Preview of NWS' New Version of Forecast
This preview is not operational and should not be used for support decisions.

Area Forecast Discussion (AFD)

Issued by San Francisco Bay Area, CA (MTR)

FXUS66 KMTR 182328

Area Forecast Discussion
National Weather Service San Francisco Bay Area
328 PM PST Mon Feb 18 2019

.SYNOPSIS... Cool, dry weather conditions are forecast to persist
along with cold overnight temperatures through Wednesday morning.
Another cold weather system is forecast to bring light rain 
showers to the region Wednesday into Thursday morning with snow 
likely in the higher elevations. Dry conditions return late 
Thursday and persist into at least Friday. 

&& of 01:42 PM PST Monday...Mainly clear sky 
conditions prevail over the region this afternoon with 
temperatures ranging from the 50s in the major urban areas into 
the 20s/30s in the region's highest peaks where snow remains on 
the ground. Visible satellite imagery shows the greatest snowfall 
over around Rose Peak and Mt. Hamilton down into the southern 
portion of the Diablo Range as well as the highest peaks of the 
Santa Lucia Mountains and Sierra de Salinas. 

With light winds and clear sky conditions again tonight, 
temperatures will cool into the 30s for most to around 40 in San 
Francisco and along the immediate coast by Tuesday morning. Cannot 
rule out areas of frost for inland locations and even patchy fog in 
portions of the East Bay Valleys as well as in the southern Santa 
Clara Valley around sunrise. Daytime temperatures on Tuesday look to 
be similar to today as well, generally in the 50s. 

A reinforcing shot of colder air will advect southward down the 
coast Wednesday into Wednesday night with an associated short-wave 
disturbance. This system will likely produce isolated to scattered 
(at best) showers over the region with snow likely in elevations 
above 2,500 feet. Moisture will be limited with this system which 
will prevent more widespread showers. This system may bring 
overnight temperatures up by a few degrees given the increase in 
cloud cover. However, look for cooler than normal values to persist 
through midweek. 

A short-wave ridge will build over the region Thursday night into 
Friday which will result in the return of dry weather. Temperatures 
again change little as broad troughing remains in place over much of 
the western portion of the country. The forecast models differ from 
one another heading into the upcoming weekend with the GFS being 
most promising of additional light rainfall on Sunday. Meanwhile, the 
ECMWF keeps precipitation to our north. Either way, widespread 
precipitation in the extended does not appear likely and 
temperatures look to stay below seasonal averages. 


.AVIATION...As of 03:28 PM PST Monday...For 00Z TAFs. VFR
conditions through the period with mainly clear skies for the SF
Bay Area and Monterey Bay Area terminals. Patchy fog possible in
the North and East Bay tomorrow morning, although any fog that may
develop is not expected to be widespread. Breezy northerly winds
this afternoon with gusts up to 20 kt. Winds should remain light
overnight and through the morning generally less than 10 kt.

Vicinity of KSFO...VFR conditions with mainly clear skies. 
Guidance show increasing high clouds towards the end of the taf 
period. West to northwest winds into this evening, generally 
between 10-15 kt.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals....VFR conditions are forecast to prevail
with light winds. Some southeast drainage winds likely to develop
overnight and early Tuesday at SNS.

&& of 02:31 PM PST Monday...Gusty north to northwest 
winds will gradually subside overnight before increasing again 
during the day on Tuesday. Lighter winds are forecast in the bays.
The northwest swell will gradually subside over the next 24 hours
before a longer period moderate northwest swell train arrives 


     .Tngt...SCA...Pigeon Pt to Pt Pinos 0-10 nm until 9 PM
             SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm until 9 PM
             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




Visit us at

Follow us on Facebook, Twitter, and YouTube at: