FXUS66 KMTR 231205
Area Forecast Discussion
National Weather Service San Francisco Bay Area
505 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 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 05:05 AM PDT Thursday...Strong northerly
gradient continues with limited intrusion of stratus inland. Areas
to the north of the Golden Gate and inland locations have
remained mainly VFR overnight while points south near the coast
have seen extensive MVFR/IFR cigs. Latest satellite and surface
observational trends indicate stratus expanding around the
southern SF Bay as high clouds decrease. Stratus may at times
bring MVFR cigs to SFO and OAK through mid to late morning.
Onshore winds expected this afternoon at 10-15 kt with VFR
conditions this afternoon through early evening.
Vicinity of KSFO...A patch of MVFR cigs have developed over the
terminal early this morning. Occasional MVFR expected to affect
the terminal through 16z. West-northwest winds will strengthen
this afternoon with speeds of 10-15 kt. Winds may gain a
southwesterly component this evening continuing overnight. VFR
expected through the evening with MVFR returning overnight.
SFO Bridge Approach...Similar to KSFO, except satellite shows less
coverage of stratus over the approach. Stratus may fill in with
MVFR cigs at times through mid morning.
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 03:26 AM PDT Thursday...Low pressure over the
California interior will move into the Great Basin on Thursday.
Strong northwest winds on the back side of the low including gale
force winds over the northern waters will decrease Thursday night.
Strong 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.
.Tday...High Surf Advisory...CAZ006-505-509-529-530
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
SCA...Mry Bay until 3 PM
PUBLIC FORECAST: RGass
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