DAYS 1-5 (FEBRUARY 20-24)
The next weather event in our active pattern stares us in the face this morning and while some areas saw a colorful sunrise, an overcast day is ahead. As approaching low pressure nudges a frontal boundary northward toward our area, the precipitation shield it generates will overspread the region starting by midday. With borderline temperatures in place we can see it start as rain or a mix the closer to the coast and further south you are, and snow to the northwest, and the snow should be dominant at first, but warmer air moving in at mid levels eventually means more mixing and rain, especially south of the Route 2 corridor, and this will limit or even prevent accumulation of any snow / sleet the further south you go. Yesterday’s forecast ranges remain in place for this update, but I am leaning toward the lower ends of them. This will include some additional minor accumulation as the low pressure area redevelops along the front that never quite makes it through the region, and pulls slightly colder air back to the south later tonight into Saturday, when some lingering light snow and snow showers can occur not only during the day, but even into the evening. These accumulations, stretched out over 24 hours, while not impressive, will be even less so in real time since they occur not on a quick burst, but over a longer time period. Expectations: Coating to 1 inch I-90 southward except 1-2 inches higher elevations south central MA and adjacent northwestern RI and northeastern CT, 1-3 inches Route 2 corridor northward except 3-5 inches higher elevations far north central MA and interior southern NH (again leaning toward lower ends of these ranges). I continue to monitor guidance and synoptic set-up regarding the system that follows this, discussed at length this week, and repeated here by saying there is pretty much no change to the ideas, as I continue to lean toward a quicker-moving, slower-developing low pressure area along the Mid Atlantic Coast that eventually starts to intensify more rapidly as it tracks northeastward, passing a fair distance southeast of New England late Sunday to early Monday. By then it will be cold enough that we only talk about a snow shield associated with it (no mixing). The storm is expected to be far enough offshore so that its main snow shield has the most significant impact on southeastern MA, especially Cape Cod and the Islands, while a lighter snowfall takes place elsewhere due to the interaction of this system with upper level low pressure still having to cross the region, with the “maximum” precipitation period Sunday evening before it departs on Monday. The wake of the system presents us with dry and seasonably chilly conditions for the balance of Monday through Tuesday.
TODAY: Cloudy. Snow/mix/rain arrives midday-afternoon. Highs 35-42. Wind variable to NE up to 10 MPH.
TONIGHT: Cloudy with mix/snow tapering to snow showers. Lows 27-34. Wind NE to N 5-15 MPH.
SATURDAY: Mostly cloudy with occasional snow showers. Highs 33-40. Wind N 5-15 MPH.
SATURDAY NIGHT: Partly cloudy. Lows 23-30. Wind N under 10 MPH.
SUNDAY / SUNDAY NIGHT: Cloudy. Afternoon snow develops, favoring southeastern areas / Cape Cod. Highs 30-37. Lows 23-30. Wind NE 5-15 MPH except 15-25 MPH Cape Cod with higher gusts.
MONDAY: Clouds break for sun. A few snow showers possible favoring eastern areas. Highs 30-37. Wind N 10-20 MPH except 20-30 MPH far eastern areas, with higher gusts, diminishing late.
MONDAY NIGHT / TUESDAY: Partly cloudy. Lows 16-23. Highs 31-38. Wind N to NW 5-15 MPH.
DAYS 6-10 (FEBRUARY 25 – MARCH 1)
Watching for additional unsettled weather in the February 25-27 time frame and again as March arrives. Temperatures near to below normal.
DAYS 11-15 (MARCH 2-6)
Unsettled potentials start and end the period with fair weather between the two chances. Temperatures near to below normal.
Thanks!
First?
Wordle 4
Awesome
Thanks TK
Good morning and thank you TK
30 here after low of 27
Ocean: 36
Wordle: 6 Thought I had it in 3, nope didn’t like the word, but had 1st 4 letters in correct position. Didn’t like word 4. Didn’t like word5 and FINALLY accepted word 6
Iโll be joining you again. In the PHEW car. Would you like muffins or danish?
It was the fifth letter that I couldnโt get either. Had 1,2,3,6 with guess 3
6Z EURO AI total snow after Monday system:
https://www.pivotalweather.com/model.php?m=ecmwf_aifs&p=sn10_024h-imp&rh=2026022006&fh=108&r=us_ne&dpdt=&mc=
This includes about 3 for today, so about 6 inches for Boston, More SE.
6Z Euro, best 24 hour precip for Monday and Best surface.
https://ibb.co/k6gbkrdh
https://ibb.co/gL3Fr69n
My Hobbist,non-professional thoughts on the Monday system:
1. It is coming, May not be a direct hit, but enough of one to notice. Moderate snow storm with possibly more.
2. GFS lead the way and now joined by GFS AI, GDPS, RDPS, EURO, AURO AI and to a lesser extent event the ICON
RRFSA joins the UKMET in saying NOPE!
The GFS is not “leading” anything, except the clown show. ๐
Tell us how you really feel about the GFS, ๐ ๐ ๐
After the DISMAL performance the other day, I kind of feel that way about ALL of them. ๐
Oh I have. Many times. I just hope they fix it … eventually, or as Gordon Ramsay says: “Shut it down!”
As we always say, GFS is โgood for s***โ – now is that four letter word snow? Iโll let you be the judge.
The 0Z GDPS is an outlier for today’s event, but I am going to post this anyway.
Kuchera snow for today-tomorrow snow
https://www.pivotalweather.com/model.php?m=gdps&p=snku_acc-imp&rh=2026022000&fh=66&r=us_ne&dpdt=&mc=
Too bad the majority of measurable precipitation falls as sleet & rain in the bulk of the area on this one, otherwise the GDPS “might have been onto something”. ๐
NWS snow map for today
https://www.weather.gov/images/box/winter/StormTotalSnow.jpg
Better than the last edition, and even better than the edition before that, but they might want to run the trimmer over that one more time.
Jeremy Reiner on the Greg Hill Show just now talked about recent warts on the Euro model and when pushed on totals for Monday said โMy manager is going to kill me because we donโt have a map out yet but a chance of a foot in Bostonโ
Chance of a foot, eh? We shall see. Going to be fun the next few days!!!
