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NWS Technical
Weather Discussion |
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FXUS66 KMTR 260529
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
929 PM PST Sun Jan 25 2026
...New AVIATION, MARINE...
.KEY MESSAGES...
Updated at 1210 PM PST Sun Jan 25 2026
- Weak offshore winds prevail; remain light into mid-week
- Slight chance of rain showers overnight Tuesday into Wednesday
morning. Amounts generally less than 0.1" and focused in the
North Bay.
- Dry to end the rest of the week; next chance of rain after the
1st, but low confidence as of now
&&
.UPDATE...
Issued at 841 PM PST Sun Jan 25 2026
Satellite imagery shows mid- to high level cloud cover moving
through the region, and starting to exit parts of the North Bay.
The short-term forecast remains generally on track, with some of
the higher resolution models noting a slight chance for showers
across the coastal waters beginning in the pre-dawn hours of
Monday morning. Most of the high resolution models are not going
far enough in time to capture the rain event later on Tuesday into
Wednesday, but the couple that do are trending towards the wetter
side for the North Bay coastal ranges. The latest runs of the
PG&E WRF model and the experimental RRFS are showing the
possibility for rain totals of around 0.1-0.3" in the Sonoma
County coastal ranges. This is a little higher than what previous
runs of those models were showing, so it will be interesting to
see if the trend towards slightly wetter conditions continues
through Monday, particularly as the HRRR and the 3 km NAM start to
capture the event.
DialH
&&
.SHORT TERM...
Issued at 1210 PM PST Sun Jan 25 2026
(This evening through Monday)
Another cloud-filled, mixed-sky day as upper level moisture
advances ahead of a weak upper level shortwave trough currently
off the coast of Mendocino/Humboldt county. Current radar is
picking up on some echos aloft, but there are not expected to make
it to the ground as rain, especially the massive block of dry air
in the mid-levels up to about 23 kft. One thing this might
actually bring us that you'll want to pay attention to is a
wonderful sunset this evening, if you're in an area without low
clouds.
&&
.LONG TERM...
Issued at 1210 PM PST Sun Jan 25 2026
(Monday night through next Saturday)
A couple more chilly nights ahead before another approaching
shortwave trough promotes moist, southerly flow, which will bring
temps up a few degrees for overnight lows and afternoon highs.
This shortwave brings the only confident chance for measurable
rain within the 7 day forecast, and amounts have been trending
lower with each issuance. By late Tuesday, a 120 kt jet streak
downstream of the trough axis becomes the driving force to lift
the system towards the north. This likely thwarts any meaningful
rain chances across much of our region. As of now, it looks like
the North Bay counties are the only areas that would get anything
worth mentioning (0.05-0.10"), and elsewhere may only see as much
as a hundredth or two. Most of this looks to take place Wednesday
morning. After that, ensemble cluster analysis exhibits high
confidence that the rest of the week will remain dry. The next
chance of rain doesn't enter the picture until the 1st of February
where a deeper upper level trough may swing through the EPac, but
uncertainty is high in N-S placement. As such, there is not much
confidence in early Feb rain at this point.
&&
.AVIATION...
(06Z TAFS)
Issued at 923 PM PST Sun Jan 25 2026
For the 06Z tafs fog arrived a little earlier for KSTS than
previously forecast. Will keep MVFR with IFR developing later for
KSTS. Otherwise, elsewhere mainly VFR through the night and early
Monday. We'll see a weak boundary approach late in the taf period
which will lower some cigs and have winds becoming more
southerly.
Vicinity of SFO...VFR with an offshore flow.
SFO Bridge Approach...Similar to SFO.
Monterey Bay Terminals...VFR. Breezy drainage flow for SNS Monday.
Low chc (less than 20%) of MVFR cigs creeping into MRY by the end
of the taf on Monday.
&&
.MARINE...
(Tonight through next Saturday)
Issued at 923 PM PST Sun Jan 25 2026
Gentle to moderate southerly breezes will continue through early
Monday. Winds will be strongest north of Point Reyes. Winds
diminish and switch to northerly on Wednesday. Moderate seas will
prevail through Tuesday. Conditions deteriorate Wednesday as seas
build to become rough to very rough. Additionally, a weak passing
storm system will bring light rain to the coastal waters Monday
through Wednesday.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...None.
&&
$$
SHORT TERM...Behringer
LONG TERM....Behringer
AVIATION...MM
MARINE...MM
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Prepared by Boulder-Creek.com Weather at: Mon Jan 26 00:30:03 PST 2026
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Revised:
29 Mar 2008 09:53 -0800 GMT
(Pacific) |
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