March 22-23 Storm Thread: Cabins and Pony-Os?

[powderfreak]

Still decent spread on the ensembles for low track but huge circulation and marginal air mass, even in the NNE valleys make for a difficult forecast.  Adirondacks and Green Mtns above 1,000-1,500ft seem in the best location for significant snow at this time.  Hopefully we can get at least some snow into the SNE hills to make this more interesting for the forum.  

[purduewx80]

Can already see a surface reflection offshore the Carolinas this morning. Most guidance brings this inland overnight, but it will be important to watch whether or not convection can keep it tied to the Gulf Stream tonight. If that occurs (big IF), then areas outside of the higher terrain may have a chance to flip to snow since the surface low would track farther offshore than the overnight consensus indicates.

[Typhoon Tip]

15 minutes ago, purduewx80 said:

Can already see a surface reflection offshore the Carolinas this morning. Most guidance brings this inland overnight, but it will be important to watch whether or not convection can keep it tied to the Gulf Stream tonight. If that occurs (big IF), then areas outside of the higher terrain may have a chance to flip to snow since the surface low would track farther offshore than the overnight consensus indicates.

I'm dubious of the warm complexion in the runs ... even with the higher resolution dependable guidance.. 

There are some operational checklist items for uncertainty ... sort of non-disclosed or unwritten that we all know about.  I'd say this system has a higher probability for "unintended consequences" ... than normal uncertainty goes. 

For one, cut off lows... they tend to be fickle beasts and when they boundary off from the ambient synoptics and close of circuitry of thermodynamics, they get sort of "invisible" to the guidance at that point...  This is true even for quasi-closed structures that are still moving along with the flow but have a node mid level height core that's substantially below the surrounding medium.  I'd say taking 544 heights to 530 surface somewhere over Logan and keeping this all rain is suspect -  Jesus at those heights it would snow ball at 40 F..  I mean, forget the closed low uncertainty thing; heights below 534 dms and all rain on the NW arc of a bombed low is rare.

Secondly, once the coastal gets really structured ...circa ISP to Cape Cod or just SE of there... any elevated warm layers abolish to the CCB genesis and the sounding will become isolinear below 800 mb or so... At which time the QPF is coming from a trowal and/or jet mechanics and so forth ... above said cooled layer.  Even if it's 35 or 36 F you can blue tint the air with pine sag and power line cake. 

We'll see...  I don't really have care about being right or wrong ... I just like covering the philosophies of these deals

 

[dryslot]

37 minutes ago, powderfreak said:

Still decent spread on the ensembles for low track but huge circulation and marginal air mass, even in the NNE valleys make for a difficult forecast.  Adirondacks and Green Mtns above 1,000-1,500ft seem in the best location for significant snow at this time.  Hopefully we can get at least some snow into the SNE hills to make this more interesting for the forum.  

Where has the trend been over the last few runs as far as the mean track? Are we moving west or east?

[purduewx80]

2 minutes ago, Typhoon Tip said:

There are some operational checklist items for uncertainty ... sort of non-disclosed or unwritten that we all know about.  I'd say this system has a higher probability for "unintended consequences" ... than normal uncertainty goes. 

Totally agree. 

Whatever low the Canadian members are trying to blow up farther S/E will probably be more of a triple point that will erupt later - once the 3rd piece of energy dives in and closes off. 

[ORH_wxman]

The whole thing gets captured by the lakes energy about 12 hours and 100-150 miles too late. I think it would be a lot more interesting if it was sooner and further south.

 

Most of the interesting snow will probably be Greens (down to Mitch too) and then later on Alex up in the whites with big synoptic-aided upslope and maybe Mahoosucs in Maine and up toward Sugarloaf/Jackman. There's a chance at some bursts of moderate to heavy snow in SNE with the ULL, but they will probably be more showery in nature and accumulations will be tough...maybe high terrain can squeak out an inch or two. West slopes of the Berks will prob do well with the synoptic-enhanced upslope too after the storm passes.

[OceanStWx]

36 minutes ago, purduewx80 said:

Can already see a surface reflection offshore the Carolinas this morning. Most guidance brings this inland overnight, but it will be important to watch whether or not convection can keep it tied to the Gulf Stream tonight. If that occurs (big IF), then areas outside of the higher terrain may have a chance to flip to snow since the surface low would track farther offshore than the overnight consensus indicates.

That feature is definitely going to have implications on the forecast. The 3 upper PV anomalies are fairly well resolved by the models at this point, but low level PV anomalies are a little trickier. But the constructive interference of lower and upper level PV anomalies coupling in the vertical can be huge drivers of rapid cyclogenesis.

