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

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FXUS66 KMTR 230535
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco Bay Area
1035 PM PDT Mon Jul 22 2019

.SYNOPSIS...A gradual warming trend will continue through midweek,
especially across the interior. This will lead to seasonably warm
temperatures inland while coastal areas remain mild under the
influence of a shallow marine layer and persistent onshore flow.
No significant changes are expected through the end of the week or
into next weekend, except the possibility of even warmer inland
temperatures during the weekend.

&&

.DISCUSSION...As of 9:00 PM PDT Monday...The warming trend that
got underway yesterday became more widespread today, with nearly
all locations having warmer temps today than yesterday. Areas very
close to the ocean saw temperatures near persistence. There was a
44 degree difference between the coolest and warmest high
temperature in our forecast area today: from 58 at Ocean Beach in
San Francisco to 102 at Pinnacles National Park.

A shallow marine layer is resulting in patchy dense fog in coastal
areas this evening. A weather spotter recently reported visibility
of less than a quarter mile just to the east of Santa Cruz.
Patchy dense fog will likely continue to be an issue during the
night and morning hours through the rest of the week.

The upper level ridge centered near the Four Corners will continue
to be the dominant weather feature across the southwestern third
of the nation for the remainder of the week and into the upcoming
weekend. However, the ridge is expected to weaken slightly (and
briefly) over northern California tomorrow as as an upper trough,
currently centered offshore along 135W, lifts to the northeast
and into the Pacific Northwest. Thus, the warming trend will
likely stall tomorrow, and we may even see a few degrees of
cooling in some locations.

The warming trend will recommence on Wednesday as the ridge
strengthens once again over northern California. Most warming will
continue to be across inland areas where Wednesday`s highs could
be as much as 10 degrees warmer than normal. A shallow marine
layer will persist, as will onshore flow, and so areas close to
the ocean will likely experience only a few degrees of warming.

Most model guidance indicate that Wednesday will be the warmest
day of the work week and that temperatures will fall back slightly
for Thursday and Friday, but still remain very warm inland. We may
also see some mid and upper level cloud cover from late Wednesday
through early Friday as monsoon moisture rotating around the Four
Corners High tracks across California. Models forecast a very weak
shortwave trough rotating around the ridge, coincident with the
mid and upper level moisture, and this will be something to keep
an eye on for potential high-based showers and/or thunderstorms,
mainly for Thursday night.

The longer range models, including the ensemble mean from both the
ECMWF and GFS, agree that the center of the upper ridge will
shift westward and over southern California during the upcoming
weekend. This would likely result in renewed warming on Saturday
and Sunday. The ECMWF forecasts more robust weekend warming
compared to the GFS. Our current forecast more closely follows the
GFS. Projected Heat Impacts through the remainder of the week and
into the weekend, based on the current forecast, are mostly in
the low to moderate categories. However, heat impacts could
ratchet up into the high category for some inland areas next
weekend if the ECMWF forecast is correct.

&&

.AVIATION...as of 10:35 PM PDT Monday...The marine layer remains
steady at 1200 ft this evening with status only covering the coast
from Santa Cruz south. Anticipate a return of stratus overnight
to KMRY and KSNS with all other terminals remaining clear.
Moderate onshore flow will continue to ease becoming light and
locally variable overnight.

Vicinity of KSFO...VFR conditions will prevail through the
forecast period. Onshore flow will continue to ease becoming
light around 5 to 10 kt overnight.

SFO Bridge Approach...Similar to KSFO.

Monterey Bay Terminals...LIFR cigs will prevail through tonight.
Clearing is anticipated around 17z Tuesday morning. Light and
locally variable winds expected overnight.

&&

.MARINE...as of 8:58 PM PDT Monday...Breezy northwest winds will
persist through Tuesday across the coastal waters. Winds will
increase becoming gusty Tuesday night and Wednesday as high
pressure builds into the Pacific Northwest and northern
California. Light southerly swell coupled with short period wind
waves will continue through the week.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .Tngt...SCA...Pt Arena to Pt Reyes 0-10 nm
             SCA...Pt Reyes to Pigeon Pt 0-10 nm
             SCA...Pt Arena to Pigeon Pt 10-60 nm
             SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm
             SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm from 3 AM

&&

$$

PUBLIC FORECAST: Dykema
AVIATION: CW
MARINE: CW

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