wxsniss

18z AI-GFS (I have no idea if this is worth anything) is also ticking better than 12z

If there's any takeaway from 18z suite, it's that this is not continuing to slip away into nothing (which was a distinct possibility on yesterday's guidance). It will be meager, but there will be accumulation.

On this 18z NAM: some decent fronto scrapes the south coast... could see upwards of 3-5" right at the water if that occurs. Let's hold or continue these ticks in the next 12 hours...

1 hour ago, TauntonBlizzard2013 said:

This is the exact type of event that we’d get to go from what it is now into a low end warning in the mid 2010s. Haven’t had any such luck recently. There is a path to a solid advisory, no matter how small it is 

Yeah it's been a tough stretch for the region and this hobby.

I posted last night... I remember the forum days of all-hands-on-deck war-room analysis for an impending KU, and now I'm micro-dissecting 1-2" vs. 2-3". We're famished for a region-wide larger event. Dec 20 2024 was the last positive bust for MBY (Boston suburbs) in years, and it was ~5.5".

But easy to forget (maybe because the unseasonal cold) that it's very early and there's lots of winter to go.

Box update

As noted above, upside potential at this point IF the vort comes in stronger, could add 1-2" south and east zones, with maybe spots 4-5" total in outer Cape... 

18 minutes ago, weathafella said:

Honestly if that actually turns out to be the case Skynet should do better in subsequent similar setups.

Do you know how often the AIFS is re-trained? Would be amazing if in fact it gets better over the course of each event and each idiosyncratic setup.

I came across this indicating an updated training schedule, but does not detail: https://arxiv.org/abs/2509.18994

(before I get misconstrued... I would hate losing the joy and suspense of forecasting to a perfect AI)

Brace yourselves...

Let's at least get some Foxboro snow mojo in the air Sunday

2 hours ago, TauntonBlizzard2013 said:

Once again, we added another negative variable over the last 24+ hours. Not only is it still not turning the corner, it’s kind of lost its potency so even on some of those earlier runs without much coastal involvement we were getting a couple inches.

Now, over the last several cycles, that has kind of disappeared 

18z NAM was an example... on that run, more energy was able to compensate a little for the worse tilt and southeast squash

To echo what CoastalWx and others have said... I remember the occasions, felt like a few times every season, when we were micro-analyzing such details with huge stakes on the eve of classic KUs. Now the stakes are a few inches and it's tiring.

0z Euro continued to tick the trough more positive and outcome more southeast... maybe 1-3" south coast, 3-4" outer Cape. 0z AIFS a hair better.

Not liking NAM trend at 18z, fwiw...

18z Saturday/0z Sunday is a key litmus I've been using on all guidance... all about pin-the-PV-center-on-the-lake... the further northwest that lobe center is, the better the downstream heights and tilt of our trough for our storm a day later: Over Lake Superior, high-end advisory. East of Lake Huron, it's a scraper.

Maybe the most negative steady trend today is both Euro-AIFS and EPS incrementally pulling away for 4 cycles since 6z today

0z EC: can see the worse outcome well before... at 72h 0z Sunday the PV center ticked slightly east over Lake Huron instead of Lake Michigan... that slight tick is enough to smush heights downstream and keep the trough more positive... 

Models are vacillating between SNE graze vs. 1-3/2-5... (and though hard to explain, it does strangely seem to correlate with 6z/18z vs. 0z/12z). Probably won't lock in for another 24 hours or so. I'm still favoring at least advisory in southeast areas.

Definitely better tilt, orientation of TPV, and upstream ridging by 0z Sunday compared to EC 0z... at moment a light event for southeast areas, but just minor tweaks will get significant improvement at surface on future runs

vs. 6z, EC significantly improved western ridge, not sure energy will dig and tilt enough to deliver on this specific run, but 14th a definite contender

29 minutes ago, weathafella said:

It was a nice snow burst whitening the ground earlier but now a memory.

Always a thrill to see opening best rates of the season, though only for about 3 minutes… 

We’ll have our chances… this alone looks like it should bring much better results at surface than it actually has, and can tweak significantly better with time:

Messenger's back yard (may he RIP) in Plymouth must be pushing 8" at this point

That coastal front / area of convergence has been nearly stationary for >24 hours

Let's repeat late January

9 minutes ago, powderfreak said:

Love how much of the discussion revolves around imaging this in winter and how elated or upset folks would be.