Someone at work told me shiri spear just recently talked about a chance of a foot but on her broadcast so it seems to be going around.
Thanks TK. If I am reading correctly this early, neither storm seems like the end of the free world
Correct.
12Z HRRR Kuchera Snow for today/tomorrow
https://www.pivotalweather.com/model.php?m=hrrr&p=snku_acc-imp&rh=2026022012&fh=22&r=us_ne&dpdt=&mc=
This seems more in line.
Thanks TK !
Wordle: 5
Nice.
Very nice
Thanks TK.
Going to be an interesting 24 hrs. I am curious 12z and especially 9z tonight as then we see within 48 hr of onset.
Indeed it is!
Just curious what are you thinking we get out of this ?
To Hadi
Thanks, TK.
Despite winter still being in control, wildlife instinctively knows changes are happening. I’ve noticed a distinct increase in bird activity and chirping in the past 10 days. Not to spring levels, but still.
The amount of daylight is the primary driver.
Indeed.
In the spirit of no such thing as a dumb questรฌon. What is kuchera snow? Also, doesnโt a foot in Boston seem high unless things really take a turn?
Kuchera snow model is just a simple way to portray how much snow to fallโฆ a 10:1 ratio for example which is what you usually see with models is ten inches of snow per one inch of precip.
To add to this even though jpdave did betterโฆ
To add to this – this is why for some storms like the one that gave us two feet youโll see people like TK say โthis could actually be 15:1โ or other numbers.
As for if a foot seems really high for the monday storm unless things take a turn – the forecasters are basically saying that a simple turn of the models showing the track being even fifty miles more west could mean a more impactful hit. This is under the auspices of โanything can happenโ since weโre still four days removed but the cynic in me thinks thereโs always a bit of flash programmed into them for the tv ratings aspect. Now that Iโve said that watch us get a blizzardโฆ because technically anything is possible which is why NWS always has a 1 in 10 chance map they generate for each storm.
Things would have to go just right (or wrong depending on perspective) for Boston to get a foot. We shall see.
Opinions vary, even with professional meteorologists.
Kuchera takes into account temperature, humidity etc profiles at various altitudes in an attempt to determine how much snow per inch of rpecipitation. It is not perfect, but Better than just using 10:1.
The Kuchera method is a, snowfall-forecasting technique developed by U.S. Air Force meteorologist Evan Kuchera to estimate snow-to-liquid ratios (SLR) more accurately than the standard, often inaccurate, fixed 10:1 ratio. It is a “dynamic” method that adjusts the snow ratio based on temperature, typically resulting in higher, more realistic snowfall totals for cold events
The HRRR and the RRFSA have their own ratio algorithms built into the models, so it is Neither Kuchera nor 10:1.
FWIW, 12Z NAM kuchera snow for today/tomorrow
https://www.pivotalweather.com/model.php?m=nam&p=snku_acc-imp&rh=2026022012&fh=27&r=us_ne&dpdt=&mc=
12Z HRW FV3 Kuchera Snow for today/tomorrow
https://www.pivotalweather.com/model.php?m=hrwfv3&p=snku_acc-imp&rh=2026022012&fh=27&r=us_ne&dpdt=&mc=
12Z 3KM NAM Kuchera snow for today/.tomorrow
https://www.pivotalweather.com/model.php?m=nam4km&p=snku_acc-imp&rh=2026022012&fh=32&r=us_ne&dpdt=&mc=
Iโm so glad we are basically missing out on a potential significant snowstorm late Sunday and Monday.
Donโt count your chickens before they hatch lol
Who says we are missing out. we may, but we may not.
Please stay tuned.
FYI: This is the first event in a while where the “snow depth change” map is going to be of some value when looking at model output, not just the straight up Kuchera representation.
ASSUMING correct model output, the snow amount would be somewhere between those 2.
Shiri just said (I was watching the live broadcast) โI canโt tell you if Boston is going to get four or fourteen inches of snow. It all depends on the track.โ Verbatim quote.
She showed this image: https://ibb.co/zh7Hs51b
Love her, but Imma nudge that map a bit to the southeast.
Iโd agree. I also think that these meteorologists know that most people are only going to hear her say โfourteenโ which will just cause them headaches on social media lol
Similar graphic Danielle and Matt just posted on their 1degrees site.
Now lets get crazy.
Here is the 6Z GFS for the Monday System.
Surface
https://www.pivotalweather.com/model.php?m=gfs&p=prateptype_cat-imp&rh=2026022006&fh=81&r=us_ne&dpdt=&mc=
24 hour Kuchera snow (fyi it repots ratio of 13:1)
https://www.pivotalweather.com/model.php?m=gfs&p=snku_024h-imp&rh=2026022006&fh=90&r=us_ne&dpdt=&mc=
the GFS has not backed down, has NOT read the memo, Doesn’t give a crap about what people say. It just does its thing. Will it be correct? who knows. ๐ ๐ ๐
Please don’t shoot the messenger. Just posting what this particular model has to say.
Saw that run. Had to chuckle.
This is the 4th or 5th threat of significant storminess that the GFS “has not backed down” (a phrase I never use myself, because I loathe it with regard to models – it makes it sound like they have conscious choice), only to “back down” at the last minute. We’ll see if this is the 5th or 6th. ๐
Yes, we shall see. ๐ ๐
I am watching.
REALLY waiting on today’s 12Z Euro run.
For more drama, here is the GFS total kuchera snow for both today and Monday system, Deduct “about” 4 inches for today to get the Monday system final total which would be 18-20 inches for Boston
https://www.pivotalweather.com/model.php?m=gfs&p=snku_acc-imp&rh=2026022006&fh=120&r=us_ne&dpdt=&mc=
The fact these models are putting out 4โ for todayโs event should tell u they might be wrong about sun/mon
Agree that most of this area seems to be projected low end of 1-3. If they canโt hit the short putt, can you trust them to make the 40 footer?
This morning had the second great sunrise in a row.
Also, I got the second 5 for Wordle in a row!
