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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS66 KMTR 191740
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco Bay Area
1023 AM PDT Thu Apr 19 2018

.SYNOPSIS...A warming trend and dry weather conditions are by
Friday and through the upcoming weekend. A weak cutoff low
approaches the region mid to late next week.

&&

.DISCUSSION...as of 09:00 AM PDT Thursday... Another cool morning
in the wake of a cold frontal passage with temperatures observed around
5 to 10 degrees lower versus 24 hours ago. The upper low
responsible for these cooler temperatures is exiting into the
Great Basin this morning. Only a handful of sites reported any
precipitation from this storm system after it juked southward into
Big Sur country just as it approached the Monterey Bay region.
Fort Hunter Liggett in southern Monterey county picked up .10" to
lead the way while most locations didn`t get a drop.

For today, breezy to locally gusty northwest winds will prevail,
especially along the coast, with slightly to somewhat warmer
temperatures compared to yesterday. Mostly clear skies are
expected with some weak cumulus development possible in the
afternoon.

Fair weather conditions are expected through the weekend and into
early next week. A slight warming trend is forecast now through
the weekend where temperatures will rise to a few degrees above
normal at the coast (mid to upper 60s) and up to 10 degrees warmer
than normal farther inland (upper 70s to low 80s). A weak upper
trough passes to the north later in the weekend that stems the
warming trend over the San Francisco Bay area, but should not
mitigate the warming trend for the Monterey Bay area. Temperatures
will increase slightly again on Monday.

GFS and Euro show a cutoff low approaching the region midweek next
week, however, the GFS has it much closer to the CONUS while the
EURO keeps it well offshore. Both models agree that the upper low
eventually approaches California by late next week, skirting along
the NorCal coast before pushing inland over SoCal. Can not rule
out light rainfall from this storm at this point but given current
data, it will be fairly light and mainly focused over the
southern counties. Stay tuned as the story of this storm system
comes into view. Finally, the 384 hr GFS shows mainly benign
weather for the region, so we may be at the end of the rainy
season. Now, who`s ready for stratus season?

.PREVIOUS DISCUSSION...as of 3:17 AM PDT Thursday...The system
moving south along the coast is rapidly weakening as it moves
south. So far the only bucket tips have been in Big Sur with a few
stations reporting 0.04 of an inch over the past several hours.
Temperatures are also cold in the Santa Lucias...28 degrees at
Chews Ridge...so there could be a few snow flurries at higher
elevations in Big Sur for the next couple of hours. Precipitation
will end this morning as the system moves south.

Dry conditions with slightly warmer temperatures are expected
today. High pressure building over the eastern Pacific by Friday
will bring warmer temperatures through the weekend. Highs over the
weekend are forecast to reach into the mid 80s across inland
areas by Sunday. Mild conditions to persist into next week.

Medium range models are still indicating a closed low moving into
California by the middle of next week. The location and track of
this low vary by model, so confidence is very low concerning one
solution over another. There could possibly be one more shot of
rain for the area, but right now it is not looking highly likely.

&&

.AVIATION...As of 10:22 AM PDT Thursday...For 18z tafs. Visible
satellite shows patchy low cigs affecting the Monterey
Peninsula/Northern Salinas Valley region. Difficult to say if
these low clouds will persist and/or lift through the afternoon.
Amendments to the KMRY & KSNS TAFs may be necessary as the day
progresses. Elsewhere, VFR is expected through the afternoon, with
breezy and occasionally gusty onshore winds by early afternoon.
There remains some questions whether cigs return this evening.
Kept cigs out of the TAF for SF Bay Area terminals for now, but
did include cigs tonight for Monterey Bay terminals, with low
confidence on coverage and timing.

Overall forecast confidence: Moderate

Vicinity of KSFO...VFR will prevail through the afternoon and
early evening. Afternoon west winds to around 20 kt, with gusts
over 25 knots possible.

SFO Bridge Approach...Similar to KSFO.

Monterey Bay Terminals...Low level clouds affecting KMRY, but
should lift above 3000 feet by noon or so. Will amend TAF if
necessary. Light to moderate westerly winds this afternoon, 10-15
kt.

&&

.MARINE...as of 9:01 AM PDT Thursday...Breezy NW winds will
prevail today into Friday and will produce steep wind waves,
making for rough seas. Winds will remain moderate to strong
through the weekend as high pressure builds and surface gradients
tighten near Cape Mendocino.

&&

.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: DRP
AVIATION: BAM
MARINE: BAM

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