Salinas...............100/1970
Salinas Airport........99/1970
King City.............105/1963

&&

.MARINE...as of 03:46 AM PDT Monday...High pressure covers the
eastern Pacific and the Great Basin while thermal trough lies
along the California coast. The trough will move into the
California interior on Tuesday. Winds will be light and variable
Monday then increase from the northwest Tuesday and Wednesday.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .Tday...Heat Advisory...All zones 11 am to 8 pm

&&

$$

PUBLIC FORECAST: RWW
AVIATION: W Pi
MARINE: W Pi
CLIMATE: BAM/DRP
FIRE WEATHER: RWW


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