wxsniss

2 hours ago, Typhoon Tip said:

My bigger take away from these overnight various products ... in whole, we lack antecedent cold. 

Long version of what/why that tenderizes butts ...  Determining this thing's ultimate position in space would be better performed if the baroclinic gradient was not so week. 

You need that dense, cold medium abutted to a waif warm humid air mass. Example, the 'roids version of that is Dec 2005. The thermal packing between NJ and Cape Cod was extraordinary.   In this case?  not extraordinary. In fact, less than even ordinary.  It's the same thickness and synoptic parameters over BTV as it is over ACK upon the arrival of the mid level forcing(s).  The low in the model vision has no axis along which is compelled to position.

These aspect feed back on one another.  With a better defined baroclinic axis, that focuses a vortex centric UVM (upward vertical motion) in the lower altitude of the vortex medium, which causes height falls over that region, and then the phasing aloft that is concurrently happening snaps into place/collocates and whole thing goes synergistic ...and annuls are written.

But here, we have enough mid levels for history but that lacking of those crucial aspects beneath... the low is just physically not limited in hooking W ( Euro).  It's probably something like the 1888, not as a total analog ( no ), but that it may be over top warm intrusion. 

There is time to correct the antecedence colder...  Sometimes in these mid range spring systems, they will look this way in the mid ...ext ranges, with warm air wrapping around the top and the cold underneath, but then as the whole show gets closer in time ... sensitivity seems better and the model physics "detect" more BL (boundary layer) resistance ...  

It's tough, because these guidance' don't put out solutions that are impossible - that's not how this works.   No model is a model if they do that - they are the peregrinations of George01's imagination behind a torpid gaze out the window if they do... 

 

Good post. How was baroclinicity prior to 4/97? I remember temps in mid 60s in days prior.

(And no I’m not making any comparisons... this is purely academic… 4/97 is hallowed territory that may not be repeated in a lifetime…)

Heaviest of event so far under these 35 dbz echoes

Having trouble accumulating on pavement

34/28

Heaviest snow matching with 700mb fronto and looks to enter into pike region in that 7z-8z timeframe I mentioned earlier depicted on the NAM

Moderate snow here in Brookline, coating on grass and cars, 34 / 29

2 hours ago, ORH_wxman said:

I’ve been examining soundings a bit more and if there’s a bust potential at least here near the pike and into metrowest Boston region, it’s that snow would hang on longer….the warm layer is extremely elevated. It’s actually up around H7 and not even the usual “very high up” 725-750 level. NAM even has the warmest layer closer to 675mb….and it’s super thin. It stays like that for a few hours in the 08z to 11z timeframe. 

Cool, great detail... I'll show an example here for everyone...

7z-8z (2am-3am) looks to be some of the best lift in pike region... this off 18z NAM:

For times 9z-12z when multiple vendors show sleet is past pike, >0C temps in the column at KBOS off 18z NAM:

08z 666.70 -1.96

10z 723.60 -0.06 

11z 693.80 -0.26

12z 773.50 -1.26 / 748.20 0.84 / 721.00 1.24 / 692.20 -0.46

In other words, we could have 3-4 more hours of snow than depicted. At least will be curious to nowcast.

Deamplifying shortwaves + lack of antecedent cold air... not our first rodeo this winter... the higher snowfall vendor maps are laughable.

Still think we see a healthy thump ~midnight-5am that amounts to 2-4 inches in Boston metro area. 

This sounding is off the 3k NAM at 4am in metrowest... it's a narrow DGZ and we have to overcome some dry air in the hours before, but still should see good rates for several hours.

Not much room for surprises. Best of a fleeting CCB will be northeast MA into coastal ME... ie., doubt it adds much for mby.

If anything, really poor BL temps (yes we wetbulb but how much) may shave accumulations within ~10 miles of coast even more.

I think Box map may bust in some areas... I'm skeptical areas inside 495 in northeast MA get to 8-12".

