049
FXUS66 KMTR 110624
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
1124 PM PDT Fri May 10 2024

...New AVIATION, MARINE...

.SYNOPSIS...
Issued at 125 PM PDT Fri May 10 2024

Warm temperatures continue inland through Saturday with highs from
the upper 80s to lower 90s. Cooling has begun at the coast and
spreads inland over the weekend into Monday with seasonal to warm
temperatures through the next week.

&&

.UPDATE...
Issued at 832 PM PDT Fri May 10 2024

Low clouds can be seen on satellite imagery over the Monterey Bay
region and are expanding inland at this hour. Also, they are working
there way up the San Franciso Peninsula and spreading inland around
Santa Cruz. The latest HRRR has them spreading inland overnight up
and down our entire coastline, through the Golden Gate and locally
into the Salinas Valley. This may be a bit overdone, but the general
trend is for them to expand in coverage first over the ocean and
then inland. Overall, the forecast remains on track with no updates
anticipated at this time.

&&

.SHORT TERM...
(This evening through Saturday)
Issued at 125 PM PDT Fri May 10 2024

A larger scale ridge is starting to weaken as it comes into the
Pacific Northwest, diminishing the offshore flow that contributed to
the warm coastal temperatures the last two days. Satellite imagery
shows stratus decks along the Big Sur coast, flowing into
Monterey Bay and the coast of the San Mateo Peninsula. While this
definitely looks like a southerly surge, observed coastal winds
are more westerly than southerly, helping to cool off the coastal
regions as the breezes develop through the day. Downtown San
Francisco, which hit a high of 81 yesterday, is forecast to top
out at 76 today. Elsewhere, the Pacific coast should expect highs
around the low to mid 60s while the Bayshore could see highs reach
the low 80s today. Further cooling is expected on Saturday with
the coast seeing highs around 60 and the Bayshore seeing highs in
the mid to upper 70s.

Without the moderating impact of the onshore sea breeze, and with
the ridge axis moving into the state, interior regions remain warm.
The highs today will range from the upper 80s to lower 90s across
the interior valleys with similar highs expected to continue into
tomorrow. A Minor HeatRisk throughout the inland area, and a
Moderate HeatRisk for the interior North Bay, East Bay, and South
Bay will continue into Saturday; this means that a low to moderate
risk of heat-related illnesses continues for vulnerable populations.

The higher elevations should see highs in the 70s with a few degrees
of cooling on Saturday. Low temperatures throughout the region on
Saturday morning will hover in the low to mid 50s in the lower
elevations, and the upper 50s to low 60s in the mountains.

Given the continuing warm temperatures inland, here`s a reminder of
some heat safety tips:

* Stay hydrated and drink plenty of fluids.
* Wear lightweight, light-colored clothing.
* Reduce time spent outdoors or stay in the shade.
* Never leave people or pets unattended in vehicles.
* Use sunscreen if going to the coast or the pool.

Satellite imagery is also showing some pop-up clouds over the area
near San Bruno Mountain. The HREF and NAM are suggesting some chance
of showers over the extreme south of San Bruno County and southeast
of Monterey County through the afternoon. The HRRR isn`t showing any
rainfall developing in the area. The forecast shows a slight chance
of showers in the area, which was carried forward from overnight. If
showers do develop, any rainfall totals will be very light with
around a few hundredths of an inch at most.

&&

.LONG TERM...
(Saturday night through next Thursday)
Issued at 125 PM PDT Fri May 10 2024

The weakening ridge will allow for a cooling and moistening trend to
start for the interior regions and continue in the coastal regions
on Sunday into Monday, with slight fluctuations in the temperature
expected through the upcoming work week. Coastal locations will rise
to the low to mid 60s through the end of the next week, with the
inland valleys hovering around the low to mid 80s for the most part,
perhaps up to the upper 80s in the warmest spots. Tuesday, in
particular, should see an uptick in the temperatures as a second
ridge comes into the Pacific Northwest, combining with a weak upper
level low tracking into southern California to bring some
northeasterly flow to the region. Atmospheric moisture does begin to
develop through the region towards the middle and end of next week,
although the highest chances for precipitation appear to lie near
the Sierras.

Ensemble clusters are hinting at a possible trough coming through
the western United States around the end of next week or the
upcoming weekend. The CPC`s 8-14 day outlook suggests that
temperature and precipitation for the period between the 18th and
the 24th will be around the seasonal averages.

&&

.AVIATION...
(06Z TAFS)
Issued at 1121 PM PDT Fri May 10 2024

Currently VFR at all terminals with the exception of
LIFR at MRY. VFR through the TAF period at all terminals with the
exception of MRY and SNS; however, that being said the current
situation at MRY is significantly overperforming compared to models
and guidance. The compressed marine layer will continue to favor the
coastal locations of MRY and SNS. Confidence is much lower on if OAK
and/or SFO will experience stratus as it will have to be able to
make it through the Golden Gate Bridge. Because the marine layer is
shallower than 1,000 feet, it is unlikely that stratus will be able
to make it through the San Bruno Gap to impact SFO. If stratus were
to develop at either OAK or SFO overnight, it will likely be IFR if
not LIFR with timing looking to be somewhere between 10Z and 16Z.
Widespread VFR and breezy onshore flow will prevail by tomorrow
afternoon.

Vicinity of SFO...Currently VFR with breezy northwesterly flow. Low
confidence that stratus will develop at the terminal overnight,
but models do show some creeping of stratus into the Bay with a
potential for temporary stratus sometime between 10Z and 16Z.
Winds will remain breezy out of the northwest overnight and be on
the increase tomorrow afternoon. Winds turn to a more westerly
component by tomorrow night.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Currently LIFR and calm at MRY and VFR with
breezy northwesterly flow at SNS. SNS is expected to deteriorate
quickly as LIFR stratus is within the 5 mile radius of the terminal
and continuing to slowly expand. Once SNS drops, both terminals are
likely to remain LIFR until late morning tomorrow. Winds will remain
light and variable overnight before becoming breezy out of the
northwest by tomorrow afternoon.

&&

.MARINE...
(Tonight through next Thursday)
Issued at 1121 PM PDT Fri May 10 2024

Light to moderate west to northwest winds over the coastal waters
will continue through Saturday. By the beginning of the work
week, high pressure will build and bring building significant wave
heights, continued dry weather, and northwesterly winds will
strengthen from light to moderate to a fresh breeze.

&&

.BEACHES...
Issued at 719 PM PDT Fri May 10 2024

Long period southwest swell will lead to slightly elevated chances
for sneaker wave and rip current development this weekend.
Conditions are expected to stay below Beach Hazards Statement
criteria as swell height will only be between 1-2 feet. However, in
light of anomalously warm temperatures and increased likelihood of
people traveling to the coast, visitors to the beach should remember
to take safety precautions to prevent being caught by an unexpected
large wave and to never turn your back on the ocean.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...None.
&&

$$

SHORT TERM...DialH
LONG TERM....DialH
AVIATION...Sarment/Kennedy
MARINE...Kennedy

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