FXUS66 KMTR 090531
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco Bay Area
1031 PM PDT Sat Aug 8 2020

.SYNOPSIS...Warmer temperatures are expected to continue through
the remainder of the weekend, especially inland. Slightly cooler 
weather returns early next week.

&&

.DISCUSSION...As of 8:50 PM PDT Saturday...Current synoptic
pattern consists of a broad upper ridge extending from the Eastern
Pacific to the Southern Plains, with the ridge bisected by a weak
upper low near the Central California Coast. Easterly flow to the
north of this weak upper low has brought high clouds over the Bay
Area this evening. These clouds are remnants of afternoon 
thunderstorms over the Sierra. Otherwise, the ridge is our 
dominant weather feature, and will continue to be so through the 
remainder of the weekend, producing slightly warmer than normal 
temperatures across most inland areas, while the coast remains 
seasonably cool due to onshore flow and a persistent marine layer.

Temperatures today were slightly warmer across most inland areas 
compared to Friday, except in the North Bay Valleys where low 
level southerly flow resulted in cooling by a few degrees. The 
weak upper low to our south is forecast to drift westward through 
Sunday, which should allow the ridge to strengthen slightly over 
our area and decrease the depth of the marine layer by at least a 
few hundred feet. Therefore, inland temps should warm a few 
additional degrees on Sunday.

A low amplitude upper trough is forecast to settle into the
Pacific Northwest by late Monday. This will weaken the ridge 
enough to result in modest cooling across our area on Monday and 
Tuesday, with inland temps expected to retreat back to near normal
by Tuesday and Wednesday. Also, expect an increase in the marine 
layer depth early in the week, which will mean more widespread 
night and morning low clouds.

Forecast confidence falls off in the longer range due to model
disagreement. The ECMWF forecasts the ridge over the Desert
Southwest to build westward over California late next week and
into the following weekend, resulting in a warming trend,
especially for inland areas. The GFS is slower and weaker in
building the ridge and thus keeps temperatures near seasonal
averages. One item to watch in the longer range forecast is
moisture from a tropical system currently developing off the 
west coast of Mexico. Models show some of this tropical moisture 
rotating around the upper high and across south-central California
by late next week. 

&&

.AVIATION....As of 10:31 PM PDT Saturday...for 00z TAFs. VFR with
high clouds moving over the SF Bay from storms out east. The 
marine layer's impacts will be limited as higher pressure builds. 
Clouds will remain mainly near the coast for MVFR, isolated IFR, 
and clearer inland. Earlier clearing Sunday for VFR. Winds remain 
onshore and will lighten overnight before becoming breezy Sunday 
afternoon. Stratus will return to terminals Sunday evening, but 
not expected to be widespread around the region.

Vicinity of KSFO...VFR. High clouds move over the terminal from 
storms over the Sierra Nevada, while stratus is slowly moving in 
through the Golden Gate. Winds remain onshore and breezy, and will
reduce overnight. Limited coverage expected overnight, but a 
small chance for brief IFR conditions early Sunday morning 
(similar to Saturday morning). Clouds will mix out after 16z for 
VFR Sunday afternoon with breezy winds once again. Winds will 
again be northeasterly in the late morning/early afternoon before 
switching back to onshore.

SFO Bridge Approach...Similar to KSFO.

Monterey Bay Terminals...IFR. Winds have become light, and at
times calm. Clouds have finally moved over the terminals and cigs
will continue to lower with LIFR conditions possible early Sunday
morning. Clouds are expected to begin to lift after 16z for VFR
Sunday afternoon, with traditional breezy onshore winds. Stratus
is expected to return to the Peninsula after 04z Sunday evening.

&&

.MARINE...as of 8:32 PM PDT Saturday...Winds over the northern 
outer waters continue to be out of the northwest and gusty, while 
lighter southerly winds are along the immediate coastline. Sunday 
will bring breezier winds through the Golden Gate and into the 
northern San Francisco Bay toward the Delta on Thursday. These 
winds will generate steep fresh swells resulting in locally 
hazardous seas, especially for smaller vessels. Mixed seas will 
continue through the period with a short period northwest swell 
and a longer period southerly swell.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .Tngt...SCA...Pt Arena to Pigeon Pt 10-60 nm

&&

$$

PUBLIC FORECAST: Dykema
AVIATION: DK
MARINE: DK

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