209
FXUS66 KMTR 022316
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
416 PM PDT Tue Jul 2 2024

...New SYNOPSIS, SHORT TERM, LONG TERM, FIRE WEATHER...

.SYNOPSIS...
Issued at 158 PM PDT Tue Jul 2 2024

Significant and potentially deadly heat wave begins today lasting
into next week. Fire and heat highlights have been extended as
confidence in this pattern prolonging increases. Gusty afternoon
winds and critically dry fuels will lead to elevated fire weather
concerns through the weekend.

&&

.SHORT TERM...
(This evening through Wednesday)
Issued at 158 PM PDT Tue Jul 2 2024

Current temperatures are running about 10-20 degrees warmer than
24 hours ago as the high pressure builds in. Main changes for
today have been extending and adding to our current hazards. I
will list out the changes here and talk more about them in the
next section since they carry over into the "long term". The Heat
Advisory for San Francisco has been extended to include Thursday.
The Heat Advisory and Excessive Heat Warning for all other
locations originally included have been extended to NEXT Tuesday
night. The Red Flag Warnings in the North Bay, Santa Cruz Mtns,
and East Bay Hills have been extended to Friday morning. Finally,
a Fire Weather Watch was added for interior portions of Monterey
and San Bentio Counties, Santa Lucia, and the Southern Salinas
Valley for Friday through Sunday. In terms of the forecast from
today into Wednesday, there will be no significant change. Some
locations may see a degree or two taken off their highs while
other will see a degree or two added. Wednesday afternoon, there
is a very weak mid-level perturbation that will bring some degree
of marine influence to coastal areas and locations around the Bay.
While not a significant or even noticeable cool off by any means
for most, this may help to limit high temps a bit for San
Francisco Wednesday evening going into Thursday. On to the long
term to discuss what we expect to happen going forward.

&&

.LONG TERM...
(Thursday and beyond)
Issued at 158 PM PDT Tue Jul 2 2024

The heat isn`t going anywhere any time soon. Long range guidance
and cluster analysis strongly suggest this pattern is here to
stay through at least the beginning of next week. Some areas may
see a couple of degrees shaved off before the weekend, but it will
stay hot. A secondary peak is expected by the weekend into early
next week. While it may seem manageable based on looking at a
single day of these temps, the length of this event will present
an extremely dangerous and potentially historic event. Jogging
back in "recent" memory, to find the next most significant heat
event in terms of overall scale and longevity, you have to look
back to 2006. Sure, some locations have seen higher temps in more
recent memory, but this many days in a row may actually be
challenging some records based on the current forecast. How long
will this actually last? Good question. Taking a look at the
ensemble guidance for 850 mb temps...the forecast mean for OAK
remains above the 90th percentile and near the maximum moving
average through NEXT Friday, July 12. This is especially alarming
when compared with a look at how models are handling the overall
pattern. In the aforementioned cluster analysis, only 2% of total
members support a flattening of the ridge by mid-to-late next
week. This strongly suggests that there is high confidence in this
pattern and associated heat wave lasting through the forecast
period. This aided in the decision to extended the Excessive Heat
Warning out for 8 consecutive days, an unprecedented action from
our office.

It cannot be stressed enough that this is an exceptionally
dangerous and lethal situation. It may not seem so if you live
near the coast, but an event of this scale, magnitude, and
longevity will likely rival anything we`ve seen in the last 18
years for inland areas. Several days of temperatures well above
normal and little relief overnight will lead to compounding
effects among people and infrastructure, with the possibility of
numerous heat related fatalities and rolling black outs. Heat is
the number one weather related killer in the United States. By
this weekend, it is VERY LIKELY that we add to that statistic if
preparations are not taken seriously.

&&

.AVIATION...
(18Z TAFS)
Issued at 1033 AM PDT Tue Jul 2 2024

Satellite shows clear skies across the region. With the slow
moving high pressure system moving closer to our area, expect VFR
to prevail through the TAF period for most terminals with the
exception of Monterey Bay sites. With the compression of the
marine layer, expect some coastal ares to see low ceilings and
visibility overnight into the early morning hours. Winds will
become breezy this afternoon, with a onshore direction before
becoming light and variable tonight. There are some concerns for
LLWS for the North Bay overnight but had low confidence to include
at this moment.

Vicinity of SFO...VFR will prevail through the TAF period. W/NW
winds will become breezy this afternoon, with moments of gusty winds
up to 25 knots. Winds become light this evening into the morning.
Breezy conditions return by tomorrow afternoon.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR through the day with IFR/LIFR
conditions redeveloping tonight. Confidence is moderate due to lack
of agreement on model guidance. Therefore, clearing timing is
uncertain and may occur earlier than 15Z. N/NW winds will become
breezy this afternoon, but will return to light to moderate
overnight.

&&

.MARINE...
(Today through Sunday)
Issued at 1033 AM PDT Tue Jul 2 2024

Fresh to strong northerly winds continue over the outer coastal
waters today, with gale force gusts possible in the northern outer
waters through Tuesday night. Winds will diminish and become
moderate to fresh by mid- week as surface high pressure
strengthens and moves eastward. North to northwest winds prevail
through the forecast period but wind direction may become more
variable by late week as winds weaken. Elevated significant wave
heights between 10-12 feet continue through mid- week before
abating by the late week. Portions of the northern outer waters
may see peak wave heights between 12-16 feet through mid-week.

&&

.FIRE WEATHER...
Issued at 354 PM PDT Tue Jul 2 2024

Red Flag Warnings currently in effect for high elevations of the
North Bay, East Bay Hills, and the Santa Cruz Mtns have been
extended to 5AM Friday. This decision was made due to a
combination of continued low RH in the teens, very dry fuels, and
the 4th of July holiday. Fuels are quickly curing and will see no
relief through this weekend. In fact, 10 and 100 hour fuels are
near historic levels in the North Bay in regard to the energy
release component going into the weekend. The same fuels in the
Diablo Range and Santa Cruz Mtns aren`t far behind. Further south,
things start to dry out more this weekend. A Fire Weather Watch is
in effect for the Santa Lucia Range, Interior Monterey and San
Benito county, and the Southern Salinas Valley from Friday morning
to Sunday night.

Behringer

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Coastal Flood Advisory until 11 PM PDT Wednesday for CAZ006-506-
     508.

     Heat Advisory until 7 PM PDT Thursday for CAZ006.

     Excessive Heat Warning until 11 PM PDT Tuesday for CAZ502>504-
     506-510-512>518.

     Red Flag Warning until 5 AM PDT Friday for CAZ502>504-512-515.

     Heat Advisory until 11 PM PDT Tuesday for CAZ508-528-529.

     Fire Weather Watch from Friday morning through Sunday evening
     for CAZ516>518.

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

     Gale Warning until 9 AM PDT Wednesday for Pt Arena to Pt Reyes
     10-60 NM.

     Small Craft Advisory until 9 PM PDT this evening for Pigeon Pt
     to Pt Pinos 10-60 NM.

&&

$$

SHORT TERM...Behringer
LONG TERM....Behringer
AVIATION...SO
MARINE...SO

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