Richardson Bay Park, California Weather Forecast Discussion

472
FXUS66 KMTR 202042
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
142 PM PDT Sat Sep 20 2025
...New SHORT TERM, LONG TERM...
.KEY MESSAGES...
Updated at 141 PM PDT Sat Sep 20 2025
- Warming trend through Monday and into Tuesday
- Weak offshore flow on Monday and Monday night in the higher
   terrain
- Rain showers and isolated thunderstorm chances return early
   next week
&&
.SHORT TERM...
Issued at 141 PM PDT Sat Sep 20 2025
(This evening through Sunday)
A mid/upper level cut off low pressure system remains off of the Bay
Area/Central Coast early this afternoon with 850 MB temperatures on
the rise. This is leading to the warming trend across the region
that is forecast to persist into tomorrow. Cumulus clouds are
developing across the higher terrain of the Central Coast and East
Bay where surface based CAPE is up to 650 J/kg. However, the
probability remains low (less than 10%) for any of these to develop
into showers/thunderstorms.
The HRRR is showing increasing likelihood for low clouds to return
to the coast tonight into early Sunday morning before retreating to
the coastline by early afternoon. As such, overnight low
temperatures are forecast to range from the mid 50s to lower 60 in
the valleys and mid 60s to lower 70s in the higher terrain.
For Sunday, expecting upper 80s to lower 90s across the interior,
mid 70s to lower 80s around the bayshore and around the Santa Cruz
area, and upper 60s to lower 70s near the coast.
&&
.LONG TERM...
Issued at 141 PM PDT Sat Sep 20 2025
(Sunday night through next Friday)
The warming of afternoon temperatures will continue into Monday (and
potentially into Tuesday) when we are expecting more widespread
upper 80s to mid 90s across the interior. Generally the same
aforementioned mid/upper level features will persist before the cut off
low begins to near the coast Monday night into Tuesday. There is
moderate confidence that the higher terrain will experience offshore
flow (especially across the North Bay and East Bay interior) during
this timeframe.
Sub-tropical and/or monsoonal moisture will be advected northward as
the cut off mid/upper level low pressure nears the coast brining the
potential for rain showers and isolated thunderstorms to the Central
Coast on Tuesday. The increased cloud cover is expected to keep the
Central Coast cooler on Tuesday with warmer conditions across the
north and in the interior. With PWAT values between 1.00"-1.50" and
MUCAPE values between 100-300 J/kg expected, the treat for dry
lightning will be limited. The potential for rain showers will
extend northward into the North Bay by Tuesday night into Wednesday
morning before the the low pressure shifts inland into Nevada.
Dry conditions are anticipated by Thursday in wake of the exiting
cut off low. A gradual cooling trend is then expected late in the
upcoming week and into the next weekend as a trough approaches the
West Coast. Be sure to keep up to date on the latest forecast
information as we get closer to this upcoming pattern shift.
&&
.AVIATION...
(18Z TAFS)
Issued at 1108 AM PDT Sat Sep 20 2025
Solar energy dissipated mid level clouds and continues to dissipate
lingering coastal stratus and fog. A few areas are still reporting
MVFR ceilings due to stratus, otherwise it`s VFR at the terminals.
VFR will prevail during the afternoon at the terminals. During the
evening and overnight coastal as well as patchy valley stratus and
fog /IFR-LIFR/ will redevelop per HREF. Mainly onshore winds during
the 12z TAFs.
Vicinity of SFO...VFR today and this evening, tempo BKN ceiling
developing 10z-13z Sunday, prevailing MVFR ceiling until 1730z
Sunday. West to northwest wind 5 to 10 knots except 15 to 23 knots
this afternoon and evening.
SFO Bridge Approach...Similar to SFO.
Monterey Bay Terminals...VFR today and likely continuing into early
this evening, since we already have a strong start to September sun
i.e. diurnal surface warming and mixing this morning. Tempo stratus
/IFR/ ceilings mid to late this evening then IFR prevailing overnight
into Sunday morning. VFR returning late Sunday morning. Onshore winds
5 to 15 knots except light and variable tonight and Sunday morning.
&&
.MARINE...
(Today through Thursday)
Issued at 1056 AM PDT Sat Sep 20 2025
Winds stay mostly light across the waters aside from locally
breezy conditions near the favored coastal jets. Winds begin to
increase in the northern waters into Sunday afternoon. These
winds spread across the coastal waters into the work week with
locally near gale force gusts across the northern outer waters.
Winds decrease to moderate to fresh across the coastal waters
Tuesday through late week.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory from 3 PM Sunday to 3 AM PDT Monday for Pt
     Arena to Pt Reyes 0-10 nm.
Small Craft Advisory from 3 PM Sunday to 9 AM PDT Monday for Pt
     Arena to Pt Reyes 10-60 NM.
&&
$$
SHORT TERM...RGass
LONG TERM....RGass
AVIATION...Canepa
MARINE...Canepa
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NWS MTR Office Area Forecast Discussion