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

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FXUS66 KMTR 261217

Area Forecast Discussion
National Weather Service San Francisco Bay Area
517 AM PDT Sun May 26 2019

.SYNOPSIS...Light rain will move through the area during early
morning hours, with gusty west to northwest winds developing near
the coast. Rain will change to showers along with isolated
thunderstorms today along with unseasonably cool daytime
temperatures. Dry but cool conditions are forecast for Memorial
Day. A gradual warming trend is expected early next week with
temperatures expected to return to near normal by midweek.


.DISCUSSION...As of 3:07 AM PDT Sunday...KMUX is showing a band
of light rain moving from north to south across the CWA, with rain
currently occurring in Monterey. Rainfall totals thus far have
generally been under a tenth of an inch. This rain band is the
frontal band associated with a cold upper level low that is moving
south along the coast. Winds behind this front are increasing
from the northwest with gusts in the 20 to 30 mph range. The cold
air behind this front, along with the upper low, will initiate
scattered showers across the district along with the possibility
of thunderstorms throughout the day. By late morning, the upper
low is progged to be located over the San Francisco Bay Area. This
placement will give the greatest precip potential to the southern
half of the district where up to a half inch of rain is possible,
most across the coastal ranges.

High temperatures today are forecast to range from the mid 50s to
mid 60s...with cooler readings expected in the hills. These
temperatures will be as much as 20 degrees cooler than normal for
late May. Snow levels dropping to as low as 4500 feet could bring
light snowfall accumulations to the higher peaks and ridges of
the Santa Lucia Mountains in Monterey County. There may even be
brief light snow at the summit Mount Hamilton.

The upper low will then move to the southeast overnight with
northwest winds decreasing and showers ending by morning. Memorial
Day is expected to be mostly dry and warmer as high pressure
begins to build along the coast. This ridge of high pressure will
usher in a warming trend through the rest of the week with high
temperatures returning to near normal for this time of year.

&& of 5:17 AM PDT Sunday...Unseasonably cold upper
low continues to move rapidly southward through the northern half
of the district. Gusty northwest winds at many Bay Area terminals
including strong and gusty winds approaching 50 mph per mesowest
obs in the North Bay mountains and East Bay Hills/Mtns. Low level
wind shear indicated in KSTS taf until 17z this morning. Expect
additional showers and the potential for isolated thunderstorms
including small hail. Late May, increased seasonal angle of solar
incidence surface warming combined with any brief clearing will
tend to boost rather modest model forecast buoyancy (CAPE several
hundred j/kg) potential higher mitigated somewhat by slightly
lowering dewpoint temperatures for a period of time through late
morning; not to underestimate today`s potential for nearly ideal
convective overturning it`s worthy of close monitoring throughout
the day. Slightly elevated precip water values arrive late today
and tonight in the atmospheric column per recent GFS output, wet
weather today moistening the boundary layer along with lighter
winds tonight could bring about a patch or two of fog early Monday

Vicinity of KSFO...MVFR, gusty west winds through morning at least,
winds tapering off in the afternoon. Showers. Possible thunderstorms
in the Bay Area today, will closely monitor radar and obs and will
add VCTS to KSFO taf if needed.

SFO Bridge Approach...Similar to KSFO.

Monterey Bay Terminals...MVFR-VFR, gusty west winds today. Showers
as the upper low sweeps by later this morning and early afternoon
a few thunderstorms are possible.

&& of 2:30 AM PDT Sunday...Unseasonably chilly weather
for late May is arriving this morning on gusty northwest winds.
Unstable atmospheric conditions will result in showers and
isolated thunderstorms through today. Moderate northwest swell
continues through the weekend with steep fresh seas generated by
gusty winds.


     .Tday...SCA...Pigeon Pt to Pt Pinos 0-10 nm
             SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm
             SCA...Pt Arena to Pigeon Pt 10-60 nm
             SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm
             SCA...Pt Arena to Pt Reyes 0-10 nm
             SCA...Pt Reyes to Pigeon Pt 0-10 nm
             SCA...Rough Bar Advisory for SF Bar
             SCA...SF Bay until 3 PM
             SCA...Mry Bay until 3 PM




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