[jbenedet]

44 minutes ago, purduewx80 said:

Can already see a surface reflection offshore the Carolinas this morning. Most guidance brings this inland overnight, but it will be important to watch whether or not convection can keep it tied to the Gulf Stream tonight. If that occurs (big IF), then areas outside of the higher terrain may have a chance to flip to snow since the surface low would track farther offshore than the overnight consensus indicates.

The Nam is the only pc of guidance with 3 competing SLP’s - the one above, one out towards Bermuda and another that develops later about halfway in between both. It seems to me based on guidance consensus, the NAM’s trend, and where the 12z NAM ultimately tracks the main surface reflection (into the GOM) that it’s the latter SLP that predominates. I’m thinking the NAM is having difficulty resolving which is the area of best surface pressure falls and is reflecting this with 3 distinct SLP’s in the same region rather than consolidating it early on. 

[powderfreak]

NAM is coming around... but further east and no longer only a NNY event as it looks a lot more like these go from a climo standpoint.  

This snow map is WAY over done in the lower elevations IMO, but has the cyclonic NW flow pattern to the output.  This is the climo look for that sort of thing. 

I think this is a real elevation type event the more I look at it.  1-4" lower els but 8-14" above 1000-1500ft. 

[Typhoon Tip]

48 minutes ago, purduewx80 said:

Totally agree. 

Whatever low the Canadian members are trying to blow up farther S/E will probably be more of a triple point that will erupt later - once the 3rd piece of energy dives in and closes off. 

This thing could have chapters... Total story of the storm told over distinct behaviors.   

Could imagine the first 3rd or so being a kind of non-committal piss of cold rain and shades drawn, then parachutes then wind and way colder than anyone thinks like out of nowhere in the last 4/5ths of the thing. 

In1992, December 9-11 ... We had a punishingly powerful Nor'easter that year. It brought wind and tide damage from Maine/Mass down to NJ ... and best of all for giddy early winter enthusiasts .. one hell of a lot of not predicted snow for interior sections. 

It was different scenario ...not an analog.  However, there was a similar pall of uncertainty. It, too, was a powerful cutting 500 mb surface with a ton of unexhausted mechanics still whirlin' around inside of it. As those used up the heights cored out and first elevations flipped, then the lower els six hours later.  Those that flipped early wound up with an astounding 33" yard-sticker around Worcester hills.  

I was up at UML at the time ... 16" fell there, but that was after 9 hours of nearly 3" cold rain blowing sideways. The late afternoon sky features a curious observation; undulating ceiling masses roiling overhead... and as these seem more obvious at moments, ...the raid drops became larger and "floatier" ... ( indulge me ).  In retrospect, probably the snow line at all of 900 feet ... terminating into 80/20 or 90/10 face smacks and nape zappers.  Ugh. Man, that was a truly intrepid walk across University Ave bridge back to the dorms...  40 mph gusts easy, and the rails and walk along the road being iron grid work with 70 foot under draft did little to make one feel cozy.  Around 8 pm that night we flashed over to snow all at once; to this day and before, I had never seen anything like that.  We literally flashed from cat paw moderate to heavy rain buffeting the sides of Fox Tower, to street lamp snow curtains and visibility under a quarter mile in less than 2 minutes!  No hyperbole.  It even was led either by coincidence ...or not, but a flash of unilateral sky brightening and one of those roller beam buzzer thunder rumbles that seems like it's still going on... 

Anyway... three days before any of that took place, I was sitting in Hist. Of Eng. Lit 101. I was not even a Met major at that time, but would be by the following year... A class mate was. She sat near by and I knew of her and her major because I was already privy to the Lab/Major culture being that was a dork.. .Heh.  She was shaking her head while gazing aimlessly toward the window when asserted that it would be all rain.  "I don't know.  We were just going over the charts ... we have our doubts."  

[40/70 Benchmark]

I remember the forecast was for 4-8", and I ended up with like 18" in that event.

I recall that it flipped in the wee hours of the morning...like 1amish...

[Typhoon Tip]

Well in any case... It's a spring system. Welcome to the wonderful world of deterministic weather when everything is possible.

It's interesting to see the NAM ..and in some respects, the GFS' be so pallid with their surface lows.  Those solutions look more like one of those amorphous ...nebular designed pressure patterns you get later in April ...where the mid levels may look spectacular, but because the lower level thickness gradients are so annihilated/non existent, it stays up there...  basically.  They do get their structures better defined N of here ... probably owing to some of what Will was mentioning regarding the N/stream infusion ... establish those gradients and there you go. They could be right...sure.

Yet the Euro and GGEM being so deep in that 975 range over Boston Light ... with snow probably flashing over in the interior whether for accumulation or not, ... those are disparate scenarios. 