You beat me!!! ๐
Thank you, TK. Up to 31 from a low of 24
https://www.pivotalweather.com/model.php?m=ecmwf_full&p=850wh&rh=2026022000&fh=84&r=us_ne&dpdt=&mc=
https://www.pivotalweather.com/model.php?m=gfs&p=850wh&rh=2026022000&fh=84&r=us_ne&dpdt=&mc=
https://www.pivotalweather.com/model.php?m=gdps&p=850wh&rh=2026022000&fh=84&r=us_ne&dpdt=&mc=
https://www.pivotalweather.com/model.php?m=icon&p=850wh&rh=2026022000&fh=84&r=us_ne&dpdt=&mc=
I was mentally thinking back to the system a week or 2 ago that gave Myrtle Beach several inches of snow. Much different set up here, even though they both are east coast systems.
Anyhow, hereโs 850 mb map projected winds from the 00z suite, 84 hrs out.
All I deduce from this is, thatโs a decent low level jet off the ocean for at least a few hrs anyway.
Which could translate to SNOW. ๐ How much is the question.
Welcome back bud
12Z NAM is not interested….
https://www.pivotalweather.com/model.php?m=nam&p=ref1km_ptype&rh=2026022006&fh=84&r=conus&dpdt=&mc=
But that is the NAM and also at 84 hours. ๐
Wordle in 6 in the most annoying way possible because even though I thought of the right word when looking for a third guess I figured โno way theyโd ever use this word. Has to be something else.โ https://ibb.co/NdJdkJ5g
I had a similar result. But you know you have a way the answer for those who have not yet played. ๐
Please join me in the CABOOSE!!!
Exactly my thought process. Happy to have you joining JPD and me in the caboose.
12Z ICON has come even farther N&W
12z
https://www.pivotalweather.com/model.php?rh=2026022012&fh=78&dpdt=&mc=&r=us_ne&p=prateptype_cat_icon-imp&m=icon
6Z
https://www.pivotalweather.com/model.php?rh=2026022006&fh=84&dpdt=&mc=&r=us_ne&p=prateptype_cat_icon-imp&m=icon
12z 24 hour Kuchera Snow
https://www.pivotalweather.com/model.php?m=icon&p=snku_024h-imp&rh=2026022012&fh=96&r=us_ne&dpdt=&mc=
Total snow including “about” 2 inches for today
https://www.pivotalweather.com/model.php?m=icon&p=snku_acc-imp&rh=2026022012&fh=102&r=us_ne&dpdt=&mc=
“about” 18 inches for Boston!!!
Today’s 12z ICON is performing the same quasi-error that the GFS has been for numerous runs.
As somebody who pays close attention to model biases, I’ve seen the ICON do this inside 60 hours on several occasions.
12Z RDPS Kuchera snow for today
https://www.pivotalweather.com/model.php?m=rdps&p=snku_acc-imp&rh=2026022012&fh=45&r=us_ne&dpdt=&mc=
12Z RDPS total kuchera snow for today and Sunday/Monday
https://www.pivotalweather.com/model.php?m=rdps&p=snku_acc-imp&rh=2026022012&fh=84&r=us_ne&dpdt=&mc=
Deduct “about” 4 inches Boston for today’s snow
makes it about 8 inches for Boston on the Monday/Sunday system.
12Z RRFSA is also NOT INTERESTED in a snow storm for Sunday/Monday
https://www.pivotalweather.com/model.php?m=rrfs_a&p=ref1km_ptype&rh=2026022006&fh=78&r=conus&dpdt=&mc=
Would like to see this model come on board. The fact that it hasn’t gives me pause. We shall see.
Waiting on EURO!!!!
Page 2 headline in todayโs Boston Herald in BOLD print:
GET THE SHOVELS OUT!
Wonder who their met is????
12Z Kuchera snow for today
https://www.pivotalweather.com/model.php?rh=2026022012&fh=21&dpdt=&mc=&r=us_ne&p=snku_acc-imp&m=gfs
https://www.pivotalweather.com/model.php?m=gfs&p=500wh&rh=2026022012&fh=57&r=conus&dpdt=&mc=
I think the real meteorology question to be answered, is from here, what to the north of us impacts how the 500 mb tracks south of us.
Is there something up to our north at 500 mb that forces it more ENE or is there a little less of something that allows it to track more NE? I think thatโs the $64,000 question.
12Z GFS has ticked a bit to the East and is 6mb stronger
Will the stronger system throw snow back more West making up for the slightly more Eastward track?
12Z GFS 24 hour kuchera snow, pretty much covers the Sunday/Monday event
https://www.pivotalweather.com/model.php?m=gfs&p=snku_024h-imp&rh=2026022012&fh=84&r=us_ne&dpdt=&mc=
Surface
https://www.pivotalweather.com/model.php?m=gfs&p=prateptype_cat-imp&rh=2026022012&fh=72&r=us_ne&dpdt=&mc=
South Shore Jack Pot.
12Z GDPS
https://www.pivotalweather.com/model.php?m=gdps&p=prateptype-imp&rh=2026022012&fh=72&r=us_ne&dpdt=&mc=
24 hour kuchera snow
https://www.pivotalweather.com/model.php?m=gdps&p=snku_024h-imp&rh=2026022012&fh=84&r=us_ne&dpdt=&mc=
Next up, UKMET
Is this going to just be a case of which model blinks first to see where the snow goes or will other data eventually force the decision?
UKMET is tucked a little closer to the coast. Hmmm
Considerably so, Is the UKMET about to board the snow
train? I think, at least some.
And the UKMET has boarded. How long will it stay?
https://www.pivotalweather.com/model.php?rh=2026022012&fh=72&dpdt=&mc=&r=us_ne&p=prateptype_ukmo-imp&m=ukmo_global
UKMET total snow at 10:1, Deduct about 3 inches for boston for today’s snow
https://www.pivotalweather.com/model.php?m=ukmo_global&p=sn10_acc-imp&rh=2026022012&fh=90&r=us_ne&dpdt=&mc=
That would make “about” 9 inches at 10:1, but ratio is likely to be about 12 or 13 to 1.
About 11 inches for Boston and OVER 20 inches on the South Shore.
This model was previously OTS!!!
0Z version
https://www.pivotalweather.com/model.php?m=ukmo_global&p=prateptype_ukmo-imp&rh=2026022000&fh=87&r=us_ne&dpdt=&mc=
SOMETHING IS UP!!!
