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NWS Forecast Area Discussion - San Francisco Area

000
FXUS66 KMTR 231733
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco Bay Area
1033 AM PDT Thu May 23 2019

.SYNOPSIS...Temperatures will remain near to slightly below seasonal
averages through late week with mainly dry weather conditions.
Unseasonably cool and unsettled conditions return late in the
weekend with chances for rain showers as a weather system drops down
the West Coast.

&&

.DISCUSSION...as of 8:46 AM PDT Thursday...Visible satellite
imagery shows both some low and high clouds over the San Francisco
Bay Area and central California coast this morning. Temperatures
are running about 2 to 5 degrees warmer compared to 24 hours ago
as the atmospheric column has moderated with the departing upper
level low. Despite the warmer temperatures expected this afternoon
(60s along the coast, 70s inland), we will still be running about
2 to 7 degrees below our middle to late May climatological normal
highs. Can`t rule out a stray shower developing this afternoon in
the Gabilan Range, but think the best chances for showers (and
thunderstorms) will be confined to our east in the Sierra Nevada.
No forecast updates are anticipated at this time. For additional
details, please refer to the previous discussion section.

&&

.PREV DISCUSSION...as of 03:26 AM PDT Thursday...High clouds continue
to stream over the region this morning as the core of an upper
level low spins over western Arizona. With the main trough axis
also well inland, low clouds have returned to many coastal areas
from the San Francisco Peninsula down along the Central Coast
penetrating inland into the Salinas Valley. With this and a
moderate air mass aloft, temperatures are slight warmer compared
to previous mornings. Looking for mainly dry conditions this
afternoon with temperatures warming into the 60s near the coast to
70s inland. However, cannot rule out an isolated shower or two
developing over the Gabilan Range this afternoon during peak
daytime heating as a weak disturbance rotates along the western
periphery of the trough.

Little change is anticipated for Friday and Saturday as a broad
trough remains over the western portion of the country. Should see
night/morning clouds near the coast working locally inland before
giving way to partly cloudy conditions in the afternoon. Again,
temperatures will remain slightly below seasonal averages with 60s
near the coast to 70s inland during the afternoon hours with
Saturday being slightly cooler than Friday.

Another mid/upper level low is then forecast to drop southward out
of Alaska and British Columbia late this weekend. As the low travels
down the West Coast chances for rain showers develop over the region
by Sunday. Systems such as this typically are moisture starved, so
widespread rainfall is unlikely. However, isolated to potentially
scattered showers cannot be ruled out late in the weekend and
potentially into early Monday. While a total "wash out" is unlikely
for the Memorial Day Holiday Weekend, unsettled conditions will
continue with unseasonably cool temperatures and potential for
lingering showers. Warmer and drier weather conditions are forecast
for the middle part of next week as the mid/upper level trough
finally shifts inland.

&&

.AVIATION...as of 10:27 AM PDT Thursday...Morning low clouds were
slow to clear given high clouds overhead. Most terminals are VFR
now with the exception of Monterey Bay. MRY/SNS will gradually
clear late this morning. VFR this afternoon with high clouds.
Clouds return this evening. Some models suggest a semi-southerly
surge up the coast. Clouds inside SF Bay will be low confidence
forecast tonight.

Vicinity of KSFO...VFR as clouds clear. Breezy to gusty winds
possible this afternoon. Will bring a BKN deck back late tonight,
but confidence is marginal.

SFO Bridge Approach...Similar to KSFO. Possibly less clouds late
tonight compare to KSFO and KOAK.

Monterey Bay Terminals...IFR this morning with patchy drizzle
observed at the terminals. Expect IFR conditions to improve to
MVFR by late morning, and then VFR early this afternoon. MVFR cigs
returning early this evening.

&&

.MARINE...as of 10:23 AM PDT Thursday...Moderate to locally strong
winds will persist over the coastal waters today and early tonight
resulting in hazardous conditions. Winds will gradually decrease
late tonight and early Friday.  Gusty northwest winds will
redevelop over the coastal waters  Friday night through the
weekend. A large northwest swell will  persist through the end of
the week and into the weekend  particularly over the northern and
outer waters.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .Tday...SCA...Pt Arena to Pt Reyes 0-10 nm
             SCA...Pt Reyes to Pigeon Pt 0-10 nm
             SCA...Pigeon Pt to Pt Pinos 0-10 nm
             SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm
             GLW...Pt Arena to Pigeon Pt 10-60 nm until 3 PM
             SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm
             SCA...Rough Bar Advisory for SF Bar

&&

$$

PUBLIC FORECAST: Rowe/RGass
AVIATION: MM
MARINE: MM

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NWS MTR Office Area Forecast Discussion

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