[klw]

GFS at 42 hrs is 4 mb stronger and a tad east of 6Z

https://www.tropicaltidbits.com/analysis/models/?model=gfs&region=neus&pkg=mslp_pcpn_frzn&runtime=2019032012&fh=42

 

And at 48 it is a tad SW

 

so yeah noise

[Ginx snewx]

Rgem with 1.6 qpf snow BVT

[dendrite]

RGEM must be factoring in the full moon physics. 

[powderfreak]

GFS is much more ugly than the meso-models on Friday... NAM seems to have heavier precip and dynamically cools that 850 layer.  GFS is less lift and warmer.

[dendrite]

NCEP should combine the FV3 and op thermals. It’d probably be right on the money. 

[powderfreak]

2 minutes ago, Ginx snewx said:

Rgem with 1.6 qpf snow BVT

It's more like the 3km NAM... that had warning snows falling on Friday before any upslope.  I think the 3km and mesos have the right idea with the cooling but it has to be under that heavier lift.  Wherever that synoptic lift occurs should be able to flip to snow.  GFS pushes it into the Adirondacks, the NAM/WRF are more compact and keep it east into NVT.

This is the first part of the system...I think will be elevation dependent so I'll sell those amounts in BTV area...but the idea is there.

 

[OceanStWx]

Man the 00z ensemble sensitivity still showed a coherent pattern showing up only around 24-36 hours lead time (tied to the first phase of the Ohio Valley shortwaves). 

Still time for adjustments.

[dryslot]

Strength and where the phase happens will say alot to what happens, The kicker is, We could use a kicker for this one and a better air mass

[powderfreak]

25 minutes ago, OceanStWx said:

Man the 00z ensemble sensitivity still showed a coherent pattern showing up only around 24-36 hours lead time (tied to the first phase of the Ohio Valley shortwaves). 

Still time for adjustments.

Yeah these spring lows seem to meander wherever they want in a way.  Very low confidence on what happens during the day Friday but the upslope side of things seems like a lot more stable.  I mean the mechanism for lift doesn't change.  The mountains just sit there.  As long as we can get moisture into southern Quebec, the  backside cyclonic flow will wring it out.  

Might as well issue the warning for Pittsburg, NH now.  

[powderfreak]

The ICON shows what ORH has been talking about.... as the TROWAL swings around and under the low it looks to bring a period of steadier snows SE of the mountains into SNE.  The model has a decent period of snow and 2-4" in spots.

[Lava Rock]

59 minutes ago, powderfreak said:

It's more like the 3km NAM... that had warning snows falling on Friday before any upslope.  I think the 3km and mesos have the right idea with the cooling but it has to be under that heavier lift.  Wherever that synoptic lift occurs should be able to flip to snow.  GFS pushes it into the Adirondacks, the NAM/WRF are more compact and keep it east into NVT.

This is the first part of the system...I think will be elevation dependent so I'll sell those amounts in BTV area...but the idea is there.

 

congrats quebec city?

[BombsAway1288]

4 minutes ago, powderfreak said:

The ICON shows what ORH has been talking about.... as the TROWAL swings around and under the low it looks to bring a period of steadier snows SE of the mountains into SNE.  The model has a decent period of snow and 2-4" in spots.

Too bad it's the ICON

[BombsAway1288]

Just now, Lava Rock said:

congrats quebec city?

Shocking this year, I know. Talk about a major populations center that's just been getting pounded storm after storm. They've had some kind of year

[Damage In Tolland]

17 minutes ago, powderfreak said:

The ICON shows what ORH has been talking about.... as the TROWAL swings around and under the low it looks to bring a period of steadier snows SE of the mountains into SNE.  The model has a decent period of snow and 2-4" in spots.

3-6” here .Nice

[klw]

There was a storm in mid-April of 92 which gave BTV about a foot with less east of the Greens.  I was up and visiting the WRJ area and there was a surprise couple of inches.  Elevation dependent except for West of the Greens.  I have no idea what the set up for the storm was.  It was a couple or a few weeks after the Montpelier floods.

[STILL N OF PIKE]

Let this litte low off Carolinas meander offshore and deepen NNE please

pretty decent shot I’m driving somewhere Friday thats 1500’ and up

want that CCB to Crank and a track near Long Island then Boston(east) . I would love to just go to Kersearge 2500’+

[Kitzbuhel Craver]

Looking pretty likely, isn’t this just gonna rot in the GOM and push that NW flow over the spine? I’m heading up for sure...

[ORH_wxman]

6 minutes ago, Kitzbuhel Craver said:

Looking pretty likely, isn’t this just gonna rot in the GOM and push that NW flow over the spine? I’m heading up for sure...

Yeah Mitch's 'hood right up through Killington and Stowe and Jay peak are a mortal lock for 12"+....with the typical northern favored spots prob 20"+....only way they don't get that is if there is a large scale shift in the whole synoptic setup which seems unlikely.