March 2-4th ... first -NAO anchored storm perhaps in years

[powderfreak]

4 minutes ago, weathafella said:

No.  I’m asking why in heavy precipitation it would rain under 1500 feet a a storm tight snow up?  

I don't know, I've seen plenty of heavy precip events where it's not automatic that it snows to the valley floors.  I guess I'm not sure why an elevation event in this case would be all that outlandish.  Seems like it's an option that is possible.

Especially if talking storm total precip of say .5-1.0" instead of 2-4".

[Hoth]

Just out of curiosity, does anyone know how the modeled 850-700mb temps compare to the October snowstorm? Was that colder aloft?

[powderfreak]

Just now, Hoth said:

Just out of curiosity, does anyone know how the modeled 850-700mb temps compare to the October snowstorm? Was that colder aloft?

I think that was ridiculously cold for October... I remember like -6C at H85 or something for the Pike region?

[Hoth]

Just now, powderfreak said:

I think that was ridiculously cold for October... I remember like -6C at H85 or something for the Pike region?

Ok, so a few degrees cooler than the upcoming system. Thanks!

[powderfreak]

12 minutes ago, weathafella said:

I think if it bombs, there will be no issues in low elevations after a period of heavy rain.

I agree if it goes full firehose but it could also be an elevation event if it ends up to be a more drawn out moderate precip event.  Like a 6-12" hills and 2-6" lower elevations after some rain if you are in the .5-1.0" QPF range.  

If it's a 3" QPF firehose bomb then yeah it's probably wet snow at least outside of valley areas that have some downslope compressional warming aspect.  

In strong flow events weird stuff happens.  It may not be universal snow levels, if there's any upward motion due to terrain or speed convergence then it's snowing at a lower elevations, but if there's any downward motion like the backside of a standing wave pattern or lee side valley it could be raining.  That extra 1C warming or cooling from orographics can make all the difference.

[wxsniss]

1 hour ago, ORH_wxman said:

I'm actually fairly optimistic about this one. I'm also in a decent spot on the east slopes near the pike too...but even for areas like Kevin and maybe Ginxy I'd be cautiously optimistic.

The thing to watch for is the phasing obviously, but also look out for subtle changes in the block and our big system coming ashore in the PAC NW behind this one too.

 

For all our anecdotal experience with anomalously dynamic systems, I'm fairly confident about a closer track than that depicted on the southeast-trending 12z OP runs today.

What I'm less confident about is thermal profiles and ptype... we kind of got a flavor of the potential with yesterday's runs... but for SNE at least, most of any heavy snow potential comes in the 2nd act after secondary cyclogenesis, and there's still much synoptic and mesoscale uncertainty (retrograding low? mid-level fronto? duration of easterly flow?) to call for anything with certainty. ORH-SNH has looked to me the best bet for days.

[HIPPYVALLEY]

5 minutes ago, Hoth said:

Just out of curiosity, does anyone know how the modeled 850-700mb temps compare to the October snowstorm? Was that colder aloft?

Iirc, much better high placement for that one. 

[weathafella]

9 minutes ago, powderfreak said:

I don't know, I've seen plenty of heavy precip events where it's not automatic that it snows to the valley floors.  I guess I'm not sure why an elevation event in this case would be all that outlandish.  Seems like it's an option that is possible.

Especially if talking storm total precip of say .5-1.0" instead of 2-4".

But we’re talking if it bombs.  If it’s pedestrian then sure-but I lose interest at that point.

[mreaves]

32 minutes ago, dryslot said:

Nice analysis, Legro laying it out....

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
***Significant Coastal Storm Possible Late in the Week***

The focus of the extended was mainly on potential for
significant impacts from a coastal storm late in the week...with
a weaker/lighter event Wed night.

For starters Wed...developing return flow aloft will combine
with approaching S/WV trof to produce a band of frontogenesis
along the mid level warm front. While the bulk of the forcing
for ascent looks to remain along the Nrn forecast zones...that
does leave room for some accumulating snowfall across the mtns.
That forcing will be mainly over The County...but 2 to 4 inches
are possible over the Wrn ME mtns before the best lift drifts
Ewd.

