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

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000
FXUS66 KMTR 200039
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco Bay Area
439 PM PST Mon Feb 19 2018

.SYNOPSIS...Blustery, cool conditions will persist over the
region today. Sky conditions will clear along with diminishing
winds overnight with widespread freezing temperatures by Tuesday
morning. Cool unsettled weather conditions are then expected
through the remainder of the week and potentially into early next
week as well.

&&

.DISCUSSION...as of 1:21 PM PST Monday...After an active morning
with passing showers and snow showers, afternoon radar imagery
shows much of the activity has all but ended. The exception is
over the coastal waters as a few popcorn showers continue. Not too
surprising giving the temperature difference of SST (low 50s) and
air temps (30s aloft and 40s at sfc). It was not a blockbuster
snow storm for the Central Coast by any means but it did snow none
the less. Spotters and the general public reported a dusting of
snow over portions of the Santa Cruz Mts to several inches of snow
over the Santa Lucia Mts. Despite mostly sunny skies this
afternoon it remains very blustery with temps in the 30s over the
hills and 40s/50s elsewhere and wind gusts still 20-30 mph. The
combination of winds and temps put wind chills in the teens and
20s over the highest peaks.

The biggest weather impact over the next few days is still on
track for tonight. Only minor adjustments were made to previous
forecast. Simply put, tonight will likely be one of the coldest
nights of the winter season thus far. Once the winds diminish
temperatures will plummet impacting not just the interior
locations, but major urban centers and all the way to the coast.
Overnight lows are in the 20s to around 30 deg F. Temperatures
are also forecast to cool into the lower 30s even in many coastal
areas where areas of frost will be possible. Thus, will continue
the Freeze Warning for inland areas and Frost Advisory for coastal
areas from late tonight into Tuesday morning. If you have not
done so already now is the time to take precautions for sensitive
vegetation and protect any exterior pipes. Additionally, if you
have pets outside find them warm shelter.

The very cold broad upper level trough will remain over the region
through Thursday with embedded short-wave troughs. Temperatures
will remain below normal for late February with high and low
temperatures. However, given the passing short-wave troughs enough
cloud cover will likely be present overnight to moderate low
temperatures. Therefore, will not have any frost or freeze after
tonight. That being said, it doesn`t mean temperatures won`t
impact sensitive vegetation or sensitive groups. It means it won`t
be as extreme as tonight. Daytime highs Tuesday through Thursday
will be in the 50s for lower elevations and 30s/40s for the higher
peaks. Overnight lows will be in the upper 20s to lower 30s across
the interior and upper 30s to mid 40s for urban areas and the
coast.

This is where the forecast becomes more tricky and less confident.
Short to medium range develop a little precip with the first
shortwave Tuesday night/Wednesday. Current thinking is most shower
activity will remain over the waters and brush some of the coast.
Snow level remains low so showers and snow showers (2-3k feet)
will be possible. A second and slightly stronger short-wave trough
drops more over the Bay Area Wednesday night through Thursday
night leading to slightly better chance for inland shower
activity. Once again, snow levels remain low so minor
accumulations will be possible over the higher peaks.

A brief moderation of temperatures will be possible next weekend
as weak ridging begins. There after lots of attention will be
focused on next Monday and Tuesday and all three of the long
range models depict a storm system dropping down the coast
bringing widespread precip to the region. Long range models have
been hinting at a storm system impacting the region toward the end
of the month. Stay tuned...

&&

.AVIATION...As of 4:30 PM PST Monday...Radar indicates a shower
moving south across the East Bay briefly affecting OAK. Clouds
and showers will diminish by evening for VFR conditions. Winds
gusting to 30 kt decreasing rapidly after 03Z.

Vicinity of KSFO...VFR. West winds gusting 25-30 kt through 04Z.

SFO Bridge Approach...Similar to KSFO.

Monterey Bay Terminals...VFR with a few cumulus clouds through
04Z. West winds gusting to 25 kt through 04Z.

&&

.CLIMATE...

Here are record low temperatures and the years they occurred for
Monday through Wednesday this week.

Location          Monday          Tuesday          Wednesday

SF Bay Area

Healdsburg        28 in 1932      22 in 1922       28 in 1929
Santa Rosa        26 in 1932      26 in 1913       26 in 1913
Calistoga         25 in 1918      25 in 2006       25 in 2006
Kentfield         27 in 1932      27 in 1913       29 in 1953
San Rafael        32 in 1990      32 in 2006       33 in 1955
Napa              29 in 1990      28 in 1920       29 in 1955
San Francisco     38 in 1897      38 in 1897       36 in 1890
SFO Airport       36 in 1990      37 in 2011       34 in 1955
Half Moon Bay     34 in 1954      32 in 2013       31 in 2006
Oakland Airport   35 in 1955      34 in 2006       33 in 1955
Richmond          35 in 1990      35 in 1990       35 in 1981
Livermore         27 in 1956      28 in 1942       27 in 1955
Moffett Field     35 in 1949      34 in 2006       32 in 1955
San Jose          32 in 1990      30 in 1897       25 in 1897
Gilroy            27 in 1964      30 in 1990       31 in 1976

Monterey Bay Area

Santa Cruz        30 in 1990      29 in 1913       30 in 1955
Salinas           29 in 1990      31 in 2006       31 in 1970
Salinas Airport   29 in 1933      28 in 1953       30 in 1953
Monterey          35 in 1990      35 in 2006       36 in 1952
King City         25 in 1955      22 in 1953       23 in 1953

&&

.MARINE...as of 04:01 PM PST Monday...Strong northwest winds will
continue to generate fresh swell and  steep wind waves through
tonight. Winds will decrease slightly overnight, but remain
moderate. Another trough will swiftly move  southward over the
coastal waters late Wednesday night, increasing winds and will
also introduce a slight chance of rain.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .Tngt...Freeze Warning...All interior locations
             Frost Advisory...Coastline from Sonoma to Monterey
                              including Bay Shoreline, but not SF
                              Cty.
             SCA...Pigeon Pt to Pt Pinos 0-10 nm
             SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm
             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 from 3 AM
             GLW...Pt Arena to Pigeon Pt 10-60 nm until 3 AM
             GLW...Pigeon Pt to Pt Piedras Blancas 10-60 nm until 3 AM
             SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm from 3 AM
             SCA...Rough Bar Advisory for SF Bar until 8 PM
             SCA...SF Bay until 3 AM
             SCA...Mry Bay until 3 AM

&&

$$

PUBLIC FORECAST: MM
AVIATION: W Pi
MARINE: BAM

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