150
FXUS66 KMTR 030049
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
549 PM PDT Thu May 2 2024

...New AVIATION, MARINE...

.SYNOPSIS...
Issued at 119 PM PDT Thu May 2 2024

Warm weather continues through the day today and tomorrow
afternoon. Beneficial rain befalls the region late Friday and
through the afternoon of Saturday. Cool overnight temperatures
expected Sunday and Monday mornings. Dry conditions return Sunday
and last through next week.

&&

.SHORT TERM...
(This evening through Friday)
Issued at 119 PM PDT Thu May 2 2024

A look across the region at this hour shows many interior locations
already reaching into the low to mid 70s. Meanwhile closer to the
coast and bay shorelines, temperatures are in the upper 50s to low
60s. Temperatures will warm today into the high 70s away from the
coastline, with a select few locations maybe seeing temperatures
reach the 80 degree F mark. However, chances of reaching the 80
degree mark are fairly low even for the favored interior spots. Napa
appears to be the most highly favored for the chance to reach 80
degrees, but even then, with only a whopping 30% chance. Elsewhere
in locations such as Gilroy and Hollister, chances are only in the
20% range. Coastal locations will only see highs in the mid 60s at
best.

As upper level ridging builds and continues, temperatures are
expected to be largely similar tomorrow. Breezy northwesterly winds
in the afternoons will continue, but ease into the nighttime.

Late Friday night, rain begins to approach the region, impacting the
North Bay first, and then slowly making its way south. The previous
forecaster`s long term discussion still largely holds, so will
not reinvent the wheel. Will just mention that rain totals have
increased ever so slightly from the previous forecast, but not by
much. By a few hundredths generally. Descriptions in the long term
discussion still hold largely.

&&

.LONG TERM...
(Friday night through next Wednesday)
Issued at 119 PM PDT Thu May 2 2024

Seeing good global and mesoscale model agreement, one long wave
trough is now stationary along the West Coast, part of an unsteady
northern hemispheric long wave trough pattern. A low pressure
system from the Aleutian Islands will move through the long wave
trough and bring rain to our forecast area Friday night and
Saturday. Rain developing first over the North Bay Friday night,
rain quickly spreading southeastward across much of the rest of
the forecast area Saturday. Expect noticeably cooler temperatures
especially inland Saturday with daytime highs in the upper 50s to
mid 60s, warmest southern interior; daytime temperatures 5F to 15F
below early May normals. The low is still expected to brush by
and tap higher levels of water vapor extending far north of
Hawaii, while retaining a strong mid-latitude influence e.g. it`s
an appreciably cold core system up through the 700 mb level by
comparison on Oakland upper air climatology, the pool of cold air
a little more compact by the 500 mb level. Unlikely there`ll be
layer instability extending above 700 mb, forecast 700-500 mb
lapse rates are low and much more stable. Recent precipitable
water values on the GFS maintain between 1.00" and 1.10" Saturday,
not far from the max moving average on Oakland upper air sounding
climatology in early May.

Seeing some recent increases in model forecast rainfall amounts.
For example over 0.50" to 1" rain totals North Bay, near 0.50" low
elevations and up to 0.75" to 1" East Bay hills/mountains and the
Santa Cruz Mountains, 0.10" to 0.20" interior north Central Coast to
around 0.50" Big Sur Coast. The Bay Area and northernmost north
Central Coast may receive over half if not nearly May normal
precipitation from this system if current QPF verifies. As mentioned
expect wet and cooler weather Saturday, gusty northwest winds over
the coast temporarily subsiding with the passage of a surface cold
front/trough.

Chilly to cold overnight low temperatures for the time of year (40s
coastside and bayside / 30s inland) are forecast late Saturday night
to Sunday morning and Sunday night to Monday morning. San Francisco
and Oakland downtown possibly including a few other locations may be
nearing record lows Sunday and Monday mornings. Stay tuned to updates,
right now Sun-Mon mornings look to be the chilliest. Forecast temperature
guidance could edge a little lower between now and late weekend.

End of previous discussion.

Overall, this weekend`s system will bring beneficial, although
late-season rain. Late Saturday, rain begins to cease and a dry
pattern returns to the region with temperatures gradually warming
through the next week into the low to mid 70s for interior regions.
Despite gradual warming, CPC 6-10 day outlooks place much of
California in a below-normal temperature category, and below
normal for precipitation.

&&

.AVIATION...
(00Z TAFS)
Issued at 548 PM PDT Thu May 2 2024

VFR remains through the night and much of Friday for all but the
immediate coast and MRY. Breezy and gusty winds continue into the
early night. Winds ease into the late night becoming light to
moderate. As winds reduce MVFR/IFR CIGs build along the coast and
Monterey Bay. Cloud cover thins in the mid to late morning Friday.
Gusty westerly winds arrive Friday afternoon and last into the
night. As winds reduce, low clouds move into the coast and bays
Friday night, leading to MVFR and IFR CIGs.

Vicinity of SFO...VFR through the TAF period. Gusty northwest winds
with around 35-40 kt kt gusts last into the night before dropping
off. Scattered lower clouds arrive in the late night and last into
mid Friday morning. Gusty west winds build into Friday afternoon,
peaking around 27 kts and gusting to above 30 kts. Winds reduce into
late Friday evening, but remain breezy.


SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...MVFR/IFR CIGS affect MRY and the immediate
coast of the Monterey Bay through the mid to late morning. Breezy
winds last into the late evening before reducing. Winds stay light
to moderate through the night before moderate to breezy winds arrive
Friday afternoon.
&&

.MARINE...
(Tonight through next Wednesday)
Issued at 548 PM PDT Thu May 2 2024

Strong winds persist throughout Friday afternoon, with gale force
gusts of 35 to 45 knots possible. Strong winds will result in
hazardous seas and steep wind waves with significant wave heights
reaching 10 to 13 feet in the outer waters. Conditions briefly
improve over the weekend, but will increase into next week to more
moderate levels. Rain chances begin late Friday night as a trough
descends over the region into Saturday.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Gale Warning until 9 PM PDT this evening for Mry Bay-Pigeon Pt
     to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 0-10 nm-Pt Arena
     to Pt Reyes 10-60 NM-Pt Reyes to Pigeon Pt 0-10 nm.

     Gale Warning until 3 AM PDT Friday for Pigeon Pt to Pt Pinos 0-
     10 nm.

     Gale Warning until 3 AM PDT Saturday for Pt Pinos to Pt Piedras
     Blancas 0-10 nm.

&&

$$

SHORT TERM...AC
LONG TERM....Canepa
AVIATION...Murdock
MARINE...RGass

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