Technical NOAA Weather Discussion

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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Prepared by Boulder-Creek.com Weather at: Fri Jul 19 22:30:03 PDT 2024
From the National Weather Service