432
FXUS66 KMTR 060734
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
1234 AM PDT Thu Jun 6 2024

...New AVIATION, MARINE...

.SYNOPSIS...
Issued at 1255 PM PDT Wed Jun 5 2024

Hot again today as the heatwave peaks. A couple of degrees cooler
Thursday, followed by further cooling Friday. Above average
temperatures hang around through the weekend. Another potential
hot period mid next week.

&&

.UPDATE...
Issued at 754 PM PDT Wed Jun 5 2024

Another warm to hot day today, especially in locations further from
the coast. We thought we had a record high today at Half Moon Bay,
but further review of the data and surrounding stations makes us
think that the observation was erroneous. Most of the region
should start to cool down tomorrow, with the inland valleys seeing
highs from the 90s into the low 100s in the most inland places.
The operations floor considered ending the Heat Advisory early as
a result of the cooldown. However, the combination of temperatures
remaining above seasonal averages, and the cumulative effect of
the last two days of heat, have caused us to keep the Heat
Advisory in effect into tomorrow.

DialH

&&

.SHORT TERM...
(This evening through Thursday)
Issued at 1255 PM PDT Wed Jun 5 2024

Temperature today running pretty well in line with the forecast.
Based off of temperatures yesterday, kept today`s forecast nudged
toward the 90th percentile. Many locations will see highs today
very similar to yesterday, a few degrees higher for areas south of
the SF Bay Area. The only exception would be the immediate
coastline where onshore flow is battling to keep the shallow
marine layer intact. These areas are running a couple of degrees
cooler. By Thursday, a shortwave trough around the periphery of a
deep upper low in the Gulf of Alaska traverses through the West
Coast, deepening the marine layer a bit and slightly enhancing the
onshore flow. This will cool temperatures further for most
locations, aside from the far inland spots like interior Napa, far
eastern Alameda and Contra Costa, and interior Monterey/San
Benito.

&&

.LONG TERM...
(Thursday night through next Tuesday)
Issued at 1255 PM PDT Wed Jun 5 2024

The Heat Advisory expires at midnight Thursday night with further
deepening of the marine layer and additional cooling expected by
Friday into the weekend. Above average temperatures persist
through the weekend as upper level ridging dominates the pattern
over the west. However, persistent onshore flow and a weak trough
over the eastern Pacific should moderate our temps enough to keep
them a bit lower into early next week. The middle of next week
looks like our next potentially impactful warm period as the ridge
builds once again.

&&

.AVIATION...
(06Z TAFS)
Issued at 1234 AM PDT Thu Jun 6 2024

Sky condition is VFR mixed with MVFR surface visibility in haze
along the coastline. Microphysics satellite imagery shows fog
slowly moving northward along the Big Sur Coast connected to an
extensive pool of stratus and fog from Point Conception and areas
to the southeast through southwest. In our forecast area the
marine layer depth varies from a few hundred feet along the coast
of the North Bay to almost 1,000 feet along the north Central
Coast. Bodega Bay and Fort Ord profilers and Wednesday evening`s
Oakland upper sounding show the marine layer temperature inversion
is still strong. The ACV-SFO pressure gradient (northerly wind)
is 6.2 mb and slowly decreasing, the SBA-SFO and SMX-SFO pressure
gradients (southerly wind) have strengthened to 2.7 mb and 2.6 mb
respectively, while the SFO-SAC pressure gradient is onshore at
2.3 mb.

As of current, the meso-scale model output are under-forecasting
the aforementioned southerly pressure gradient(s) by at least 50%.
With the newly developed combined northerly and (under-forecasted)
southerly wind potential coupled to the onshore wind, am expecting
at least what the meso-scale models show for cooling at 1000 mb
(~300 feet) and at 925 mb (~2500 feet), therefore the lower level
temperature inversion should weaken somewhat today below the 850
mb level (~5000 feet). Bottom line, this and current nocturnal
radiative cooling provides coastal stratus and fog /VLIFR-IFR/ a
foothold for additional development through daybreak, then mixing
out temporarily during the day with the usual vertical mixing then
redeveloping tonight and Friday morning.

Vicinity of SFO...VFR. West wind 5 to 15 knots through this morning,
increasing to 18 to 25 knots in the afternoon and evening. West wind
decreasing tonight and early Friday morning to near 10 knots.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR then LIFR-IFR developing early this
morning between 12z-16z, stratus and fog mixing out after 16z to
VFR during the day. West to northwest winds in the afternoon,
possibly shifting to southwest at KMRY depending how strong the
southerly wind reversal is during the day. KSNS surface wind
northwesterly and becoming gusty in the afternoon. Stratus /IFR/
forecast this evening and likely to continue tonight and Friday
morning.

&&

.MARINE...
(Tonight through next Tuesday)
Issued at 1043 PM PDT Wed Jun 5 2024

Moderate northerly winds will persist through Thursday before
gradually easing into Friday. The stronger winds through Thursday
will lead to hazardous conditions for small craft. A moderate
period Northwest swell will continue impact the coastal waters
through Thursday. Swell will diminish Friday through Saturday
before waves build again towards the end of the period.

&&

.BEACHES...
Issued at 505 PM PDT Wed Jun 5 2024

A Beach Hazards Statement is in effect from Wednesday morning
through Thursday evening.

Forecast remains on track. Moderate period swell is entering the
coastal waters at 14-17 seconds with heights varying 7-11 feet.
The would generate breaking waves of 8-15 feet with locally
higher waves at favored break points. Sneaker waves can run over
100 ft up a dry beach, pulling people in the water from rocks,
jetties, and beaches. Inexperienced swimmers should stay out of
the water. Observe the ocean for 20 minutes before relaxing on the
beach. The hot weather inland will lead to more people visiting
the beach this week. Know where lifeguards are, obey their
instructions, and never turn your back on the ocean!

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Beach Hazards Statement through Thursday evening for CAZ006-505-
     509-530.

     Heat Advisory until midnight PDT Thursday night for CAZ503-504-
     506-510-512>516-518.

PZ...Small Craft Advisory until 3 AM PDT Friday for Pt Arena to Pt
     Reyes 0-10 nm-Pt Arena to Pt Reyes 10-60 NM.

     Small Craft Advisory until 9 PM PDT Thursday for Pigeon Pt to Pt
     Pinos 10-60 NM-Pt Reyes to Pigeon Pt 0-10 nm.

&&

$$

SHORT TERM...Behringer
LONG TERM....Behringer
AVIATION...Canepa
MARINE...MM

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