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NWS Forecast Area Discussion - San Francisco Area

150
FXUS66 KMTR 200243
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
743 PM PDT Fri Jul 19 2024

...New UPDATE...

.SYNOPSIS...
Issued at 302 AM PDT Fri Jul 19 2024

Warm again going into the weekend. Short cool down Sunday with
another warm up on the way through next week.

&&

.UPDATE...
Issued at 743 PM PDT Fri Jul 19 2024

Beautiful clear skies as we approach the night. Temperatures still
remain higher than 24 hours ago with a 5-18 degree difference across
the region. Temperatures are expected to return to normal seasonal
temperatures and will see mostly 80s and 90s over the weekend,
therefore the Heat Advisory will expire tonight. With the hot
temperatures today, relative humidity have dropped a bit more, which
will continue elevated fire concerns. Conditions remain on track,
therefore no changes were made to the forecast.

&&

.SHORT TERM...
(This evening through Saturday)
Issued at 301 PM PDT Fri Jul 19 2024

Hot weather continues through today before closer to seasonal
temperatures return Saturday. A heat advisory is currently in effect
for interior portions of the Bay Area and the Central Coast through
11PM tonight when it will be allowed to expire. Highs are generally
running 5 to 12 degrees above average inland while coastal
temperatures continue to be closer to seasonal averages. Widespread
moderate heat risk continues through Friday. Those who are sensitive
to heat should take precautions to avoid being outdoors during peak
heating (afternoon/evening hours) and drink plenty of water while
participating in any outdoors activities.

Not a fan of today`s heat? You`re in luck because
temperatures will drop 5 to 6 degrees on Saturday as a weak
shortwave trough moves inland over the Western United States. For
the past few days building high pressure has helped to keep the
marine layer compressed below 1000 ft which has kept stratus more
patchy and confined closer to the coastline. The passage of this
shortwave trough will allow the marine layer to deepen slightly and
for stratus to spread slightly farther inland by Saturday night.
Warmer and drier conditions in combination with locally gustier
winds across mountain gaps/passes will lead to elevated fire weather
concerns in the North/East/South Bay and in interior Monterey/San
Benito Counties Friday and Saturday. However, fair to good
overnight relative humidity recoveries and decent daytime minimum
relative humidity values will reduce the overall fire weather
risk.

&&

.LONG TERM...
(Saturday night through next Thursday)
Issued at 301 PM PDT Fri Jul 19 2024

Seasonal temperatures continue Sunday before our next warm up begins
Monday. By Monday, the shortwave trough which brought us cooler
weather will have moved out of our region and upper level ridging
will build again. Forecast high temperatures, thankfully, continue
to look cooler than those observed during our previous early July
heatwave. Across the interior, temperatures will peak in the 90s to
low 100s. Temperatures cool down the closer to the coast you go with
highs close to the coast peaking in the upper 70s to 80s but only
peaking in the mid 60s to low 70s directly along the coastline. The
most recent guidance suggests Monday and Tuesday to be the peak of
the heatwave for our region with temperatures trending a few degrees
(1-3 degrees) cooler Wednesday and Thursday. Moderate heat risk will
become more widespread Monday through Thursday with pockets of major
heat risk expected in elevated terrain across the East/South Bay and
interior Central Coast. Take advantage of the more seasonal weather
Saturday and Sunday and take care of any activities that require you
to be outdoors for long periods of time.

Looking past this forecast period, high temperatures are expected to
drop off more significantly beginning Friday. CPC guidance indicates
that cooler, more seasonal temperatures are likely to return by the
end of the July and potentially bring some relief from the hot
weather through early August.

&&

.AVIATION...
(00Z TAFS)
Issued at 417 PM PDT Fri Jul 19 2024

VFR across the region with breezy onshore winds setting up through
the evening. Stratus development tonight is limited to the Central
Coast and Monterey Bay regions, with very low confidence of stratus
near OAK. Beyond the 24-hour TAF period, winds look to be much
gustier on Saturday afternoon and evening.

Vicinity of SFO... VFR through the TAF period with low confidence
for stratus on Saturday evening. Winds will build through the
evening gusting up to 30 knots, with gusts abating overnight before
gusts in the 30-35 knot range resume Saturday afternoon and evening.
Low confidence in gusts above 35 knots on Saturday.

SFO Bridge Approach... Similar to SFO.

Monterey Bay Terminals... With the marine layer not as compressed as
yesterday, IFR stratus is set to return to the terminals late
tonight around 08-10Z. Low to moderate confidence in the timing of
any clearing on Saturday morning with model output suggesting some
chance of ceilings continuing beyond the end of the TAF period,
especially over MRY. Breezy onshore winds expected during the
afternoon and evening hours both today and Saturday.

&&

.MARINE...
(Tonight through next Wednesday)
Issued at 417 PM PDT Fri Jul 19 2024

Gusty northwest winds will increase tonight with strongest mainly
across the northern waters which will see gale force gusts. In
the unprotected waters, short period seas will build with wave
heights between 10-12 feet Friday and further deteriorate to very
rough by Sunday.

&&

.FIRE WEATHER...
Issued at 417 PM PDT Fri Jul 19 2024

...Near critical fire weather conditions continue through
Saturday due to hot and dry conditions inland...

Dry and warm conditions continue inland with very dry fine fuels
contributing to an increased risk of fire starts. This results in
near critical fire weather conditions through Saturday across the
interior regions of the North Bay, East Bay, South Bay, and
Monterey and San Benito counties. Onshore winds will develop each
afternoon and evening, with peak gusts in the gaps and passes up
to 30 to 40 miles per hour. The strongest gusts appear to develop
for the evening hours on Saturday, but as relative humidities are
expected to be recovering from daytime minimums during the period
of peak wind gusts, the alignment between dry air and high winds
is not there for acute fire weather concerns.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Coastal Flood Advisory until 2 AM PDT Tuesday for CAZ006-506-508.

     Heat Advisory until 11 PM PDT this evening for CAZ503-504-506-
     510-513>515-517-518.

PZ...Gale Warning until 9 PM PDT Saturday for Pigeon Pt to Pt Pinos
     10-60 NM-Pt Arena to Pt Reyes 0-10 nm-Pt Arena to Pt Reyes
     10-60 NM.

     Small Craft Advisory until 9 PM PDT Saturday for Pigeon Pt to Pt
     Pinos 0-10 nm-Pt Pinos to Pt Piedras Blancas 0-10 nm-Pt
     Reyes to Pigeon Pt 0-10 nm.

&&

$$

SHORT TERM...Kennedy
LONG TERM....Kennedy
AVIATION...DialH
MARINE...Murdock

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