563
FXUS66 KMTR 140003
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
503 PM PDT Sat Jul 13 2024

...New AVIATION, MARINE...

.SYNOPSIS...
Issued at 145 PM PDT Sat Jul 13 2024

Heat Advisory is in effect mainly inland portions of the Bay Area
and north Central Coast until 9 pm this evening. It`s still hot
inland, however relative cooling is taking place helping to ease
things a bit due to cloud cover along with a few isolated passing
showers through the afternoon. High temperatures will continue to
ease back to normal mid July highs in the mid 80s to 90s far inland
early to mid next week. Closer to the coast and nearby coastal
valleys a maritime influence will result in cooler daytime
temperatures.

&&

.SHORT TERM...
(This evening through Sunday)
Issued at 155 PM PDT Sat Jul 13 2024

We continue to closely monitor satellite, radar and observations
for incoming mid level moisture and instability from southern
California. So far we`re only seeing a few passing showers and
since high resolution model output shows plenty of convective
inhibition the expectation is this will continue to greatly limit
any potential for thunderstorm development through afternoon and
evening. There`s forecast steepening of the 700-500 mb temperature
lapse rates and weak mid level convective potential out ahead and
northeast of the 500 mb low, currently 275 miles west of Point
Conception, arriving late tonight and Sunday morning however just
above this the 500-300 mb layer is stable. From approx the 700 mb
level (~ 10,000 feet) downward through the 925 mb level (~ 2,500
feet) thermal ridging, stability remains in place tonight and
Sunday morning.

Warm to hot far inland again this afternoon, however cloud cover
will help reduce incoming solar input a little bit helping reduce
highs a little compared to Friday afternoon. Cooler temperatures
prevail along the coast and in the nearby coastal valleys due to
increasing maritime influence, including coastal stratus and fog.

&&

.LONG TERM...
(Sunday night through next Friday)
Issued at 155 PM PDT Sat Jul 13 2024

Summer continental surface heating continues to correspond to
strong 500 mb heights with a nearly stationary high pressure
system over the west with the center near the Four Corners. A
stable north hemispheric pattern shows signs of strengthening and
becoming unsteady again with five long wave troughs developing by
late next week. One long wave trough is forecast to slowly
progress eastward to along western North America while a long wave
ridge primarily strengthens over central Canada with an extension,
possibly the southern extension retrogressing toward the southwestern
states. The GEFS/EPS ensemble 850 mb mean temperature forecasts for
our forecast area climb back to 26 Celsius next weekend, not quite
as warm as of recent, but bears watching.

&&

.AVIATION...
(00Z TAFS)
Issued at 503 PM PDT Sat Jul 13 2024

VFR prevails through the mid evening, though stratus will begin to
fill into are terminals as the sun begins to set. Winds will ease
into the night to become light for most terminals. Stratus is likely
to bring IFR CIGs initially, eventually becoming LIFR in the early
morning of Sunday. There does remain some uncertainty as to whether
CIGs will lower to LIFR, as troughing just off of the coast could
lend just enough influence to help keep CIGs elevated. Therefore,
confidence is low-moderate on LIFR conditions developing. Aside from
this, stratus is expected to clear from terminals in the late
morning Sunday, leading to VFR conditions once more.

Vicinity of SFO...VFR lasts through the late night tonight, but
stratus is expected to begin to filter over the terminal beyond
sunset bringing low clouds. These low clouds are expected to
eventually form IFR CIGs in the early morning of Sunday. IFR lasts
through the late morning, then clearing to VFR. High clouds are
likely to be present through the remainder of the TAF period as
upper level moisture enters the region.

SFO Bridge Approach...Stratus will fill into the Bay in the early
morning of Sunday bringing low clouds.

Monterey Bay Terminals...Stratus will continue to fill in this
evening to bring initally IFR CIGs. Towards midnight, CIGs are
expected to lower to become LIFR and visibilities may reduce
slightly as fog and mist develops. LIFR conditions then last
through the late morning of Sunday. Clearing to VFR expected in
the late morning, with winds slowly increasing to become breezy
and onshore in the afternoon. High clouds will be present.

&&

.MARINE...
(Tonight through next Friday)
Issued at 503 PM PDT Sat Jul 13 2024

Slight chances of isolated light rains showers exist this weekend
over the waters, though any precipitation that does fall is most
likely to be drizzle. Otherwise, gentle to moderate northerly
winds continue through the afternoon today but begin to turn more
southerly starting Sunday. These light southerly winds are
expected to continue through the middle part of next week, but
then turn to become more northwesterly beyond then.

&&

.FIRE WEATHER...
Issued at 1030 AM PDT Sat Jul 13 2024

Mid level cloud cover/moisture moving up from southern California
is resulting in widely scattered showers, a few spots have reported
a trace (and possibly light measurable precipitation) reaching the
ground. Forecast soundings show widespread convective inhibition
over our forecast area today i.e. stability greatly helping to
preclude thunderstorm development. Per satellite and high
resolution model output, mid level cloud cover over our forecast
area will help reduce incoming solar input today. 12z statistical
guidance shows slightly cooler temperature trends including inland
areas today. The marine layer temperature inversion at the mountain
tops is still quite warm, however 24 hour trends show cooler temperatures
almost everywhere this morning, also resulting in positive humidity
trends.

A well established marine layer with coastal stratus has recently
shown signs of deepening per Bodega Bay and Fort Ord profiler data.
The southerly and onshore pressure gradients and winds prevail which
will help usher higher humidity to the inland valleys, hills and
eventually mountain tops.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory until 9 PM PDT this evening for CAZ504-510-513>515-
     517-518.

PZ...None.
&&

$$

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

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