881
FXUS66 KMTR 241928
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
1228 PM PDT Tue Sep 24 2024

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

.SYNOPSIS...
Issued at 1227 PM PDT Tue Sep 24 2024

Heat Advisory continues in the interior East Bay through this
evening. Temperatures return to near the seasonal average on
Wednesday, slightly warming by Friday.

&&

.SHORT TERM...
(This evening through Wednesday)
Issued at 1227 PM PDT Tue Sep 24 2024

Today marks a last gasp of warm weather as an upper level ridge
moves into the Northern Rockies, and a weak upper level low
progresses northwards off of, and paralleling, the California
Coast. The lastest RTMA 24-hour temperature trends show temperatures
around 5 to 10 degrees above this time yesterday in the inland
regions, and beginning to trend cooler than this time yesterday west
of the coastal ranges and into the Salinas area. High temperatures
today range from the mid 90s to near 100 in the inland valleys, the
upper 70s to the 80s in the Bayshore, and the mid 60s to lower 70s
along the Pacific coast.

A Heat Advisory continues in the interior East Bay through 8 PM
tonight, due to the widespread risk for heat related illnesses for
sensitive populations (children, the elderly, pregnant women, those
with certain medical conditions), and the possibility for heat-
related impacts for everyone without adequate hydration and/or
cooling. Here`s a reminder about heat safety:

* 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.

An upper level trough builds into the eastern Pacific through the
day. As it does so, the weak upper level low splits, with part of
the energy continuing northward to merge into the upper level low
and the rest remaining offshore to lurk off Point Conception.
Temperatures should return to the seasonal average by Wednesday,
when morning lows range in the 50s to the low 60s in the valleys, to
the mid to upper 60s in the higher elevations, while highs cool to
the upper 70s to mid 80s inland and the low to mid 60s along the
Pacific coast. Breezy onshore winds are expected each afternoon and
evening, and a redeveloping marine layer supports the return of the
stratus deck at the immediate coast through the day and should
facilitate the return of inland stratus into most of the valleys.

&&

.LONG TERM...
(Wednesday night through next Monday)
Issued at 1227 PM PDT Tue Sep 24 2024

A zonal pattern develops towards our north on Thursday, while a weak
upper high develops over the Desert Southwest and the low meanders
towards the state. As a result, temperatures should start to warm
back up with inland highs into the 90s by Friday, paring back to the
mid to upper 80s for the upcoming weekend. Model output is beginning
to show the potential for light offshore flow during the night and
morning hours this weekend. However, confidence in any specific
impacts are too low to note in fire weather products at this time.
CPC outlooks continue to show a lean towards temperatures above, and
precipitation below, seasonal averages through the first week of
October.

&&

.AVIATION...
(18Z TAFS)
Issued at 1053 AM PDT Tue Sep 24 2024

As the heat ends a southerly surge is moving northerly along the
coast and coastal waters. Impacts this morning were confined to
mainly Monterey Bay terminals. In the near term, VFR conditions
will prevail. However, by this evening the surge will usher clouds
inland. First impacts will once again be for Monterey Bay
terminal and then inland valleys/bays. The first night of a surge
is usually shallow so cigs will be more in the IFR to MVFR range.
Some fog will also be possible (15-25%).

Vicinity of SFO...VFR with breezy NW winds late this afternoon.
CIGS AOB 1k feet will move inside the bay overnight and impact
operations for the Wednesday AM rush.

SFO Bridge Approach...Similar to SFO,but cigs may arrive sooner
and dissipate later than over the actual runways.

Monterey Bay Terminals...VFR through this afternoon, but cigs
return early this evening.

&&

.MARINE...
(Today through Sunday)
Issued at 921 AM PDT Tue Sep 24 2024

Light to locally moderate northwesterly flow will prevail over
the coastal waters. Strongest winds will be north of Point Reyes
over the outer waters. Breezy onshore flow will continue through
the West Delta each afternoon. A passing disturbance over the
Pacific Northwest will result in stronger northerly flow and
builds seas Wednesday night into Thursday.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory until 8 PM PDT this evening for CAZ510-515.

PZ...None.
&&

$$

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

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