4 minutes ago, 40/70 Benchmark said:

Because its horseshit.....cold conveyor belt of horse shit with perhaps some mixing with bullshit.

As always, the key will be timing of changeover from horse to bull. 

8 minutes ago, 40/70 Benchmark said:

I'm already bored of this system...think my ceiling is about 8-9".

Yeah this decrescendoed and became increasingly tiresome.

And haven't seen much support for the Kraft CCB.

I think dreams of our first WSW will be deferred.

You had mentioned this earlier and I like it: Snowfall Depth Positive Change, below is the 0z GFS, I think is very realistic, except I might shave an inch in southern CT:

Just now, STILL N OF PIKE said:

Euro was a carbon copy of 12z w track but another QPF cut as ray was warning  

Echoes of prior Monday's system... decaying dynamics, though this one has a much more robust starting point

Also drier, cut QPF by ~30% compared to 18z run

One important takeaway: did not do the GFS-style CCB

Yeah any changes within noise

A definite tick south

We're actually taking steps towards consensus, models will meet somewhere in the middle. I'd feel good in northern MA on north

Areas further south struggle with that 700-750 tongue

I think Ray's map looks great

Just catching up on day...

Have to increasingly weigh NAM 

For it's remarkable consistency, this would be one of GFS's worst performances if it's wrong.

PBP on 0z: ULL definitely a tick southeast

Yikes didn't mean to set off a semantic debate lol...

I did say it "ticked warmer". "Hold firm" meaning there was no wholesale jump north to match the Euro. Some of this is no doubt noise too.

But I get the nail-biting on the margins. I've been there and not discounting that I'll be there tomorrow.

It is a tick warmer 12z Saturday but then bonafide Miller B

Huge hit northern CT on north... I'd call this GFS holding firm

H7:

Kind of a big GFS run here...

Through hr 45... ULL placement over Indiana looks to me like 18z GFS... ie not NAM way west in Indiana

57 minutes ago, wxsniss said:

And that propagates further downstream... by hour 45, 0z NAM is still in Indiana while 18z GFS was shooting east in Iowa

That's some shoddy geography... I meant NAM still in Illinois while GFS was shooting east in Indiana. Lack of sleep ftl

Yeah ICON did not give up any territory...

NAM and RGEM out of range, we wait for the big guns

Odd run, not much value

It was clear early on that the ULL was potent and charging north

8 minutes ago, wxsniss said:

Fwiw hour 36 (and may not be worth anything), using the test of the ULL placement in Arkansas vs. Missouri at 12z Friday... 0z NAM looks just as north and amped as 18z run... 

And that propagates further downstream... by hour 45, 0z NAM is still in Indiana while 18z GFS was shooting east in Iowa

Fwiw hour 36 (and may not be worth anything), using the test of the ULL placement in Arkansas vs. Missouri at 12z Friday... 0z NAM looks just as north and amped as 18z run... 

Here's what I was talking about above... differences already at 42h (12z Friday)... GFS left, NAM right:

17 minutes ago, 40/70 Benchmark said:

That is clearly a Miller B take over, as opposed to confluence forced attennuation.

Guidance tried to do that at the last moment with the Tuesday deal and it was total BS.

Agree

Tip summed it: we've been headfaked by compelling guidance so many times this winter, and by a similar synopsis just days ago. On the other hand, GFS has been amazingly steady relative to the Euro.

I haven't looked carefully but someone should check upstream realtime location of the ULL ejecting from the southwest. For example at hour 12z Friday, GFS has it over central-south Arkansas vs. NAM has it already into Missouri vs. Euro has it northern Arkansas. The differences amplify from there.

Just catching up, noticed 12z/18z GFS close H7, nice CCB

Tough forecast for the margins, especially ~ pike south... 50 mile error is well within range

ICON looks like carbon copy of GFS

24hr snowfall on 6z GFS, 10:1

key thing to highlight... this is all under 84hrs I think for the first time this season...!