Found this for globe met
Lead Meteorologist: Ken Mahan, formerly with NBC News’ Climate Unit, focuses on covering New Englandโs diverse weather patterns, including nor’easters, snowstorms, and extreme temperatures.
Key Contributors: Dave Epstein, a meteorologist and horticulturist, provides expert insights for the publication.
Weather Editor: Marianne Mizera manages the weather desk.
The Globe & Herald used to rely on the company I worked for for their weather. That is when the newspaper page weather was actually good!
Now it’s data that’s usually gathered far too soon to be reliable, even though some of the sources are credible.
Looking at the radar one would think that it was snowing or raining pretty good. NOPE, NOTHING!!!!
Local radar
https://radar.weather.gov/station/KBOX/standard
37 here. NOT LIKING that for SNOW. ๐
Yes I mentioned that the snow #’s are too high.
I also mentioned the dry air that needs to be overcome. It’ll take the temps down a bit – but not that much.
Iโll be glad when Monday is over & this ridiculous hype is done
You talking about me? ๐
This is what we do here. Mark mus be tied up, so I am filling in for him. ๐
The hype is on social media, not here. We just discuss stuff. ๐
Exactly. And if you listen to any hype source on social media, thatโs on you
Huh? Why are you back to being like this? We discuss and analyze.
Hadi social media not here at all , all good here .
The fact that the GFS model is trying to give Boston over 5 inches of snow this afternoon should be TELL TALE.
Pam Gardener major winter storm probability
I have no control over what they say, and keep in mind a lot of what goes out on air is dictated by “the boss”.
I know , this is the exact hype that Iโm seeing itโs all over social media. Not here
Again. Donโt go there.
Thanks, TK!
12Z GFS AI
https://www.pivotalweather.com/model.php?m=aigfs&p=sfcwind_mslp&rh=2026022006&fh=84&r=conus&dpdt=&mc=
delivers 1.26 inch qpf to Boston
At 13 that would be about 16 inches of snow.
I personally don’t think it’s fair to compare snow output for this current storm and automatically apply it to Sun/Mon chance as they are very different set ups…meaning if somehow the sun/Mon storm does come close it doesn’t mean it won’t snow because fri/sat didn’t snow as much. I’m always rooting for snow so I hope it does but either way it’s been run to watch
I just do it the right way, as I was taught by my mentors and developed during my time as a professional. ๐
I know you are, but am definitely rooting for you to be wrong this go around!
Could happen! In fact I got a threatening phone call from the GFS this morning. ๐
(kidding of course – the GFS can’t really forecast the pattern very well, let alone make a phone call….) ๐
Euro AI is up next.
Here is an interesting video from Bernie Rayno.
TK you will NOT agree with him re: Posts on Social Media.
NICE discussion on storm possibilities. Not sure when this was posted. Looks like last night before the 0Z euro, but I am not sure.
Nice take regardless.
https://x.com/i/broadcasts/1AKEmOOwWpXKL
Good ole Bernie. ๐ His Accu-Weather bloopers are my favorite!
Thanks TK.
Probabilistic communication, when done properly, really is the key in a case like this. In some cases (yes, Iโm looking at the NWS) itโs gone too far with ridiculous โ0 to 20 inchesโ type maps 12 hours out from an event. But as a met there are ways to convey the possibilities without making it seem like you donโt know what youโre doing. Itโs a skill Iโve tried very hard to master, and itโs a constant learning process.
Is a BOS-DCA blizzard now the most likely scenario? I donโt think I would commit to that, but itโs a real possibility. But just like yesterday was too early to write it off OTS, I see some overconfidence on the high end solutions now.
This is also why itโs important to highlight the events, that have *high* predictability and build trust that way. If I were briefing decision makers, it would be really useful to draw a contrast between this less predictable event and the very high predictability storm a few weeks ago. Iโd be able to hopefully say โhey, the storm the other week was an easy one and I could tell you days in advance that big time snow was coming. This one is different because of โxyzโ and so we really donโt have as good a feel for it. But here are the reasonable possibilitiesโฆโ
Yes, sounds most reasonable. And what are you thoughts?
Yes? No? Maybe? maybe not? maybe so?
I would say 6โ+ in the BOS-PVD corridor and eastwards is a โmore likely than notโ outcome at this point. With potential for significantly higher amounts and major wind issues in a reasonable worst scenario, but also still a real chance of lesser amounts.
The other thing about these types of setups is that sometimes itโs โall or nothingโ, and sometimes itโs not. In other words, if you have models split between two vastly different camps, youโre not always well-served by splitting the difference. Sometimes the โmiddle groundโ is not a meteorologically reasonable outcome. I donโt see this as one of those times. An โin betweenโ solution is very possible here. And I think weโre starting to see a bit of that in the models with definitely westward moves on most of them but also at least a slight eastward nudge on the GFS.
Thank you WxWatcher. Interesting weekend, for SURE!
At Race Point Beach, took the walk down the dune to the beach. Of course, I had my sandals on and the tide was high, so I got my foot in the water.
Cold !!! But I did it ๐
WHY? that is the question I ask. You couldn’t pay me enough to do that!!! Well, I guess I would have a price. ๐ ๐
I’ve fallen through the ice on several occasions, so I do know what cold water feels like. ๐ ๐ ๐
Just starting to snow at Worcester. Visible on the Holy Cross Web Cam
Euro AI says 4 inches today at 10:1 which would likely mean 2 or 3 inches.
https://www.pivotalweather.com/model.php?m=ecmwf_aifs&p=sn10_acc-imp&rh=2026022012&fh=36&r=us_ne&dpdt=&mc=
12 EURO AI 24 hour 10:1 snow
https://www.pivotalweather.com/model.php?m=ecmwf_aifs&p=sn10_024h-imp&rh=2026022012&fh=84&r=us_ne&dpdt=&mc=
12Z EURO AI 10:1 total snow, including today
https://www.pivotalweather.com/model.php?m=ecmwf_aifs&p=sn10_acc-imp&rh=2026022012&fh=96&r=us_ne&dpdt=&mc=
Deduct “about” 4 inches for Boston
12Z Euro 10:1 snow
https://www.pivotalweather.com/model.php?m=ecmwf_full&p=sn10_acc-imp&rh=2026022012&fh=24&r=us_ne&dpdt=&mc=
WARNING!!! A crap load of sleet is included in that 10:1 snow.
