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Area forecast discussion 
National Weather Service San Francisco Bay area
153 PM PDT Sat Sep 24 2016

..very warm to hot weather conditions Sunday and Monday...

Synopsis...a strong ridge of high pressure over the region and weak
offshore flow will result in very warm to hot conditions through the
weekend and into Monday. In addition, mostly sunny conditions will
prevail region-wide. A cooling trend is then forecast for the second
half of next week.

&&

Discussion...as of 01:52 PM PDT Saturday...a warm and dry air
mass is in place over the region this afternoon as high pressure
builds in from the eastern Pacific. This has resulted in
temperatures running 5 to as much as 15 degrees above those 24
hours ago along with clear skies region-wide. However, a slight
onshore flow has caused temperatures to cool by a few degrees near
the coast and will limit coastal warming for today. Meanwhile,
inland areas will continue to warm into the upper 80s to lower 90s
while coastal areas experience mid 60s to lower 80s away from the
immediate coastline.

The warming and drying trend will continue into Sunday and Monday as
the ridge builds closer to the California coast and temperatures
aloft warm. In addition, weak offshore flow is forecast through
early tomorrow afternoon and will allow for the warm inland
temperatures to extend to the coast. Have increased temperatures by
a few degrees region-wide for Sunday with upper 80s to low 90s
briefly possible even in downtown San Francisco and around the
Monterey Bay. Temperatures near the coast will greatly depend on
when/if the sea-breeze develops during the afternoon hours the next
few days. Widespread 90s are also forecast for inland areas with
some of the warmest locations reaching into the 100-105 degree
range. In addition to the weak offshore flow and warm temperatures,
sunny skies will prevail through early next week. The forecast
models are no longer showing much relief from the heat on Monday as
weak offshore flow continues and onshore winds do not return early
enough to cool coastal temperatures until Tuesday. With this, a heat
advisory continues for the entire forecast area from 11 am to 8 PM
PDT for both Sunday and Monday. On the flip side, overnight
conditions will cool into the 50s each night and allow for relief
from the daytime heat.

Onshore flow is forecast to increase slightly by Tuesday and allow
for coastal temperatures to cool some while inland areas remain
above seasonal averages. The cooling trend will then spread inland
through the second half of next week as the ridge shifts eastward
ahead of an approaching mid/upper level trough to our northwest. By
late week, daytime temperatures will likely cool as much as 20
degrees compared to Monday. Dry weather conditions are also forecast
through the entire work week ahead with the potential for coastal
clouds to return as early as Tuesday night and Wednesday morning.

&&

Aviation...as of 11:05 am PDT Saturday... high pressure will
bring VFR conditions with clear skies and light winds today.
Afternoon sea breeze up to around 10-20 knots along the coast.

Vicinity of ksfo...VFR. Light winds, except this afternoon where
winds may increase to 15-18 kt. Occasional gust to mid 20 kts
posbl.

Sfo bridge approach...similar to ksfo.

Monterey Bay terminals...VFR through the period. Generally light
winds with a weak afternoon sea breeze.

&&

Fire weather...as of 3:30 am PDT Saturday...latest models
continue to trend towards stronger offshore winds tonight and
Sunday morning, especially in the North Bay mountains. 00z WRF
model forecasts sustained north to northeast winds of 30 mph with
gusts as high as 45 mph across the higher ridges of northern Sonoma
and Napa counties late tonight through Sunday morning. In
conjunction with these winds will be very warm to hot daytime
temperatures and little or no nighttime humidity recovery.
Therefore, a red flag warning will be issued for the North Bay
mountains (fire weather zone 507). The red flag warning will be in
effect from 9 PM Saturday evening until 3 PM Sunday. Otherwise,
expect the warming and drying trend to continue into Sunday and
Monday across the entire district. Winds will generally be light
after Sunday. A cooling trend will begin on Tuesday.

In the vicinity of the soberanes fire: portable RAWS stations
above 3000 feet are currently reporting northeast winds of 10 to
15 mph with gusts up to 20 mph. Winds in this area are forecast to
decrease slightly by this afternoon and then gradually turn to the
south tonight and to the southwest by Sunday afternoon when they
will increase slightly again. Wind speeds are not expected to
increase much beyond their current magnitude through the
remainder of the weekend, however temperatures will climb through
Sunday while relative humidity values drop into the single digits. Hot and very
dry conditions will then continue through Monday. In fact, Monday
will probably be the warmest and driest day, with gradual
improvement expected to begin on Tuesday.

&&

Climate...here are the record highs for September 25 and
September 26.

September 25 September 26
record/year record/year
Bay area

Kentfield.............100/1964.....................99/1921
San Rafael............100/1964.....................99/1963
Napa..................101/1960....................105/1963
San Francisco..........93/1954.....................94/1992
sfo....................91/1970.....................95/1958
Oakland museum.........95/1978.....................93/1973
Oakland Airport........94/2010.....................97/1958
Richmond...............95/1964.....................95/1963
Livermore.............101/1978....................103/1952
Mountain View..........91/1978.....................95/1999
San Jose...............97/1952.....................98/1963
Gilroy................106/1978....................104/1963

Monterey Bay area

Monterey...............95/1954.....................98/1970
Santa Cruz............100/2010....................101/1970
Salinas................97/1960....................100/1970
Salinas Airport........99/1937.....................99/1970
King City.............105/1975....................105/1963

&&

Marine...as of 10:54 am PDT Saturday...a gradually easing
pressure gradient will continue to result in moderate northwest
winds through the day today for most of our waters. The strongest
winds will be this afternoon and this evening along the Sonoma and
Big Sur coasts. Locally generate fresh swell may also result in
hazardous conditions. Winds decrease Sunday.

&&

Mtr watches/warnings/advisories...
... Arena to pt Reyes 0-10 nm until 3 am
Small Craft Advisory...pt pinos to pt Piedras Blancas 0-10 nm until 3 am
Small Craft Advisory...pt Arena to Pigeon pt 10-60 nm

&&

$$

Public forecast: rgass
aviation: drp
marine: drp
climate: BAM
fire weather: dykema



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