Pleasanton, California Weather Forecast Discussion

686
FXUS66 KMTR 092021
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
121 PM PDT Tue Sep 9 2025
...New SHORT TERM, LONG TERM...
.KEY MESSAGES...
Updated at 120 PM PDT Tue Sep 9 2025
- Slight (15-25%) chance for thunderstorms in the North Bay during
   the afternoons through Thursday
- Temperatures below seasonal averages and chances for showers
   continue through Thursday
- Warming on Friday and Saturday before another front arrives
   Sunday
&&
.SHORT TERM...
Issued at 120 PM PDT Tue Sep 9 2025
(This evening through Wednesday)
Radar returns are showing isolated showers lingering in some parts
of the Bay Area and Central Coast, with a blob of showers setting up
around 100-200 miles to the west of San Francisco. The chance for
isolated to scattered showers, some of them relatively intense,
continues through the day and into the overnight hours, with
convective probabilities focused on the northern regions of Sonoma
and Napa counties. Probabilities for thunderstorms in the area reach
10-15% this afternoon and evening, with the chances for convection
decreasing as you go southward through the Bay Area. Should
convective showers develop, accumulations could reach a quarter of
an inch, with gusty winds and lightning being the other key hazards.
Outside of thunderstorms, the rain will generally be beneficial,
with accumulations up to one tenth of an inch of rain. Remember:
When thunder roars, go indoors! Or, see a flash, dash inside!
The chance for showers continues into Wednesday, as the deepening of
the upper level low bottoms out, creating rather elevated chances
(15-25% probability) for convective activity in the North Bay during
the afternoon and evening.
High temperatures today and Wednesday will range from the 70s inland
to the middle to upper 60s along the Pacific coast, with lows in the
middle 50s to the middle 60s across the lower elevations. With fresh
rainfall in the region, patchy dense fog is possible in the coastal
regions and cooler valleys. If you encounter patchy fog while
driving, slow down and use low-beam headlights.
&&
.LONG TERM...
Issued at 120 PM PDT Tue Sep 9 2025
(Wednesday night through next Monday)
The chances for showers and thunderstorms will diminish on Thursday,
as the upper level low weakens and crawls eastward, but the current
forecast has chances remaining non-zero throughout the Bay Area. As
the upper level low passes, a brief period of ridging settles in for
Friday and Saturday, with the inland valleys reaching the upper 70s
to the middle 80s, before Sunday brings another cold front and
another chance of rain.
&&
.AVIATION...
(18Z TAFS)
Issued at 1208 PM PDT Tue Sep 9 2025
The front has passed, leaving us with mainly VFR to MVFR conditions
and lingering showers. These conditions will likely continue over
the TAF cycle, with perhaps drier conditions for the afternoon and
evening hours. The latest model guidance shows chances for showers
increasing tomorrow morning, near or just after sunrise. Adjusted
the forecast towards that outlook, carrying either VCSH or -SHRA.
Thunder chances remain negligible  for the TAF sites and confidence was
too low to add VCTS.
Vicinity of SFO...Mainly VFR conditions should prevail until later
this evening, when low clouds make a return. Showers may skirt by
the airspace over the next couple of hours, with dry conditions
expected through the overnight hours. Given the timing change for
rain, opted to keep the mention of -SHRA towards mid to late
Wednesday morning. Confidence is medium to low on precipitation
timing, and medium on CIGs tonight.
SFO Bridge Approach...Similar to SFO.
Monterey Bay Terminals...Mainly VFR conditions should prevail this
afternoon unless some rogue showers sneak by, which may bring brief
periods of MVFR conditions. Come the evening, we should see a return
of MVFR to IFR CIGs with showers potentially arriving around or
after sunrise. Medium confidence in the CIG forecast, low to medium
confidence in the precip timing.
&&
.MARINE...
(Today through Sunday)
Issued at 905 AM PDT Tue Sep 9 2025
Scattered light rain showers are expected across the coastal
waters  through Thursday as an upper level low moves into the West
Coast. Isolated thunderstorms are possible during the afternoons
Tuesday through Thursday. Thunderstorm chances peak on Tuesday
across the northern coastal waters. A gentle to moderate breeze
will  continue Tuesday with a moderate to fresh breeze developing
over  the outer waters Wednesday into the weekend.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...None.
&&
$$
SHORT TERM...DialH
LONG TERM....DialH
AVIATION...KR
MARINE...KR
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NWS MTR Office Area Forecast Discussion