Some things never change.  Winter still rules the forum.

Was just thinking same and logged in to get the feel, watching this ongoing firehose into south shore. Let's repeat in late January.

This secondary line pushing into Boston metro and southshore is more impressive... very heavy downpours, CG

Says both radar-confirmed and OTG...

812 
WWUS51 KBOX 062008
SVSBOX

Severe Weather Statement
National Weather Service Boston/Norton MA
408 PM EDT Sat Sep 6 2025

MAC017-027-062045-
/O.CON.KBOX.TO.W.0003.000000T0000Z-250906T2045Z/
Worcester MA-Middlesex MA-
408 PM EDT Sat Sep 6 2025

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 445 PM EDT FOR EAST
CENTRAL WORCESTER AND CENTRAL MIDDLESEX COUNTIES...

At 407 PM EDT, a confirmed tornado was located over Holden, or near
Worcester, moving east at 40 mph.

HAZARD...Damaging tornado and quarter size hail.

SOURCE...Radar confirmed tornado.

IMPACT...Flying debris will be dangerous to those caught without 
         shelter. Mobile homes will be damaged or destroyed. Damage 
         to roofs, windows, and vehicles will occur.  Tree damage is 
         likely.

This tornado will be near...
  Worcester, Marlborough, Shrewsbury, Hudson, Westborough, Holden, 
  Northborough, Clinton, Lancaster, and Sterling around 415 PM EDT.
  Southborough, Stow, and Harvard around 420 PM EDT.
  Framingham, Acton, Sudbury, Maynard, and Boxborough around 425 PM 
  EDT.
  Littleton around 430 PM EDT.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

To repeat, a tornado is on the ground. TAKE COVER NOW! Move to a
basement or an interior room on the lowest floor of a sturdy
building. Avoid windows. If you are outdoors, in a mobile home, or in
a vehicle, move to the closest substantial shelter and protect
yourself from flying debris.

Torrential rainfall is occurring with this storm, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

&&

LAT...LON 4223 7187 4241 7195 4252 7150 4230 7143
TIME...MOT...LOC 2007Z 251DEG 34KT 4234 7186 

TORNADO...OBSERVED
MAX HAIL SIZE...1.00 IN

$$

4 hours ago, kdxken said:

So many great photos from yesterday. Most photogenic day of the year? 

 

100%
 

Incredible sunset colors backlighting towering CB with frequent crystal clear lightning, and otherwise clear dark blue sky… amazing I wish I could capture better 

My wife was yelling at me for wasting ice cream as I was frantically taking photos

Another beaut… moonrise at Hampton Beach this weekend:

Man photos don’t do this justice and I wasn’t able to catch the best…

Spectacular lightning with sunset colors

16 minutes ago, CoastalWx said:

Massive CG strike.  Heavy heavy rain.

Extremely heavy here for a few minutes

Back side looking from Coolidge Corner, with clear blue following it…

A hint of a rainbow too:

Let’s hope this isn’t true…

https://studyfinds.org/winter-weather-moving-west-how-the-polar-vortex-rewriting-americas-cold-map/

“LOWELL, Mass. — Americans expecting the worst winter weather to slam the East Coast might need to look northwest instead. A major study spanning four decades reveals that severe winter storms are shifting away from traditional snow belt regions toward the Pacific Northwest and northern Rockies, potentially changing where Americans should brace for brutal cold and heavy snow…”

”According to the study, published in Science Advances, the first pattern “features an upper-level vortex displaced toward western Canada and linked to northwestern U.S. severe winter weather.” The second “features a weakened upper-level vortex displaced toward the North Atlantic and linked to central-eastern U.S. severe winter weather.”

Amazing feed, just keeps going into Boston metro... another rumble heard at 12:30am looks near Hingham

Thunder in Fenway area

This is really impressive

LLJ taking its time lifting north

Heaviest of day right now, hoping we hear some thunder

Love the activity in here… if only this was January