-- Discussion containing changed information from previous version are highlighted. --
299
FXUS66 KMTR 040408
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
908 PM PDT Fri May 3 2024

...New UPDATE, MARINE...

.SYNOPSIS...
Issued at 1237 PM PDT Fri May 3 2024

Cold front on track to bring widespread rain, cooler temperatures,
and gusty winds this weekend. Dry weather returns Sunday with a
gradual warming trend through next week.

&&

.UPDATE...
-- Changed Discussion --
Issued at 907 PM PDT Fri May 3 2024

The forecast for the incoming low pressure system remains largely on
track with minimal changes. HRRR guidance shows the low slowing down
slightly with rain arrival times pushes back by an hour or two. Rain
will arrive during the early to late morning hours moving north to
south. Based on HRRR guidance, the most likely arrival times are 3AM-
5AM for the North Bay, 7AM-10AM for the East Bay and South Bay, and
8AM-11AM for the Central Coast. Rainfall totals look largely the
same with between 0.5-1.0 inches expected in the Bay Area and 0.2-
0.5 inches expected in portions of the Central Coast. Locally higher
precipitation totals are expected in the coastal North Bay mountains
and the Santa Cruz mountains. Gusty winds will extend inland from
the coast as the system passes with gusts between 25-30 mph
possible. Trend for below average daytime and overnight temperatures
tomorrow through the early work week remains on track.
-- End Changed Discussion --

&&

.SHORT TERM...
(This evening through Saturday)
Issued at 1237 PM PDT Fri May 3 2024

Mostly clear skies over the region today ahead of the next cold
front. Ample cloud cover associated with the front now moving into
the northern portions of the state will continue to move southward
through tonight. Areas of light rainfall are expected to begin
early Saturday morning along favored west-facing upslope areas
in the coastal ranges as moist low-level westerly flow increases
ahead of the front. Much of the surface front should be through
the Bay Area by mid-morning, and late morning for areas further
south along the Central Coast. Aided by a robust 150 kt NW-SE
oriented jet on the back side of the low, this will be a rather
quick-moving front with little-to-no chance of stalling. However,
this jet and continued support of an enhanced northwesterly Eastern
Pacific jet along the West Coast will support gusty northwest
winds to 25-35 mph along coastal areas and NW-SE oriented valleys
through the weekend. Rainfall amounts Saturday will be in the ball
park of 0.4-0.75" for most locations, with a few seeing upwards of
1-1.25" in the coastal ranges of the North Bay and the Santa Cruz
Mtns.

Behind the cold front Saturday afternoon and evening, there is a
slight chance for isolated thunderstorms across the area.
Scattered showers will persist into Saturday evening, but
conditions appear favorable for a few locally strong updrafts that
would support a rumble of thunder or two, as well as small hail.
Deep convection would not be supported, given limited cooling
aloft, promoting a more stable environment aloft. Thus, any storms
that do develop would be relatively short-lived. Really nothing
out of the ordinary for us during these typical cold core systems,
just more resemblant of a system we`d see in January rather than
May.

&&

.LONG TERM...
(Sunday through next Thursday)
Issued at 1237 PM PDT Fri May 3 2024

Sunday looks to be on the drier side with the low departing.
Temperatures the next few days will be on the cool side with
afternoon high temps dropping by as much as 18 degrees for inland
locations. Low temps Sunday morning will be in the 40s for most,
with a few pockets of upper 30s for inland and high elevation
areas. Otherwise, a warm up is on tap for the rest of next week as
the pattern becomes more ridge-dominant. By Wednesday, expect
afternoon highs in the 70s to near 80, and the mid-to-upper 60s
along the coast.

&&

.AVIATION...
(18Z TAFS)
Issued at 1126 AM PDT Fri May 3 2024

VFR lasts until the early to mid evening for most terminals before
IFR/LIFR level clouds move inland. Winds stay W/NW and remain
gusty through the evening. As stratus approaches in the evening,
winds become light to moderate, and slowly turn to become more
S/SW ahead of the approaching low pressure system. By the mid
morning hours of Saturday, most terminals will see winds increase
once more to become breezy and gusty out of the SW, and rain
begins, lowering visibilities at terminals. Cloud decks are
expected to improve to become IFR/MVFR as the rain approaches.
Rain continues into Saturday afternoon before dissipating, with
winds turning to become N/NW and breezy.

Vicinity of SFO...VFR conditions last through the evening, with
strong wings gusting to around 35 knots expected. Stratus makes
moves inland in the late evening, bringing IFR conditions as winds
reduce. Winds reduce further into the night and turn
southwesterly. These winds become gusty as the rain arrives early
Saturday morning with MVFR CIGs and slight reductions in
visibilty.Winds turn to become W/NW in the later morning, but
rain lasts through the afternoon.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...IFR/LIFR CIGs push inland in the early
evening. IFR/LIFR CIGs last through the majority of the overnight
hours with lighter winds. As the rain band arrives, expect CIGs
lift to become IFR/MVFR late Saturday morning. Gusty westerly
winds build along the rain band.

&&

.MARINE...
-- Changed Discussion --
(Tonight through next Thursday)
Issued at 907 PM PDT Fri May 3 2024

Expect breezy to gusty northwest winds to continue with gale
force gusts possible over the southernmost zones. This evening, a
low pressure system and associated cold front will arrive from the
north, bringing rain and moderate to fresh breezes across the
waters. Winds will turn briefly southwesterly ahead of the system
early Saturday morning, but turn to become northwesterly once more
in the late part of Saturday morning. Rain ceases late in the day
Saturday, and winds ease to become moderate into the new
workweek.
-- End Changed Discussion --

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
CA...None.
PZ...Small Craft Advisory from 9 AM to 9 PM PDT Saturday for Pigeon
     Pt to Pt Pinos 0-10 nm.

     Gale Warning until 9 AM PDT Saturday for Pt Pinos to Pt Piedras
     Blancas 0-10 nm.

     Small Craft Advisory from 3 AM to 9 AM PDT Saturday for Pt Arena
     to Pt Reyes 10-60 NM.
-- End Changed Discussion --

&&

$$

UPDATE...Kennedy
SHORT TERM...Behringer
LONG TERM....Behringer
AVIATION...Murdock
MARINE...Murdock

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