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

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FXUS66 KMTR 230600
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco Bay Area
1100 PM PDT Thu Jun 22 2017

...Hot and dry conditions will continue through Friday...

.SYNOPSIS...Heat Advisories is now in place through 9 pm Friday
for dangerously hot temperatures over the interior and hills. A
shallow marine layer along the Central Coast will keep the
Monterey Bay coastal areas much cooler. Temperatures will still be
hot across the interior for Friday, just not as hot as this
afternoon. Additional cooling will occur over the weekend.

&&

.DISCUSSION...as of 8:59 PM PDT Thursday...Temperatures have cool
slightly from their peak this afternoon however current reading
continue to show inland temperatures in the 90s with a few
locations still over 100 degrees. At 9 pm this evening the
Excessive Heat Warming will be allowed to expire and will be
replace by a Heat Advisory over the interior portions of the East
Bay, Santa Clara County, as well as, the mountains of Monterey and
San Benito County.

Temperatures finished off the day in the 80s and 90 across much of
the region with warmest inland temperatures topping out anywhere
from 100 to 109. Our warmest readings today were Livermore Fire
Department, Pinnacles and Bradley that all shared the honors of
reaching 109 degrees. Climatologically speaking temperatures were
anywhere from 15 to 25 degrees above normal for today however no
record were broken. A return of the onshore flow and a
redeveloping albeit shallow marine layer kept temperatures from
breaking out of the 70s along the immediate coast.

Cooler temperatures are in store for Friday and into the weekend
as the upper level ridge of high pressure, that has brought us
this heat wave, shift east as an upper level trough approaches
from the west. As a cooler airmass approaches the area, onshore
flow strengthens and the marine layer gradually deepens,
temperatures should gradually cool around 10 degrees on Friday.
While cooler temperatures are in the forecast Friday a heat risk
still exists across the interior portions of the East Bay, Santa
Clara county and the mountain of San Benito and Monterey counties.
Please continue to take precaution as children, the elderly and
pets are very sensitive to extreme heat and dehydration. Also with
the high sun angle sunburns and sun poisoning are risks that can
be prevented with sunscreen, hats, and appropriate clothing.

From previous discussion...On Saturday temperatures will perhaps
drop another few degrees as an upper level low begins to nudge
toward the California coast. There could be some mid/upper-level
moisture that advects from the south/southeast that may bring
isolated thunder to our east in the Sierra Nevada. Probability of
precipitation may have to increase over our area if future model
runs continue to push the moisture toward the Central Coast.

Early next week the upper low will push onshore and help to
flatten the Desert Southwest ridge. Temperatures will finally
return closer to normal with highs back to low 80s to low 90s for
the interior East Bay and South Bay. There is even the possibility
that areas could be several degrees below normal by Tuesday.

Again, going back to today, dangerously hot weather is here for
locations away from the coast. While a much welcomed cool down is
will begin tomorrow, temperatures will still be elevated enough to
present heat impacts, especially to those sensitive to the heat.
Take the necessary precautions to beat the heat: drink plenty of
fluids, limit outdoor activity during the hottest time of the
day, wear light-colored clothing, put on a hat. If you don`t have
air conditioning, consider going to a community cooling center, a
shopping center/mall, or movie theater. If you`re parked in the
shade, or even if you`re at the coast with outdoor temperatures in
the 60s: never leave children, pets, or adults alone in a parked
vehicle. Stay safe, stay hydrated, and beat the heat.

&&

.AVIATION...As of 10:55 PM PDT Thursday...For 06z Tafs.
Widespread low clouds and fog have developed along the coastline
and was beginning to move inland by late Thursday evening as the
marine layer deepens. Expect IFR/LIFR conditions at coastal TAF
sites overnight, but there there is uncertainty as to whether low
ceilings will develop around San Francisco Bay. Clearing is
expected in most locations by 18Z Friday. Low clouds will likely
will develop earlier on Friday evening.

Moderate forecast confidence except low confidence on ceilings
overnight at KSFO.

Vicinity of KSFO...Scattered low clouds expected overnight, but
a southerly component to the low level flow should help keep KSFO
VFR overnight. IFR ceilings more likely to develop at KOAK than
KSFO late tonight and into Friday morning. Light westerly winds
overnight, becoming moderate on Friday afternoon.

SFO Bridge Approach...Similar to KSFO.

Monterey Bay Terminals...IFR/LIFR ceilings overnight and into
Friday morning with areas of MVFR vsbys. Clearing expected by
17-18Z Friday. Light winds.

&&

.FIRE WEATHER...As of 9:00 PM PDT Thursday...Although onshore
flow has returned, the marine layer will remain shallow and the
airmass aloft will remain very warm for a few more days. Thus,
conditions in the hills will only gradually improve from Friday
through the weekend. Much improved conditions are expected by
early next week.

&&

.CLIMATE...

Here is a list of record high temperatures

SF BAY AREA              Thursday
LOCATION.................Temp/Year
 KENTFIELD................102/1989
 SAN RAFAEL................99/2006
 NAPA.....................105/1981
 SAN FRANCISCO.............97/1989
 SFO AIRPORT...............98/1989
 OAKLAND AIRPORT...........94/1957
 RICHMOND..................94/1989
 LIVERMORE................110/1961
 MOFFETT FIELD.............99/1989
 SAN JOSE.................101/1989
 GILROY...................110/1973

MONTEREY BAY AREA        Thursday
LOCATION..............   Temp/Year
 SALINAS...................89/1981
 SALINAS AIRPORT...........92/1947
 KING CITY................110/1929

&&

.MARINE...as of 8:50 PM PDT Thursday...A weak surface low
offshore will maintain light southerly winds over the coastal
waters through Friday. However, moderate and gusty seabreeze winds
are expected during the afternoon and evening hours around the
Golden Gate and Angel Island. Winds over the coastal waters will
shift to the west and northwest on Saturday and then increase on
Sunday. Seas will subside through the remainder of the week and
into the weekend.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .Tngt...Heat Advisory...CAZ510-511-517-518
             SCA...SF Bay until 11 PM

&&

$$

PUBLIC FORECAST: CW
AVIATION: Dykema
MARINE: BAM
FIRE WEATHER: RWW


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