996
FXUS66 KMTR 092008
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
108 PM PDT Thu May 9 2024

...New SYNOPSIS, SHORT TERM, LONG TERM...

.SYNOPSIS...
Issued at 108 PM PDT Thu May 9 2024

Temperatures peak today along the coast with a incoming southerly
surge cooling the coastal regions on Friday. Interior regions see
temperatures peak on Friday, before a slight cooldown begins over
the weekend. Coastal regions cool to around the seasonal average
temperatures by early next week.

&&

.SHORT TERM...
(This evening through Friday)
Issued at 108 PM PDT Thu May 9 2024

The peak of the heat event has started with highs today ranging from
the low to mid 70s at the coastal regions, to the low to mid 80s at
the Bayshore and near Santa Cruz, to the upper 80s across the
interior valleys. The interaction between a strong ridge building
into British Columbia and the Pacific Northwest with a weak cut-off
low in the Great Basin is creating offshore flow across the region,
but this pattern is also one that will tend to create a "southerly
surge" of coastally trapped winds. Indeed, the high resolution HRRR
is showing a southerly surge coming up the Central Coast today,
abating overnight before a second surge travels farther north across
the California coast, beyond the Golden Gate and Point Arena. Those
two southerly surges will bring some relief to the coastal Central
Coast later today, and to the coastal regions tomorrow, with
Friday`s coastal highs expected to hover around the upper 60s to
lower 70s. The surges will also provide the only substantial chances
for cloud cover near the coastal areas impacted. That is little
comfort to those inland, where high temperatures will continue to
rise on Friday with the warmest spots bumping into the lower 90s.
Even the City, which does see some relief from the approaching
southerly surge, is expected to top out in the upper 70s tomorrow.

The region will generally see a Minor HeatRisk today and Friday,
with a Moderate HeatRisk for the interior regions of the North Bay,
East Bay, and South Bay. This corresponds to a low to moderate risk
of heat-related illnesses for vulnerable populations (children, the
elderly, pregnant women, people without adequate cooling, and people
with certain medical conditions). 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.

&&

.LONG TERM...
(Friday night through next Wednesday)
Issued at 108 PM PDT Thu May 9 2024

As the upper level ridge weakens as it moves through the Pacific
Northwest over the weekend, onshore flow will begin to reassert
itself. Coastal regions will continue to cool down and reach
seasonal average highs of around the upper 50s to lower 60s by the
early part of next week. The interior will continue to remain warmer
than seasonal averages, but not as warm as the forecast for Friday,
with highs generally in the low to mid 80s by the early part of next
week. Ensemble model clusters are in agreement over a new ridge
expected to approach the Pacific Northwest by Tuesday, but its
evolution after that point remains unclear.

&&

.AVIATION...
(18Z TAFS)
Issued at 1038 AM PDT Thu May 9 2024

VFR thanks to offshore flow. Winds are still breezy to gusty at
times, but less than yesterday. LLWS is less with stronger sfc
winds and decreasing winds aloft - better mixing. Hi-res models
show a southerly surge developing tonight with S winds already
developing along the Central Coast. Low cig impacts tonight look
to be mainly confined to MRY Bay region.

Vicinity of SFO...VFR through the period. Breezy to gusty NE flow
persisting through this afternoon before switching onshore late.
Low clouds associated with S surge remain outside of Golden Gate
through tonight.

SFO Bridge Approach...similar to SFO.

Monterey Bay Terminals...VFR through early tonight. Included some
cigs for KSNS early Friday due to low cigs sneaking up the Central
Coast. Ensemble guidance shows a 60-70% chc for low cigs at KSNS.
KMRY on the other hand are much lower at 15-20% and will only do
SCT cigs.

&&

.MARINE...
(Today through Tuesday)
Issued at 958 AM PDT Thu May 9 2024

High pressure to the north will maintain light to moderately
northerly winds for most of the coastal waters today. However,
winds will be locally more southerly along the Big Sur and
Monterey Bay region. Otherwise, gentle breezes out of the north
and northwest continue through the weekend first portion of the
weekend. Dry weather continues through the forecast period as high
pressure dominates.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 3 PM PDT this afternoon for Pt Pinos
     to Pt Piedras Blancas 0-10 nm.

&&

$$

SHORT TERM...DialH
LONG TERM....DialH
AVIATION...MM
MARINE...MM

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