Amount on ground would be considerably less than depicted, especially Boston South. Not only due to that, but also marginal boundary layer temps AND sun angle.
Winter storm watches up for the south coast and cape for sun/mon
Already? Wow!
Pretty strong wording
https://forecast.weather.gov/wwamap/wwatxtget.php?cwa=BOX&wwa=winter%20storm%20watch
After looking at the 12Z Euro though 54 hours, my assessment is that it will nudge East from the 6Z run. We shall see..
I donโt know about its 6z, but itโs a bit north of its 00z run
Yes, it got better looking after hour 54. 500mb tugged it back towards the coast. Looking pretty good at hour 66.
NWS has upped the ante on today’s snow
https://www.weather.gov/box/weatherstory
Now 38 here. Just the temperature one wants for snow. ๐
12Z Euro hour 72
https://www.pivotalweather.com/model.php?rh=2026022012&fh=72&dpdt=&mc=&r=conus&p=prateptype_cat_ecmwf-imp&m=ecmwf_full
Sorry for the naive questionโbut how is an AI model different from a โtraditional modelโ. Arenโt both just computer simulations of what might occur?
I am sure TK or WxWatcher could give a better answer, But I found this via a google search
Traditional weather models (Numerical Weather Prediction – NWP) use supercomputers to solve complex physics equations based on current atmospheric conditions, taking hours to run. Conversely,
AI models use historical data and machine learning to identify patterns, generating faster (within minutes), highly accurate forecasts using significantly less computing power
Here’s a non-professional answer.
Most traditional models use physics based equations (with weird names) and try to model the atmosphere. They are referred to as deterministic because they use a single data set to produce a single outcome. The equations are trying to model chaos to give us their single best shot forecast at a point in time.
Most AI models, though deterministic in some sense, are more probabilistic. AI models use tons of historical data to produce a range of probable outcomes. What you often see from them is mean outcome derived from all the probable outcomes. I think some AI models are capable of producing 50 probable outcomes.
AI models are data hungry and many actually got started by using historical data from traditional models. I believe the AI model GenCast imported 40 years of data from the Euro just to get going. They are machine learning animals that gather more data everyday to become better at generating probabilities.
Yes, they are both simulations of what might occur but use different approaches. Both approaches have strengths and weaknesses.
37 degrees here and SNOWING
See how much the temperature drops as the snow continues. ๐
12Z 24 hour EURO 10:1 snow for Sunday/Monday
Big hit South shore
https://www.pivotalweather.com/model.php?m=ecmwf_full&p=sn10_024h-imp&rh=2026022012&fh=84&r=us_ne&dpdt=&mc=
May be one more inch on there as there was snow for a bit more than 24 hours.
Warning level snows back to ORH
Well that is it for the 12Z mode suite.
Score card.
HIT COLUMN
GFS
GFS AI
EURO
EURO AI
ICON
UKMET
GDPS
RDPS
MISS COLUMN
NAM
RRFSA
Onto the 18Z suite……
You forgot to put TK in the miss bucket
I actually did not call for a “miss”.
My current expectations are in the discussion above. ๐
We also have to go into short term guidance mode too.
Thanks TK! So a couple of days ago Sunday’s event seemed like it was going to be a repeat of last big miss going south and east. With that last miss it seemed liked the South Coast was still in play for at least a few inches up until very end but we ended up with just a snow shower. This one now seems different with the Winter Storm Watch being issued already for the South Coast. This will only become more maddening for SSK as the hypers on social media are starting to smell a win here as opposed to the crushing loss they experienced two weeks ago. LOL!
Snow started here around noon. Was quite heavy and trying to accumulate on roads. Itโs trying hard now to be rain/freezing rain. Driveway was slippery getting into house
Pretty dark green echos on radar overhead, yet NOTHING
reaching the ground!!
This is ridiculous. Look at this radar over Boston. NOTHING NOTHING NOTHING is reaching the ground!!!!!
https://radar.weather.gov/station/KBOX/standard
Was 37 here, with snow now 34 and more of a mix now, which is what those brighter returns are down this way.
Thanks TK and Dave for all the model posts. We are in the car in northern VT on the way to Quebec for the weekend, returning Monday night. I knew this storm would come just because we were going to be away!
Talked to my mother earlier as well who is near Albany and she said it was snowing heavily there and accumulating rapidly. Huge silver dollar flakes when it started.
For the record, I’ve been misquoted. I did not call for a “miss” in today’s blog discussion.
Also, winter storm watches and the like are often issued 48 hours ahead of onset. Nothing unusual.
Additionally, a watch is not the same thing as a warning. It will be upgraded accordingly, if needed.
Heavy snow now. No mix. All surfaces covered within 10 minutes
Current heavier precipitation dragging the colder air to the surface (heavier snowfall) – short-lived at any one location.
Exactly the way RRFS depicted it.
FYI: The reason the GFS is trying to simulate 5+ inches of snow at Boston by tonight is a failure of ability to handle boundary layer temps.
Will this impact the rest of the run? Yes.
To what degree? Unknown.
I posted above about hype all week on social media & NOT HERE.
Understood! Thank you. ๐
It’s annoying out there on s.m. but also not surprising. The atmosphere has grown very unpleasant surrounding weather. As you know, I have stated accurately the reasons why this is the case. ๐
Itโs grown unpleasant for every topic. I donโt see it on SM because I block any and all sites itโs on. Darned if I know why anyone wants to read it.
Answering Dave from earlier:
The traditional models and AI models are TOTALLY different under the hood.
Traditional models solve partial differential equations which reflect physical laws, e.g. conservation of momentum, conservation of mass, conservation of energy/heat (thermodynamics), equation of state (relating air properties to density). Crudely speaking, you can think of it as a very complicated form of high school F=ma equation. These equations are solved at each point on the grid (lat,lon,height). But there are also many things that canโt be so nicely represented in equations, and/or involve processes occurring at spatial scales finer than the grid that must be parameterized (i.e. some ad-hoc representation). Some processes are represented empirically (e.g. air-sea heat fluxes). Bottom boundary layer scheme, cloud microphysics, radiation, among other things, are parameterized. All this stuff happens in very dense, long codes (I think most models are still in fortran, at least the ones I work with are). I realize a lot of model bashing occurs on this blog, but given what Iโve outlined above, one can see how โfixingโ them is really a complex process. There is no clear path to take say TKโs assessment of a specific model bias and know what to change above in order to fix it.
