275 
FXUS66 KMTR 110525
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco Bay Area
1025 PM PDT Wed Oct 10 2018

.SYNOPSIS...Moist onshore flow will result in seasonably cool 
weather conditions into Thursday. Weak offshore flow will then 
develop late in the week resulting in warmer and drier conditions 
regionwide through the weekend if not into next week as well.

&&

.DISCUSSION...as of 9:20 PM PDT Wednesday...An upper level vort 
center moved through the area today mixing out the marine layer. 
Inland temperatures were 8 to 13 degrees cooler than yesterday and
better rh recoveries are being seen in the North and East Bay 
Hills. Low clouds have scattered out this afternoon and evening 
but should reform later tonight at a lower level as the marine 
layer becomes reorganized.

The vort max that passed through today will form into a cutoff low
over southern California on Thursday while upper level high builds
off the Pacific Northwest. A warming trend will begin Thursday and
continue through the weekend. Winds aloft will switch to the 
northeast so another round of offshore winds is expected in the
mountains. Winds Thursday night and Friday morning will be 
stronger with gusts up to 30-35 mph in Napa and eastern Sonoma
Counties and 20-25 mph in the other North Bay Mountains and East 
Bay Hills. Winds will decrease Friday night as the low moves away 
but may increase again Saturday night and Sunday morning as 
another inside slider drops into the Great Basin. Winds over the 
Santa Cruz Mountains and the Santa Lucias will also be offshore 
but wind speeds will be light. It looks like winds will not be 
strong enough nor will RH values be low enough for any wind or 
fire weather advisories. RH values will decrease towards the 
weekend as the persistent offshore flow dries out the airmass.

Inland temperatures are likely to warm back into the 80s Friday
through Sunday while 70s will be common near the coast. Low 
clouds will also be less widespread Thursday night through the 
weekend given the pattern in place. Medium range models show a rex
block keeping dry weather over the area for next week. 

&&

.AVIATION...as of 10:25 PM Wednesday...For 06z tafs. Stratus has
now become more widespread with MVFR to IFR cigs at KSTS, KMRY and
KSNS. IFR/MVFr cigs will continue into the morning between around
16z-18z. Still expecting KSJC and KLVK to remain VFR through the
period. Winds will remain light overnight before increasing and
turning onshore tomorrow afternoon.

Vicinity of KSFO...VFR prevailing. Brief MVFR cigs possible 
around sunrise tomorrow morning. Light winds overnight turning 
onshore and increasing to around 15 kt tomorrow afternoon.

SFO Bridge Approach...Similar to KSFO.

Monterey Bay Terminals...Currently MVFR. Expecting cigs to lower
to become borderline IFR overnight. Clearing currently forecast 
between 17z-18z. 

&&

.BEACHES...Tropical storm Sergio will bring moderate period and
height swell to the Central California and Bay Area coastlines
beginning Thursday morning. Exposed south facing beaches will be
at highest risk for building surf. Some breakers may reach as high
as 10 feet with 10 to 20 minute lulls between sets. All beaches
will experience an increase in rip current activity during the
second half of the week as this swell arrives and transits the
area. Therefore, a Beach Hazards Statement has been issued from
early Thursday morning through late Friday afternoon.

&&

.MARINE...as of 08:14 PM PDT Wednesday...Split flow will continue
with lighter southerly winds along the coast and more gusty 
northwesterly winds over the northern outer waters. Winds overall 
will diminish across the coastal waters throughout the day 
tomorrow and remain generally light heading into the weekend. 
Mixed northwest and southerly swell will persist through the 
forecast period. The southerly swell generated by Tropical Storm 
Sergio will increase tomorrow and Friday before subsiding in the 
late afternoon.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .Tngt...SCA...Pt Arena to Pigeon Pt 10-60 nm until 3 AM

&&

$$

PUBLIC FORECAST: W Pi
AVIATION: AS
MARINE: AS

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