Bloomfield, California Weather Forecast Discussion

072
FXUS66 KMTR 210458
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
958 PM PDT Sat Sep 20 2025
...New AVIATION...
.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
&&
.UPDATE...
Issued at 830 PM PDT Sat Sep 20 2025
Skies are clear across the region with stratus beginning to move
into the area from the north. The warming and drying trend will
continue tomorrow with temperatures near to slightly above normal
for the interior and temperatures slightly below normal at the
coast. If you are spending time outside tomorrow: increase
hydration, wear sunscreen, and seek shade during the warmest part
of the day.
Sarment
&&
.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...
(06Z TAFS)
Issued at 958 PM PDT Sat Sep 20 2025
Models are continuing to overdo the amount of stratus along our
coastline which is resulting in guidance showing stratus returning
far too early tonight. Pushed stratus arrival back closer to 09-12Z
based on a combination of NAMNest (handling offshore stratus best)
and HRRR guidance. If the NAMNest continues to perform the best, it
indicates a possibility for most sites across the Bay Area to stay
clear overnight. Stratus will be on the MVFR-IFR border tonight with
some potential for LIFR and fog along the coast and North Bay
Valleys. Clearing remains on track for mid to late morning with VFR
through the rest of the TAF period.
Vicinity of SFO...MVFR expected early tomorrow morning before VFR
returns through the remainder of the TAF period. Low to moderate
confidence that MVFR CIGs will reach SFO early tomorrow morning. The
NAMNest is handling the lack of offshore stratus the best. If this
continues to hold true, it suggests that stratus will not reach SFO
tonight. Confidence is low that stratus will not fill in overnight
at SFO so kept a brief period of stratus in from 12-18Z. Conditions
improve by mid to late morning with gusts peaking around 25 knots
this afternoon/evening.
SFO Bridge Approach...Similar to SFO.
Monterey Bay Terminals...VFR becoming IFR overnight. Satellite shows
stratus filling in on the Monterey Peninsula which increases
confidence that MRY will start seeing stratus shortly. Initial
stratus may be patchy at MRY and SNS but is expected to fill in and
become more permanent by 09-10Z. There is a low chance for fog along
the coastline. However, given that the marine layer is above 1000 ft
on the Fort Ord profiler I leaned more towards stratus and less
towards fog overnight at MRY and SNS. Conditions improve by late
morning with winds becoming more moderate in the afternoon.
&&
.MARINE...
(Tonight through next Friday)
Issued at 830 PM PDT Sat Sep 20 2025
A gentle to moderate northwest breeze continues through Sunday
morning. Winds increase to fresh to strong and wave heights build
across the coastal waters late Sunday through early next week as a
cutoff low moves into California. There is a low chance for
isolated showers and embedded thunderstorms Tuesday into Wednesday
across the southernmost waters. Winds decrease and seas abate
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...Kennedy
MARINE...Kennedy
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NWS MTR Office Area Forecast Discussion