000
FXUS66 KMTR 280952
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
252 AM PDT Thu Sep 28 2023

...New SYNOPSIS, SHORT TERM, LONG TERM, MARINE...

.SYNOPSIS...
Issued at 243 AM PDT Thu Sep 28 2023

Seasonable temperatures and breezy onshore winds expected today.
Rain is looking more probable across the area Friday into
Saturday with expected accumulations generally less than 0.25".
Warmer and drier conditions return briefly by midweek next week.

&&

.SHORT TERM...
(Today and tonight)
Issued at 243 AM PDT Thu Sep 28 2023

Marine layer inversion is redeveloping early this morning under more
stable conditions. 500 mb temps will continue to warm through the
day today, which will bring warmer, near seasonable daytime temps
across the area. Max temps this afternoon will be a few degrees
warmer compared to Wednesday across the interior. Expecting
another round of breezy onshore winds with locally gusty
conditions near the coast/coastal gaps.

&&

.LONG TERM...
(Friday through Wednesday)
Issued at 243 AM PDT Thu Sep 28 2023

Upper low is on track to dig southward across the West Coast
Friday into Saturday as ridging across the E Pacific becomes more
amplified. Guidance continues to support a more westerly track as
this low digs south, resulting in wetter conditions and onshore
flow for our area. Confidence is increasing on widespread precip
chances. Over the last 24 hours, QPF and PoPs have trended higher
with widespread 30-50% PoPs in the forecast. Fri-Sat forecasted
rainfall amounts range from a few hundredths of an inch across the
North Bay to 0.3" over favored terrain across the Central Coast.
NBM has a 20-40% chance that the Bay Area and Central Coast get at
least 0.10" with highest chances across the Santa Cruz Mtns,
Diablo Range, and Santa Lucias.

In addition to rain chances, cooler air aloft from this deep low
will help to destabilize air Saturday morning, which has introduced
the slight chance of wet thunderstorms to the official forecast for
southern portions of the cwa. Stronger W/NW flow aloft, MUCAPE ~100-
300 J/Kg, and a passing vort max will favor highest chances for
storms (still low at 15%) across southern Monterey and San Benito
Counties early Sat. Post-frontal showers are possible Sunday
morning, but lower confidence for that scenario.

High pressure from the E Pacific will move east early to midweek
next week as upper low treks into the Great Basin, which will
prompt warmer and drier conditions by midweek.


&&

.AVIATION...
(06Z TAFS)
Issued at 1046 PM PDT Wed Sep 27 2023

VFR continues through much of the TAF period for most terminals. The
one exception to this is Monterey Bay who is expected to develop
MVFR CIGs towards midnight. Otherwise, clear conditions prevail with
winds weakening into the night for most terminals. Winds increase
into the afternoon of Thursday to become onshore and breezy around
10-14 knots, and locally gusty near the SF Bay terminals.

Vicinity of SFO... VFR through the TAF period. Onshore winds have
begun to weaken but look to remain slightly elevated around 5-10
knots overnight. Though, gusty onshore winds similar to those seen
today return into the late afternoon of Thursday.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR conditions turn to become MVFR towards
midnight, with clearing to VFR expected again towards 15Z, though
low clouds may linger. Winds weak in the overnight hours this
morning, then increasing into the afternoon to become breezy around
12 knots.

&&

.MARINE...
(Today through Tuesday)
Issued at 243 AM PDT Thu Sep 28 2023

Northwesterly winds continue to strengthen, with gales beginning
to develop over much of the outer waters and coastal jet regions.
Gales last through much of the day today, then weakening towards
late Friday morning to become fresh. Northwest swell continues to
diminish, though large wind waves build overnight tonight and
persist through the weekend. Both winds and waves will combine to
create dangerous conditions for small craft through the remainder
of the week. Chances of rain approach towards Saturday evening
with the arrival of a new low pressure system.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 3 AM PDT early this morning for
     PZZ535.

     Small Craft Advisory from 3 PM this afternoon to 9 PM PDT this
     evening for PZZ535.

     Small Craft Advisory until 3 PM PDT this afternoon for PZZ540-
     560.

     Gale Warning from 3 PM this afternoon to 3 AM PDT Friday for
     PZZ540.

     Small Craft Advisory until 3 AM PDT Friday for PZZ545.

     Gale Warning from 3 PM this afternoon to 9 PM PDT this evening
     for PZZ560.

     Gale Warning until 9 AM PDT Friday for PZZ565.

     Gale Warning until 3 AM PDT Friday for PZZ570-575.

&&

$$

SHORT TERM...McCorkle
LONG TERM....McCorkle
AVIATION...AC
MARINE...AC

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NWS MTR Office Area Forecast Discussion

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print "<p>High Precipatation<br/><br/>$usaprecip</p>\n";
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USA Extremes for Tuesday, September 26, 2023

High Temperature

105°F at Phoenix Airport, AZ

Low Temperature

24°F at Mammoth Lakes Mammoth Yosemite Ap, CA

High Precipatation

6.14in at Brunswick-mckinnon Arpt, GA

Data courtesy of NWS-CPC

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