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 191134

Area Forecast Discussion
National Weather Service San Francisco Bay Area
434 AM PDT Thu Sep 19 2019

.SYNOPSIS...Seasonably cool conditions will persist on Thursday
followed by a warming trend forecast through the upcoming weekend.
A low pressure system moving southward to our east early next week
may create the potential for warming temperatures, dry offshore
flow and increased fire concerns. 

&& of 03:00 AM PDT Thursday...Seasonably cool 
conditions are forecast over the region today as a mid/upper 
trough persists over the region. Afternoon temperatures will be 
cooler at the coast today compared to yesterday, generally ranging
from the upper 60s to lower 70s wile inland areas warm into the 
middle 60s to upper 70s. In addition, mostly sunny conditions are 
likely region-wide. 

High pressure building over the eastern Pacific will then begin to 
build toward the West Coast through the upcoming weekend. This will 
result in a warming trend through the weekend with more widespread 
80s across the interior by Friday and even lower 90s by Saturday 
afternoon. With the lack of a marine layer and persistent onshore 
flow, coastal areas will also warm into the 70s to even lower 80s 
through Saturday. 

Conditions trend slightly cooler on Sunday and Monday as a mid/upper 
level trough drops southward into the Pacific Northwest and 
Intermountain West. Mainly dry weather conditions are likely as this 
system will lack sufficient moisture and the best mid/upper level 
support stays inland to the east of the region. With the upper level 
low lingering over the Desert Southwest into early next week and a 
ridge of high pressure building inland to our north, weak offshore 
flow will potentially develop over the region. As a result, warming 
temperatures and much drier conditions are likely to develop by 
Tuesday and Wednesday of next week. Thus, the forecast will need to 
be closely monitored in the coming days as this pattern will create 
the potential for increased fire concerns. 


.AVIATION...As of 04:35 AM PDT Thursday...Well mixed out marine
layer and less observed vs model low level moisture keeping
predominately clear skies/VFR regionwide. Fog satellite imagery
does shows a few pockets of low clouds around the broader region
this morning which may spread and manifest into few clouds into
the sunrise hours. NW winds pick up across the coastal waters
today meaning locally breezy to gusty conditions by this afternoon
through coastal gaps including near KSFO where peak winds of 18kt
sust and gusts to 24kt are possible. For tonight, models keep
boundary layer relatively dry with mostly clear skies. 

Vicinity of KSFO...VFR. A few clouds may develop into sunrise
hours before mixing out by mid morning. Afternoon onshore winds
sustained 15-18kt with gusts 22-24kt possible. 

SFO Bridge Approach...Similar to KSFO.

Monterey Bay Terminals...Generally VFR. Sat imagery does show some
low cloud development near KWVI and meandering southward towards
KSNS. Winds mainly light except locally breezy with isolated weak
gusts in the Salinas valley this afternoon. 

&& of 04:28 AM PDT Thursday...Northwest winds increase
today across the waters. The strongest winds will be in the outer
waters north of Point Reyes and locally south of Point Sur along
the Big Sur coast. An 11 second northwest swell will be the
predominate wave in the waters today, bringing the potential of
hazardous conditions from squared seas to portion of the waters. A
much lighter southerly swell will also be mixed  in.


     .Tday...SCA...Mry Bay from 3 PM
             SCA...Pt Arena to Pt Reyes 0-10 nm from 3 PM
             SCA...Pigeon Pt to Pt Pinos 0-10 nm from 3 PM
             SCA...Pt Arena to Pigeon Pt 10-60 nm from 9 AM
             SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm
             SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm from 3 PM




Visit us at

Follow us on Facebook, Twitter, and YouTube at: