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Area Forecast Discussion (AFD)

Issued by San Francisco Bay Area, CA (MTR)

FXUS66 KMTR 170552

Area Forecast Discussion
National Weather Service San Francisco Bay Area
1052 PM PDT Tue Apr 16 2019

.SYNOPSIS...A warming trend is forecast for Wednesday and 
Thursday. Temperatures are expected to climb well above normal by
Thursday, with widespread 80s for inland locations and 70s near
the coast. A cooling trend is forecast to begin on Friday and 
continue into the weekend. Dry conditions are forecast through 
the weekend and well into next week.


.DISCUSSION...As of 8:40 PM PDT Tuesday...Scattered cumulus 
clouds dissipated early this evening and skies are now mostly 
clear across our region. Skies are expected to remain mostly clear
overnight, although patchy low clouds may begin to develop near 
the coast late tonight as the low levels become more stable. 

An upper level ridge, currently centered offshore along 130W, is
forecast to shift eastward and over California by late Wednesday,
and reach its maximum strength over our area by midday Thursday.
The warming trend that will result will be most notable across
inland areas on Wednesday when high temperatures will be as much
as ten degrees warmer than today. Light onshore flow on Wednesday
will limit coastal warming to 5 degrees or less. Patchy coastal
low clouds may become a bit more widespread by Wednesday evening
as a shallow marine layer becomes established. However, light
offshore flow is forecast to develop by Thursday morning, which
will keep any low clouds/fog confined to the immediate coast
Wednesday night, and result in mostly sunny coastal conditions by
midday Thursday. Thursday will be the warmest day of the week, 
when inland areas will see widespread highs in the 80s, while 
coastal areas warm into the 70s. Many locations will likely post 
their warmest temperatures so far this year on Thursday, but 
record highs are not anticipated.

The upper ridge is forecast to shift to our east and weaken by
Friday, and onshore flow will redevelop and increase by 
afternoon. Coastal areas will cool by as much as 10 to 15 degrees 
on Friday. Also, expect increasing low clouds in coastal areas 
during the day. Inland cooling on Friday will be less significant,
probably on the order of about five degrees. Cooling will 
continue on into Saturday, especially inland, as an upper trough 
sweeps across northern California. Models forecast scattered 
shower activity with the trough on Friday night and Saturday, but 
confine precipitation to the higher mountains to our north and 
east. Thus, it's likely that dry conditions will prevail across 
our region through the weekend.

Temperatures are expected to begin to rebound on Sunday and then
continue to warm into the early part of next week as upper level
ridging develops over California once again.

&& of 10:45 PM PDT Tuesday...VFR conditions prevail 
at all terminals, but current fog product satellite imagery shows
areas of stratus starting to form along the coast south of the 
Golden Gate. Key forecast question remains ceiling development 
during overnight and early morning hours. Mixed signals from 
models and statistical guidance. Upshot though is that it appears 
likely for the Monterey Bay terminals and unlikely for those in 
the San Francisco Bay Region.

Vicinity of KSFO...Onshore winds will continue to diminish
overnight becoming light and variable during the morning 
hours. Latest model output indicates diminished chances of late 
night/early morning ceiling development so am maintaining VFR 
conditions throughout the forecast period, but confidence is on 
the low side.

SFO Bridge Approach...Similar to KSFO.

Monterey Bay Terminals...MVFR ceilings projected to develop over
the next few hours and then continue well into the morning before
clearing. Light winds turning onshore 10 to 15 kt Wednesday
afternoon. Moderate confidence.

&& of 09:15 PM PDT Tuesday...Moderately strong and gusty
northwest winds over the waters will diminish a bit later tonight
and Wednesday. However, gusty winds will remain possible along 
the coast and just offshore Wednesday afternoon and evening. A 
moderate northwest swell will continue through the forecast 


     .Tngt...SCA...Mry Bay until 11 PM
             SCA...Pt Reyes to Pigeon Pt 0-10 nm until 11 PM
             SCA...Pigeon Pt to Pt Pinos 0-10 nm until 11 PM
             SCA...Pt Arena to Pt Reyes 0-10 nm until 3 AM
             SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm until 3 AM
             SCA...Pt Arena to Pigeon Pt 10-60 nm until 3 AM
             SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm until 3 AM




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