That takes us to a more significant pair of S/WVs across the
central CONUS. The Nly wave...arriving in the Pacific Northwest
Tue...and the Sly wave currently dropping down the West Coast
will begin to phase near or E of the MS River. Low pressure will
develop and track NEwd...but developing ridging over Greenland
will provide no escape N. Eventually secondary low pressure is
forecast to develop S of Srn New England and track in an Ely
direction out into the Atlantic. In a general sense this means a
slower moving system with deep Ely flow ahead of it. Model
guidance has had some run to run consistency issues...but
generally within the envelope of ensemble guidance. To me it
looks like the run to run changes are mostly related to the
degree of phasing between S/WV trofs across the central CONUS. A
weak or missed phase results in a weaker primary low and system
that gets strung out and blocked S of the forecast area. A
more complete phase leads to a stronger primary low...more
ridging ahead of the system...and enough forcing for Nwd
movement to counter- balance the developing Greenland block. The
latter scenario would lead to a more impactful and more
widespread precip event for the forecast area.

That being said...26.12z GEFS guidance is forecasting a -3 to -4
sigma H8 u wind anomaly to develop over much of Srn and central
New England by Fri morning. That type of deep Ely inflow is
typically a good signal for precip in the area...as well as Ely
upslope enhancement of precip in the White Mtns and Monadnocks.
Additionally...26.12z ECMWF EPS probabilistic guidance has a 40
to 50 percent chance of 0.50 inches QPF in a 24 hour period
ending 03.00z Sat. So I will keep the likely PoP of some
measurable precip that the multi- model consensus forecasts for
Srn NH up to the Lakes Region and far SWrn ME.
Finally...significant spread exists to the N of the ensemble
mean...with very little spread to the S. If guidance were to
shift...it would suggest to me a Nwd shift is most likely. At
least one of the S/WVs in question has not arrived over land
based sampling stations yet...so it may be another 24 hours
before model guidance gets a good handle on ingredients.

For now I will remain fairly conservative on precip...with less
than 0.50 inches QPF total across the NH/MA border. Temps will
also be on the mild side at onset...but temps aloft remain
fairly cold. With H9 temps -2 to -4C on the 26.12z ECMWF...the
most likely scenario would be a wet snow with surface temps
possibly at or above freezing. The current forecast calls for
light accumulations across Srn NH. If model guidance trends
Nwd...that would obviously increase QPF and resulting snow
amounts. Though I think it is less likely than a dry forecast or
snowier forecast...there is also a small chance that guidance
trends warmer and wetter...which could lead to some snow
melt/runoff related flooding. Greatest impacts are expected Fri
morning at this time...though changes in timing are possible at
this range.

Regardless of the interior impacts from this
system...significant coastal impacts are expected even with a
more Sly track. For information about marine interests and
coastal flooding see sections below.

 

No mention of the chickens in Northfield, NH though.

[ORH_wxman]

Yeah I think if you have a bombing system in the sweet spot (prob 25 mi S to 75 mi N of benchmark), most of SNE will see snow away from the obvious spots like the cape and prob south coast. A moderate to heavy event that isn't a juggernaut will prob be an ORH to Berkshire/monads special. 

Of course there's always a chance too this goes insane and it's a 3 inch rainstorm in SNE with a low over Newport RI while powderfreak is doing naked snow angels...but the chance of that is prob lower right now than the other two options. 

[powderfreak]

5 minutes ago, weathafella said:

But we’re talking if it bombs.  If it’s pedestrian then sure-but I lose interest at that point.

I'd almost lean that even if it bombs it still is somewhat of an elevational event.  I think the north-south valleys have some issues if it's a bombing out strong east flow.  How many times have we seen that in big strong storms?  Plenty.  

[ORH_wxman]

Just now, powderfreak said:

I'd almost lean that even if it bombs it still is somewhat of an elevational event.  I think the north-south valleys have some issues if it's a bombing out strong east flow.  How many times have we seen that in big strong storms?  Plenty.  