AI models know nothing about physics (although there are efforts to make hybrid-AI models that attempt to include some physical aspects, like conservation of mass or energy). They basically take ~50 years of a full 3D state (winds, pressure, temperature, moisture) of the atmosphere, and by examining how the the spatial pattern evolves from one 3D state to one a short time later, it โlearnsโ the behavior. (โartificial intelligenceโ is a curious name, there is nothing intelligent about this process, it is complete brute force). An important note however: how do we have a complete 3D state of the atmosphere every few hours, given actual observations of the atmosphere are very limited in space and time? Well, for that, we use the traditional model to provide this โreanalysisโ, and many problems in the traditional models effectively come back into play (albeit somewhat unclear on how this propagates into the AI solution accuracy).
As I have mentioned here before Iโm very interested in how the operational meteorology fields ends up using the AI models in their proverbial toolbox. I donโt think they should simply be another model โdata pointโ, which is mainly how I see them in use to this point. But figuring out what they are best at, and how to interpret, will take time and experience. In principle I do think they should excel at avoiding some of the model biases that TK is quick to point out; arguably, biases arise from problems/limitations within the traditional models, and that by learning from reanalysis which is nudged back to actual weather the AI model wonโt suffer the same issue. But this is really a complex question.
Wow! Thank you. Nice explanation. Very informative.
So what models do you work with? I’ve been coding for 60 years, so I understand completely how difficult it might be to fix some of the issues, especially so by fixing one issue it might create another and so on and so on.
Absolutely, fixing or improving something (from the standpoint of representation of actual physics) in the model often causes other problems and typically actually (initially) makes performance worse. This is because there is a lot of parameter tuning (i.e. uncertain model parameters are adjusted to give best solution), and the past tuning was effectively compensating somewhat for what you just fixed. This just adds to the difficulty of trying to improve model performance.
I work in the climate modeling domain (either atmosphere-only, ocean-only, or coupled atmos-ocean-land) so alas I’m not working with actual operational weather model codes themselves. (this being said, there is massive code commonality in the weather models and the climate models, they basically are the same, we just run the models out for much longer time periods). If I knew operational weather model code specifics I certainly would share tidbits with the blog! At present we’re doing a lot with CESM, which is NCAR’s climate model that was in the IPCC assessment report. (my background is climate dynamics, but I’ve taught atmospheric dynamics and weather forecasting classes, but my primary function is a researcher). I’ve also done a lot of work with ocean-only models, which are also very similar to atmospheric models (except they include salt instead of moisture)
Thank you so much.
I. Additional to what you have said about fixing issues’ I would imagine there might be turnover in coding staff’ and for a new staffer’ I can imagine the difficulty picking up what someone else had done previously.
Yes; documentation standards in these codes varies, but often it is an effort to follow what the code is doing (if you were not the original author). Sometimes you get lucky with a well-written technical note document, or can find good explanation in published scientific journal papers. As a funny side comment, I’m finding chatgpt is really helpful in sorting through issues with running and or understanding these model codes and configurations! It is not always correct but it brings up relevant things you might have missed.
Thank you.
Can I ask some experts here for some travel related questions on the timing on any stormy potential? Weโre taking a long awaited trip (like, years!) and fly out on Sunday at 9 PM. What does โlate Sundayโ meanโI know itโs beyond my control but are cancellations likely or do things not ramp up until middle of the night, if they do? Weโre coming from Marthaโs Vineyard, so there are just so many factors at play, including wind for the ferry!
Even if a more offshore scenario is indeed what happens, wind will probably be an issue, and a “less snowy” Boston could still be a “very snow” Cape / Islands. If at all possible, my recommendation is to move the departure to earlier if you can.
Thatโs so helpful, thank you! We will probably leave the vineyard on Saturday just to be safeโwe were considering anyway and this helped make that decision.
What window of timing are you thinking for things to potentially start in Boston on Sunday?
Good plan!
Current idea is Boston waits until after sunset to see flakes. That can still shift around.
Ok, thank you! Weโve been waiting for 5 years for this trip and this weather potential is stressful! Thanks for the help.
I wish you the best! Let me know how it goes!
Fat flakes falling here. โ๏ธ
I call them “phat phlakes” ๐
Radar has shown “moderate” precip over me for nearly an hour and the first snowflakes just started at 2:40 p.m.
https://ibb.co/1YXTLNVM
Snowfall forecasts for monday from around the web. Take a look. The hand drawn one is from dave epstein who works for gbh/boston globe.
Thanks Doc!!!
I like him
Sure took FOREVER for the snow to commence here. First flakes around 2PM fro 5 minutes then stopped for anout 20 minutes or so. Been snowing for 20 minutes or so now. No great shakes either except to say pretty big flakes.
Itโs a misty snow here at home
A lot of tiny ice pellets, a few wet snow flakes and a few rain drops for good measure on the Outer Cape. Breezy too. Raw and cold to the bone kind of air.
Now the snow looks a little more interesting. ๐
But it will NOT last long
Really coming down now. At least moderate, borderline HEAVY!
18Z HRRR is stuck at hour 9 and has been for some time.
I HATE it when the models pull this crap!!
Computer issue with 18z run. It’ll get sorted.
Figured something like that.
Thanks
Still snowing hard. Temp dowm to 36 and it is accumulating
Big fluffy snow here in hingham. Temp 34.
Heaviest axis going through here – good for 0.1 so far. Nothing really on pavement though. Just existing snow cover.
Snow has let up some, but still a nice steady light snow. Temp
down to 34. Snow has partially covered pavement and walks
and completely covered roof top, car tops and previous snow cover. Close to 1/2 inch.
