964
FXUS66 KMTR 280507
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
1007 PM PDT Thu Jun 27 2024

...New UPDATE, MARINE...

.SYNOPSIS...
Issued at 1113 AM PDT Thu Jun 27 2024

Pleasant temperatures into the weekend. Pattern change causes a
warm up early next week, with monitoring potential excessive heat
for the second half of next week.

&&

.UPDATE...
Issued at 1007 PM PDT Thu Jun 27 2024

Patchy coastal stratus and fog are redeveloping this evening, it`s
clear elsewhere per satellite imagery and surface observations.
Additional coastal stratus and fog are forecast to develop tonight
and Friday morning. Average temperatures today were near (1991-2020)
late June normals; a couple to a few degrees of warming mainly inland
will take place over the weekend, similarly on Monday. Weak upper level
troughing and onshore surface winds will continue into the weekend.

There`s good global model agreement that a high pressure system will
strengthen approx 1000 miles to the west of the Bay Area by late in
the weekend and Monday. Thereafter, the high is forecast to advance
eastward toward northern California, large scale downward vertical
motion (compressional warming) sending 850 mb temperatures upwards,
EPS/GEFS (27 Celsius) 850 mb temp means are near the max moving
average in comparison to Oakland upper air soundings long term
early July climatology. While recent deterministic output are
forecasting 850 mb temps higher, nearing 30C to 31C by July 5th-6th.
With large scale compression, expect the marine layer to do the same,
to be compressed to near sea level, while winds at this time do not
appear to become breezy to gusty offshore; a good idea however to
closely monitor because the global/mesoscale models sometimes will
under-forecast the ACV-SFO gradient (northerly wind) for example.
850 mb level (~5000 feet) temperatures are a usual reference
point for predicting forecast high temperatures at the surface
since sinking air parcels under a high pressure system will
typically warm dry adiabatically to the surface, daily solar input
connecting with these warmed air parcels, post sunrise temperatures
quickly warming up as a result. Forecast highs expected to warm up
to the 90s/lower 100s, hottest temps Tue-Thu, with likely carryover
of hot temps July 5th-6th. With respect to long term Bay Area stations
record high temperatures for the 4th of July, many still remain from
a 1905 heatwave, including another heatwave early July 1931.

Stay tuned to the latest forecast updates, it`s a good idea to plan
on above normal to well above normal hot temperatures next week. If
the high is slow to move then hot weather will linger to late next
week.

&&

.SHORT TERM...
(This afternoon through Friday)
Issued at 1113 AM PDT Thu Jun 27 2024

Satellite shows clear skies across our area with some high clouds
over far west over the ocean. With a semi-zonal flow, weather
conditions will be pretty similar to yesterday with low clouds
redeveloping tonight over the ocean. With breezy onshore winds, some
of the low clouds will be pushed inland along the coast. Soon as
diurnal heating starts to take place Friday morning, most of the
clouds will erode, causing another beautiful day with clear skies.
Temperatures tonight will be mostly in the 50s across the region.
Maximum temperatures Friday will be a bit warmer than today but
still around normal for this time of year. The maximum temperatures
near the coastal areas will see high 50s to mid 60s. Inland areas
will see mid 70s to upper 80s, with higher terrains seeing mid
90s.

&&

.LONG TERM...
(Friday night through next Wednesday)
Issued at 1113 AM PDT Thu Jun 27 2024

Weather conditions remain pretty consistent through the weekend into
the first half of next week. Ensemble shows that the trough will
continues to deepen, which will bring a continuation of coastal
stratus that develop overnight that can linger longer in the
mornings. Going into the weekend, max temperatures increase a bit to
mid 80s to mid 90s inland, and mostly 60s to low 70s along the
coast. Overnight temperatures will see mostly 50s to low 60s. Monday
will be the start of a pattern shift, where a high pressure system
building over the ocean, will cause temperatures to increase. NBM
continues to show max temperatures in the 90s inland with possible
triple digits for higher terrains starting Monday into Wednesday.
Coastal areas will also be impacted with temperatures in the mid to
upper 70s. Climate Prediction Center 6-10 temperature outlook also
highlights our area in 40-60% chance for above normal temperatures.
As we are still 4+ days out from the warm-up, stay tuned for any
updates and additional details about the weather conditions as we
head into the 4th of July weekend.

&&

.AVIATION...
(00Z TAFS)
Issued at 430 PM PDT Thu Jun 27 2024

VFR through the TAF period for the majority of terminals, with the
exception of a few coastal terminals. Onshore winds diminish tonight
to become light for most as the gradient eases. Terminals that do
see coastal stratus tonight are likely to see IFR conditions, with
Ft. Ord profiler currently showing the marine layer with a depth of
about 1000 feet. Coastal terminals that do develop IFR CIGs are
likely to see those CIGs erode just after sunrise, leading into VFR
conditions for the late morning and afternoon of Friday.

Vicinity of SFO...VFR through the TAF period, though SCT low clouds
are likely to crowd the terminal in the early morning of Friday as
stratus trickles in through the Golden Gate Gap. Winds ease, but
remain above 7 knots through the overnight. In the afternoon of
Friday, any low clouds are expected to mix out as diurnal heating
begins, with westerly winds increasing to become moderate and gusty
in the afternoon.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...IFR CIGs return in the night tonight as
stratus forms off the Monterey coastline. CIGs are expected to lower
to become LIFR just after midnight, however confidence on this is
only moderate given upper level troughing which could assist in
keeping CIGs more elevated. Nonetheless, stratus is expected to
clear and VFR returns in the late morning of Friday with breezy
westerly winds returning in the afternoon. Models suggest stratus
making a return in the mid evening of Friday.

&&

.MARINE...
(Tonight through next Wednesday)
Issued at 859 PM PDT Thu Jun 27 2024

Fresh to strong northwest winds persist into the next work week
before easing to become moderate across much of the waters. Wind
is the main driver for the Small Craft Advisories; however,
significant wave heights begin to build to 10-12 feet towards the
end of the period. Light southerly swell continues to move through
the waters alongside moderate northwesterly swell.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 3 AM PDT Saturday for Pigeon Pt to Pt
     Pinos 10-60 NM-Pt Arena to Pt Reyes 0-10 nm.

     Small Craft Advisory until 3 AM PDT Friday 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.

     Small Craft Advisory until 9 AM PDT Saturday for Pt Arena to Pt
     Reyes 10-60 NM.

&&

$$

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

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