It's possible places like CEF get screwed even in the juggernaut scenario but there's a chance we maybe have slightly more NE flow at the sfc in this one versus a Dec 92 type which had the high further east. But that is something we will have to check when we get closer. It is def a deeper layer easterly flow event...but if that bottom couple thousand feet is more like 050-060 vs 070-080 then it could make a difference. 

[weathafella]

3 minutes ago, powderfreak said:

I'd almost lean that even if it bombs it still is somewhat of an elevational event.  I think the north-south valleys have some issues if it's a bombing out strong east flow.  How many times have we seen that in big strong storms?  Plenty.  

See Will’s post above yours.   

[mreaves]

3 minutes ago, ORH_wxman said:

Yeah I think if you have a bombing system in the sweet spot (prob 25 mi S to 75 mi N of benchmark), most of SNE will see snow away from the obvious spots like the cape and prob south coast. A moderate to heavy event that isn't a juggernaut will prob be an ORH to Berkshire/monads special. 

Of course there's always a chance too this goes insane and it's a 3 inch rainstorm in SNE with a low over Newport RI while powderfreak is doing naked snow angels...but the chance of that is prob lower right now than the other two options. 

[ORH_wxman]

Just now, weathafella said:

See Will’s post above yours.   

E MA def wouldn't have the downslope issues that the CT valley could have. 

[AfewUniversesBelowNormal]

Maybe it will stall for a few days or the one after it will, the Atlantic ridge has been over amped pretty continuously for about the past week. I've been posting GOES images. Can't really see it breaking east of that magnet spot along the coast

[40/70 Benchmark]

8 minutes ago, powderfreak said:

I'd almost lean that even if it bombs it still is somewhat of an elevational event.  I think the north-south valleys have some issues if it's a bombing out strong east flow.  How many times have we seen that in big strong storms?  Plenty.  

Its not an elevation event in e MA if it bombs.

[powderfreak]

1 minute ago, ORH_wxman said:

It's possible places like CEF get screwed even in the juggernaut scenario but there's a chance we maybe have slightly more NE flow at the sfc in this one versus a Dec 92 type which had the high further east. But that is something we will have to check when we get closer. It is def a deeper layer easterly flow event...but if that bottom couple thousand feet is more like 050-060 vs 070-080 then it could make a difference. 

True, I just think the more you get into the up and down terrain of the interior it might become more elevational in nature, especially if the low level flow starts messing with precipitation rates and small pockets of low level lift/sinking couplets.

[WinterWolf]

3 minutes ago, HIPPYVALLEY said:

Iirc, much better high placement for that one. 

But...that one (Oct 11) was supposed to be/forecast to be(right up to the very start as well) rain to start, and rain for most all the afternoon in central areas/and areas that didn’t have any elevation.  Which for October, would make total sense.  Well from the very first drop of precip it was snow here!!  And it snowed all day and through midnight...in October. Truly a total forecast bust with that one for most areas. And it was very warm the days before...much warmer than it will be this week.  Not saying this is the same obviously...but that one was not supposed to do what it did either.  Nobody/station had  a foot of snow for central CT for that one...nobody would have believed it any how. 

 

Nobody called for that or expected it...but JB said that one was gonna go nuts for SNE. So he got that one completely right.  And he got Sandy right.  So this being a highly Anomolous set up as well, I think he may be on to something here...we’ll see. 

I think Will’s ideas about a bombing low makes total sense.  Obviously if this doesn’t come together..it’s toast for most in SNE. 

 

[powderfreak]

5 minutes ago, 40/70 Benchmark said:

Its not an elevation event in e MA if it bombs.

Ok fair enough I agree but there is more to New England than E.Ma...thought the original comment was more a general northeastern comment based on Bastardi's comments. 

We'll see what happens but an elevational event in areas with varying terrain wouldn't surprise me.  That's all.