ATTENTION PLEASE, FWIW, the 18Z NAM has now officially
boarded the SNOW TRAIN!!!
https://www.pivotalweather.com/model.php?m=nam&p=ref1km_ptype&rh=2026022018&fh=66&r=conus&dpdt=&mc=
Oh so pretty!!
https://www.pivotalweather.com/model.php?m=nam&p=ref1km_ptype&rh=2026022018&fh=69&r=us_ne&dpdt=&mc=
24 hour snow ending 7PM Monday, still a little bit to go, especially S&E of Boston
https://www.pivotalweather.com/model.php?m=nam&p=snku_024h-imp&rh=2026022018&fh=81&r=us_ne&dpdt=&mc=
I remember this model did this at this range when the GFS has been doing the same thing with one of our other threats. It literally moves / redevelops low pressure northwestward for 12 hours. It never actually happened that way.
I want to see the RRFSA come on board. That’s what I am waiting for at this point.
The NAM was OTS on the 12Z run. Did it get an enema between then and now?? Or just GLITCH OUT? I think not.
I think it has finally caught onto what will happen. And that is my opinion and I’m sticking to it.
300 mb at 18Z
https://www.pivotalweather.com/model.php?rh=2026022018&fh=54&dpdt=&mc=&r=conus&p=300wh&m=nam
500 mb at 18Z
https://www.pivotalweather.com/model.php?rh=2026022018&fh=54&dpdt=&mc=&r=conus&p=500wh&m=nam
300 mb at 12Z
https://www.pivotalweather.com/model.php?rh=2026022012&fh=60&dpdt=&mc=&r=conus&p=300wh&m=nam
500 mb at 12Z
https://www.pivotalweather.com/model.php?rh=2026022012&fh=60&dpdt=&mc=&r=conus&p=500wh&m=nam
Makes all the difference in the world.
18Z 3KM NAM also “appears” to be on board.
https://www.pivotalweather.com/model.php?rh=2026022018&fh=60&dpdt=&mc=&r=conus&p=ref1km_ptype&m=nam4km
The 12km version’s precipitation is considerably further north at 06z 2/23 than the 3km version.
But the low centers are virtually at the same lat/lon with only the slightest difference. The 3KM is coming our way.
The 500mb closed low is also virtually in the exact same position.
Channel 7โs map for monday: https://ibb.co/6cKX2Dft
For a first map, quite reasonable in my opinion. I can’t wait to see what happens. Will it come high and tight or low and outside????
Trend is your friend (Sometimes) and the trend is closer to the coast. We shall see if there are any changes with the 0Z suite.
Of course will be checking the 18Z RDPS, ICON and GFS
and of course the 2 EUROS sometime between 715 and 800 PM.
Literally today’s 12Z EURO output
If we do get some snow, will the snow be heavier to move instead of the powder? If the snow is heavier on the trees and wires with possible strong winds not good.
My hopes for a miss might be fading.
Depending on which model one views snow ratio 12-17 to 1
Boston North and down to about 9:1 SE of Boston.
Thanks.
Heavier
Depends on location, but regardless of how much ends up falling, this should be medium to low water content – not as fluffy as some of our events during the cold spell, but more like a 10:1 to 15:1 snow-to-water ratio range.
Earlier in the week someone stated that what happens to today’s event will have an effect on the Sun/Mon event. Is that still true? Haven’t heard that since.
I know the majority of the focus is on snow for Sunday night/Monday but if your along the coast and in South shore or cape and islands, we might want to start seeing what the models are projecting for winds.
Iโve taken a peak and itโs not pretty.
Tom, not sure if you looked at this, but here is the latest NAM wind gusts in MPH
https://ibb.co/Kjpm4PRk
Thanks JpDave !
18z RRFS A
https://www.pivotalweather.com/model.php?m=rrfs_a&p=sfcwind_mslp&rh=2026022018&fh=72&r=us_ne&dpdt=&mc=
There ya go JPDave! On board!
Yup! NOW every stinken model is on board. The kind of consistency I like to see. Sure, there are differences across models and that is to be expected, but now they ALL have it.
Well now the RRFSA is on board, admittedly not to the extent of the others, but it is there now. I was waiting for this and here it is
https://www.pivotalweather.com/model.php?m=rrfs_a&p=ref1km_ptype&rh=2026022012&fh=72&r=conus&dpdt=&mc=
18Z RRFSA total snow, model ratio. Includes aboout 2 inches for today in SNE, so deduct 2 from these.
https://www.pivotalweather.com/model.php?m=rrfs_a&p=snowfall_acc-imp&rh=2026022012&fh=84&r=us_ne&dpdt=&mc=
Note still snowing some in Eastern SNE at the end of the run, so snow could go up an inch or so.
That’s the 12Z. See below for 18Z run.
So that means you lock it in with 100% confidence based on all the model data you wanted to see and nothing can change from here, correct? ๐
j/k of course
Nope, but it is looking more likely than not that this baby is coming up here. Could it still take a right turn, sure.
We watch and we watch……
I still get the feeling a lot of people think I’m calling for a clean miss on this.
NOT the case. ๐
Yikes on the snow totals from RRFSA.
Keep in mind some of this is from today but southeast MA is all the Monday storm.
https://www.pivotalweather.com/model.php?m=rrfs_a&p=snowfall_acc-imp&rh=2026022018&fh=84&r=us_ne&dpdt=&mc=
850 mb jet still more along the south coast. But itโs ferocious.
80-100 kts.
Seeing 960s and 970s pressures.
Again, the snow will get the vast attention, but, this is high end impact possibilities for wind and maybe moderate coastal flood impacts Monday afternoon and those should start, I hope to get local communities attention if this is, in fact, coming closer.
Ever since falling on black ice four years ago Iโm paranoid about slipping and falling again. I had to have surgery to repair my right ankle. Iโm left with sixteen screws and a titanium plate.
I was basically out of commission for about six months with healing and physical therapy. Iโm and for the rest of my life Iโm seventy still dealing with swelling and painful neuropathy the has set in because of the injury. Because of being injured is the reason now I always root for the out to sea outcome. As in life we always donโt get the outcome that we want.
Of course and well understood!!! Understand completely.
