242
FXUS66 KMTR 230545
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
1045 PM PDT Sat Jun 22 2024

...New AVIATION, MARINE...

.SYNOPSIS...
Issued at 105 PM PDT Sat Jun 22 2024

Hot temperatures peak this afternoon with a Heat Advisory in effect
through the evening for the interior regions with a moderate risk of
heat-related illnesses. Temperatures moderate through the early part
of next week, but remain warm across the interior.

&&

.UPDATE...
Issued at 859 PM PDT Sat Jun 22 2024

Largely tranquil weather is on tap for this evening across the
Bay Area and Central Coast. We`ll look to expire the Heat Advisory
on time later this evening after a day of hot conditions (just
below 105 across the East Bay interior). With the higher than
normal high tides, we`ve elected to go with a Coastal Flood
Advisory to address largely minor flooding potential across
portions of the North Bay. While impacts are expected to be minor,
areas near and along the immediate bayshore will be prone to
inundation. Be sure to avoid low-lying areas tonight.

We`re continuing to examine the potential for high-based
convection Sunday afternoon, Sunday night, and even a non-zero
potential on Monday and Tuesday across southern portions of San
Benito and Monterey counties. Meager, but potentially sufficient
moisture (some from remnants from tropical storm that impacted
South Texas) will slide to the west and to the north across the
Central Valley ahead of a diffuse upper trough. Forecast PWATs
for the area would actually increase into the 75th percentile for
this time of year and are expected to range between 0.75-1.0".
The highest PWATs should reside across southern portions of the
area.

3km NAM forecast soundings for areas near and just north of Paso
Robles actually show moistening low to mid-levels with
respectable lapse rates just under 8 C/km in this same layer.
Below this layer, however, it`s quite dry and thus any convection
that develops will produce little to no rain at the surface.
However, with MUCAPE values in excess of 1000 J/kg, there will be
a potential for dry lightning. In addition, 1 and 10 hour fuels
(such as grasses and shrubs) continue to cure, so there`s a
potential for additional ignitions. due to lightning. This
coupled with erratic outflow winds would in theory support fire
spread. All that said, the potential for actual thunderstorm
development is around 10-15%. As such, we`ll forgo any fire
weather headlines and handle messaging in graphics and partner
briefings. If this changes, then messaging will need to be a bit
more aggressive (fire weather headlines and/or Red Flag products).

Otherwise, the rest of the short term forecast is in good shape
and updated products will be transmitted shortly.

&&

.SHORT TERM...
(This evening through Sunday)
Issued at 105 PM PDT Sat Jun 22 2024

A Heat Advisory remains in effect until 10 PM across the interior
where temperatures are forecast to reach into the mid 90`s to near
105 degrees this afternoon. This will result in Moderate HeatRisk
across these areas with temperatures gradually cooling this evening.
This means that there is a risk of heat-related illnesses for most
people sensitive to heat, including children, the elderly, pregnant
women, those working or living outside, and those with certain
medical conditions. Here are heat safety tips:

* Stay hydrated and drink plenty of water.
* Wear lightweight, light-colored clothing.
* Reduce time spent outdoors or stay in the shade.
* Never leave people or pets unattended in vehicles.
* Use sunscreen if going to the coast or the pool.

Tonight, temperatures will generally cool into the mid-to-upper 50`s
for most locations away from the immediate coast with some upper
40`s in those locations. However, warm temperatures will persist
across the higher elevations where temperatures will only dip into
the upper 60`s to upper 70`s. Low clouds and/or fog will also return
to the region this evening, yet will penetrate less inland overnight
as high pressure continues to compresses the marine layer.

Temperatures on Sunday begin to cool slightly (especially across the
interior) as onshore flow increases and the marine layer deepens.
Thus, afternoon maximum temperatures on Sunday are expected to range
from the upper 80`s to mid 90`s across the interior with only
isolated pockets warming into the upper 90`s to near 100 degrees.
Cooler conditions will prevail near the coast with upper 50`s to
upper 60`s, 70`s just inland away from the immediate coastline, and
low-to-mid 70`s to low 80`s around the bayshore.

&&

.LONG TERM...
(Sunday night through next Friday)
Issued at 105 PM PDT Sat Jun 22 2024

An area of mid-to-upper level moisture will move northward into the
region on Tuesday resulting in increased mid/upper level clouds. We
will need to watch this for any potential for high-based convection,
yet the treat remains very low as this time. By late week,
temperatures trend cooler across the interior in response to an
upper level trough impacting the region with increased onshore flow.

The latest CPC outlook continues to suggest temperatures near or
above seasonal averages, and precipitation at or below seasonal
averages (noting that at this point in the year, seasonal average
precipitation is very low) continue into the first days of July.

&&

.AVIATION...
(06Z TAFS)
Issued at 1031 PM PDT Sat Jun 22 2024

Satellite imagery shows stratus across the Monterey Bay region,
with the rest of the region generally clear. Stratus will build
across the coastal regions through the night, with moderate
confidence of ceilings at the North Bay and northern SF Bay
terminals. Stratus will retreat to the immediate coast Sunday
morning with breezy onshore winds developing in the afternoon and
evening. Stratus expected to build back in Sunday evening, mostly
after the end of the 24-hour TAF period.

Vicinity of SFO...Currently VFR. Moderate confidence of an IFR
ceiling at the terminal early morning on Sunday, with some high-
resolution models still showing VFR through the night. If ceilings
do form, expect clearing by 16Z. Breezy west-northwest winds with
gusts up to 20 knots will develop on Sunday afternoon, diminishing
in the evening. Some model output is showing a chance for
ceilings on Sunday night, mostly after the end of the TAF period.

SFO Bridge Approach...Lower confidence of stratus impacts to the
south of the terminal. Otherwise similar to SFO.

Monterey Bay Terminals...LIFR stratus through the night with the
chance for fog at MRY. Clearing is expected later on Sunday
morning, with breezy onshore winds developing in the afternoon.
Stratus will return to the terminals Sunday evening near the end
of the TAF period.

&&

.MARINE...
(Tonight through next Friday)
Issued at 1002 PM PDT Sat Jun 22 2024

  Strong, northwest winds continue over the northern outer waters
through Monday. Fresh gusts remain possible over the southern
outer waters and portions of the northern interior coastal waters.
Wave heights up to 10 feet are expected throughout the northern
outer waters with significant wave heights diminishing below 10
feet by the middle of the work week. Conditions hazardous to small
crafts remain possible through the middle of the work week across
the northern outer waters. Light southerly swell and moderate NW
swell continue over the coastal waters through the beginning of
next week.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Coastal Flood Advisory until 3 AM PDT Sunday for CAZ506.

PZ...Small Craft Advisory from 9 AM to 9 PM PDT Sunday for Pt Arena
     to Pt Reyes 0-10 nm.

     Small Craft Advisory until 3 PM PDT Monday for Pt Arena to Pt
     Reyes 10-60 NM.

&&

$$

SHORT TERM...RGass
LONG TERM....RGass
AVIATION...DialH
MARINE...SO

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