Also, just because its snowing at all elevations doesn't mean it can't be an elevational event.  You get 12" at 33F and ORH gets 24" at 30F...that's still pretty elevation dependent. 

[ineedsnow]

SREFS look pretty cold and juicy .. But still far out...

[ORH_wxman]

Just now, WinterWolf said:

But...that one (Oct 11) was supposed to be/forecast to be(right up to the very start as well) rain to start, and rain for most all the afternoon in central areas/and areas that didn’t have any elevation.  Which for October, would make total sense.  Well from the very first drop of precip it was snow here!!  And it snowed all day and through midnight...in October. Truly a total forecast bust with that one for most areas. And it was very warm the days before...much warmer than it will be this week.  Not saying this is the same obviously...but that one was not supposed to do what it did either.  Nobody/station had  a foot of snow for central CT for that one...nobody would have believed it any how. 

 

Nobody called for that or expected it...but JB said that one was gonna go nuts for SNE. So he got that one completely right.  And he got Sandy right.  So this being a highly Anomolous set up as well, I think he may be on to something here...we’ll see. 

I think Will’s ideas about a bombing low makes total sense.  Obviously if this doesn’t come together..it’s toast for most in SNE. 

 

This one will def have to bomb prettt nicely. October had a very cold lower mid-level to it. It was like -6 to -7 at 850 and even 925 was like -3 to -4. Really cold stuff. It was never going to rain long in that if it started as rain (and obviously for some it never did)...some TV mets not named Ryan got fooled pretty bad on that. 

But this one is gonna have to work a bit...and we obviously know that they can. You just need that really rapid deepening of the mid and upper levels which will really force the cooling aloft. It's not super warm to start...we got close to 540 thickness, it's just kind of mild in the lower 4000-5000 feet. 

[40/70 Benchmark]

4 minutes ago, powderfreak said:

Ok but there is a lot else to New England than E.Ma...thought the original comment was more a general northeastern comment based on Bastardi's comments. 

We'll see what happens but an elevational event in areas with varying terrain wouldn't surprise me.  That's all.

I understand there is more to New England than e MA, but I took the liberty of qualifying your statement since you neglected to do so.

You're welcome.

[TalcottWx]

I'll say this: pretty damn close to sure thing it bombs. Haven't seen much suggest otherwise.

[powderfreak]

3 minutes ago, 40/70 Benchmark said:

I understand there is more to New England than e MA, but I took the liberty of qualifying your statement since you neglected to do so.

You're welcome.

Much appreciated lol.

[HIPPYVALLEY]

5 minutes ago, ineedsnow said:

SREFS look pretty cold and juicy .. But still far out...

soooo far out in terms of their usefulness but another piece to look at I suppose. 

[CoastalWx]

Tension

[CT Rain]

10 minutes ago, WinterWolf said:

But...that one (Oct 11) was supposed to be/forecast to be(right up to the very start as well) rain to start, and rain for most all the afternoon in central areas/and areas that didn’t have any elevation.  Which for October, would make total sense.  Well from the very first drop of precip it was snow here!!  And it snowed all day and through midnight...in October. Truly a total forecast bust with that one for most areas. And it was very warm the days before...much warmer than it will be this week.  Not saying this is the same obviously...but that one was not supposed to do what it did either.  Nobody/station had  a foot of snow for central CT for that one...nobody would have believed it any how. 

 

Nobody called for that or expected it...but JB said that one was gonna go nuts for SNE. So he got that one completely right.  And he got Sandy right.  So this being a highly Anomolous set up as well, I think he may be on to something here...we’ll see. 

I think Will’s ideas about a bombing low makes total sense.  Obviously if this doesn’t come together..it’s toast for most in SNE. 

 

We had 6-12" for all of interior CT (including the valley) the day prior. 

We missed the 12-24" in the hills!

[dryslot]

1 minute ago, CoastalWx said:

Tension

Sides being taken, Lines being drawn.

[weathafella]

Just now, dryslot said:

Sides being taken, Lines being drawn.

There’s something happening here....what it is ain’t exactly clear....