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)

                            
000
FXUS66 KMTR 211818
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco Bay Area
1118 AM PDT Sun Apr 21 2019

.SYNOPSIS...High pressure will begin to build over the region on 
Sunday resulting dry weather conditions and slightly warmer 
temperatures. A more noticeable warming trend will develop early 
next week and extend through midweek with temperatures well above 
seasonal averages. 

&&

.DISCUSSION...as of 09:11 AM PDT Sunday...Cloud cover quickly
dissipating over inland areas this morning as high pressure begins
to take control of the region. Looking for mostly sunny conditions
this afternoon with temperatures warmer than yesterday, generally
near seasonal averages. With this, the ongoing forecast remains 
on track with no updates anticipated this morning. For full 
details, please see the previous forecast discussion below.

&&

.PREV DISCUSSION...as of 02:10 AM PDT Sunday...Overnight satellite 
imagery shows a fractured marine layer over portions of the Bay 
Area as an upper level trough exits to east and high pressure 
begins to build overhead. Persistent stratus deck continues to 
cling to the Monterey Bay region with low clouds extending up the 
San Mateo Coast and over the East Bay Hills. Profiler puts the 
depth at 2,000 feet or greater. Monterey airport is even reporting 
-RA, similar to yesterday. Therefore, low clouds, patchy fog and 
drizzle will remain in the forecast through this morning. On the 
flipside, San Francisco and locations northward remain mostly 
clear. One other interesting tidbit this morning are the 
temperatures above 4,000 feet. Chews Ridge located above Big Sur 
is currently sitting in the low 30s, rather impressive for late 
April.

The weather story for the day will be building high pressure. High
pressure building over the region today kicking off a warming 
trend through midweek. Do expect the morning clouds to erode by 
mid to late morning yielding mostly sunny skies this afternoon. 
Unlike Saturday where coastal areas struggled to reach 60 
temperatures should warm into the mid 60s for most locations. 
Interior locations will warm as well with highs into the mid 70s. 
The building high pressure will also lead to a period of breezy to
gusty offshore flow Monday and Tuesday. Not much in the way of 
any marine layer due to the NE winds. NE winds will not only help 
warm daytime temperatures, but overnight lows in the hills will 
remain mild as well. Models have been rather persistent with 
Tuesday and Wednesday being the warmest with 60s and 70s at the 
coast and widespread 80s to possibly low 90s across the interior.
Enough cooling will occur overnight to limit heat risk impacts, 
but persons with outdoor activities on Tuesday/Wednesday should 
take some precautions given the forecasted warmth. 

The ridge flattens on Thursday as an upper level trough approaches
from the northwest. Temperatures will moderate on Thursday.
Temperatures will cool even more on Friday and into next weekend -
closer to seasonal levels. Previous model runs hinted at precip
next weekend and then backed off. The latest 00Z run of the
Canadian and ECMWF now show an upper low undercutting the ridge
bringing some precip to the region. The GFS is more zonal and dry.
Forecast will remain dry at this point, but something to watch
between now and then.

&&

.AVIATION...As of 11:15 AM PDT Sunday...Predominately VFR through
the day, localized IFR/MVFR overnight into Monday morning along
the coast. A few low to mid level clouds will linger through the 
morning but dissipate into the afternoon. Breezy to locally gusty 
onshore winds again today, though weaker than yesterday. 

Vicinity of KSFO...VFR. Breezy to occasionally gusty onshore 
winds this afternoon. SCT clouds 1000-1500 ft possible late
overnight into Monday morning.

SFO Bridge Approach...Similar to KSFO.

Monterey Bay Terminals...VFR through the afternoon. Marine layer
return expected later into the evening and overnight. Some models
bringing a little bit of drizzle to the coast with the marine
layer early Monday morning (prior and up to sunrise). Breezy
onshore winds this afternoon.

&&

.MARINE...as of 11:14 AM PDT Sunday...Gusty northwest winds across
the waters today. Occasional gale force gusts are possible through
tonight. These gusty winds will generate steep fresh swell that is
hazardous for small craft vessels. Northwest winds dissipate
somewhat into midweek. Northwest seas.

&&

.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
             SCA...Pt Arena to Pigeon Pt 10-60 nm
             SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm
             SCA...Mry Bay

&&

$$

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

Visit us at www.weather.gov/sanfrancisco

Follow us on Facebook, Twitter, and YouTube at:
www.facebook.com/nwsbayarea
www.twitter.com/nwsbayarea
www.youtube.com/nwsbayarea