18Z ICON comes awfully close.
https://www.pivotalweather.com/model.php?m=icon&p=prateptype_cat_icon-imp&rh=2026022018&fh=72&r=us_ne&dpdt=&mc=
24 hour kuchera snow
https://www.pivotalweather.com/model.php?m=icon&p=snku_024h-imp&rh=2026022018&fh=84&r=us_ne&dpdt=&mc=
Monday at 3:30pm is high tide along eastern Mass
9.1 ft thank goodness, because if this comes even closer with those simulated pressures, Iโm sure it would be capable of a 3+ ft surge, but at least thereโs 3 ft to accept it, as flooding with wave action usually starts when the Boston tide exceeds 12ft
We’re almost to the point now where the guidance will start re-adjusting the backing away from the doomsday scenario.
This has happened a number of times already this winter and I reckon very few people remember them. ๐
Yes.
And for seasons and years beyond that itโs been happening.
Thatโs that very rare case when the models are catching up to how intense something will be, but as you say, the vast majority of time, the models have the worst simulated intensity a couple days out and then adjust downward the last 48 hrs to whatโs actually going to happen.
Thatโs = thereโs
Aside from maybe the GFS, not seeing doomsday, just a strong storm with 6+” for most east of Worcester and some wind. If all these models back down now to very little at 48hrs from onset than what are we really doing with technology? Total reboot required, throw it all out
Not snowing anymore. Iโll guess a sleet/rain mix.
Still snowing lightly here. Temp: 33
I am guessing that a more widespread Winter storm watch will be issued by the NWS This evening sometime or certainly by tomorrow AM, UNLESS there is an Abrupt change to the modeling.
USA men’s hockey up 4-0 against Slovakia in semi-final game.
And Canada won earlier today.
The womenโs US/Canada gold medal game was fantastic and what a move around the Canadian defense, 1 on 1, in overtime, for the winner.
That was an exciting game for sure!
I’ve watched/am watching all three fantastic hockey games. Lots of fun and action.
5-0 now, USA
Red Sox 18, Northeastern Huskies 3 from Ft. Myers.
Duckboat parade Tuesday, weather permitting.
Temp has dropped 5 degrees since it started snowing.
That was made possible by the layer of dry air in the lowest 10,000 feet.
I guess backdown in the models, for me, in this unique upcoming system, is less applicable to precip and way more applicable to storm intensity.
This will be a decent 500 mb feature out over the ocean with all its available moisture.
If it tracks as the 12z suite shows today, a backdown of the models some is not likely to backdown the qpf greatly.
The backdown is whether nantucket gusts to 70 or 55 and whether plymouth/marshfield gusts to 65 or 45/50, etc. thats where a slight intensity backdown would be helpful, in my opinion. ๐
Here’s hoping for no or just minimal snow days, Tom. Do you already have two to make up?
Yes, til June 22nd now.
I thought MAYBE the 18z GFS would give up on trying to give Boston 5 inches of snow by tomorrow morning, but instead it’s gone up to 6.
Basically 6 times as much snowfall than the short range guidance for the same time period.
Yep.
Uncle GFS is running now, out to hour 33.
Yeah, just referenced it above.
As soon as I see the foolishness it’s doing in the first 18 hours, buhbye.
Until I see something definitive, I’m sticking with HHH.
If you want to see an on-the-money Sun-Mon forecast, try Joe Bastardi’s.
I know TK doesn’t want to see this, but here is the 18Z GFS surface map as of 7 AM Monday
https://www.pivotalweather.com/model.php?m=gfs&p=prateptype_cat-imp&rh=2026022018&fh=66&r=us_ne&dpdt=&mc=
24 hour snow ending 1PM MOnday with still a bit more snow to come
https://www.pivotalweather.com/model.php?m=gfs&p=snku_024h-imp&rh=2026022018&fh=75&r=us_ne&dpdt=&mc=
Total snow including the BOGUS 6 inches today for Boston that AIN’T happening. My son just texting saying it is sleeting and raining downtown.
https://www.pivotalweather.com/model.php?m=gfs&p=snku_acc-imp&rh=2026022018&fh=81&r=us_ne&dpdt=&mc=
Yeah I heard somewhere that there would be some sleet & rain involved today.
Yes, not sure where though. How do we get 6 inches of snow if it is sleeting and raining??? I just don’t get that.
Looks like it is now SLEET here.
I guess it’s time for me to turn my blog over to whatever the GFS output is and retire from it. ๐
GFS clearly knows meteorology superior to any human. I mean, after all, it’s NEVER wrong. ๐
never ever been wrong! ๐ ๐ ๐
I see em, I post em. ๐
It’s just us.
Oh that much I know. I was just trying to make the GFS feel better about its pitiful self. ๐
he he he It’s just along for the ride with the rest of the gang.
Now itโs a snow/sleet mix here.
Eric is calling for 10-16โ for Boston and 16โ+ SE MA!
Wow! โ๏ธ
My first call will be on tomorrow morning’s update.
Thanks, TK.
We drove to Framingham and back this afternoon โ not as early as we had hoped. Outbound involved big snowflakes and poor visibility. The return trip was more mixed junk, and what weโre getting now keeps changing its mind, maybe because itโs 32 degrees.
It’s more due to warming aloft.
Here is another Bernie video
https://www.instagram.com/reel/DU_ZI-_kSgw/
Dang, canโt access instagram. I used to love watching his accuweather videos.
https://www.pivotalweather.com/model.php?m=gfs&p=850wh&rh=2026022018&fh=72&r=us_ne&dpdt=&mc=
This is not to illustrate the accuracy of the GFS, more to point out if a storm of simulated intensity comes even closer, it lifts an extremely impressive low level jet square up over the region.
Yup.
This is getting interestinger and interestinger. ๐
Interesting bands of precipitation on radar
https://radar.weather.gov/station/KBOX/standard
Eric posted one hell of a snow map for Sun-Mon!
60-72 hrs out, Iโm of the mindset that we have suggestions of somewhat closer system Monday.
Beyond that, still a lot of uncertainly. Need to see tomorrows 00 and 12z suites before feeling moderate to higher confidence.
We arenโt though 60-72 hours out. About 48 hours or am I missing something.
I see that will go up if this comes. GFS kuchera has widespread 25+
Wow the 18z GFS is a hall of fame look for the esteem seaboard. 20+ inches from Philadelphia to Boston. That would be something.