Big Snow threat, what will it do, part II

[Typhoon Tip]

can anyone please explain to me why there is that donut hole on the h7 RH maps (translating down to the surface)???

 

Looking at the h5, I would think there would be a low getting ready to deepen close to the coast

 

That is not uncommon during Miller-Bs.   The way it works is, the primary and its supportive dynamics has an enhanced RH field associated with it, but as it nears the Mt.s and/or dammed air, the surface circulation gets "stuck" so to speak, and that cuts into saturation because of limiting some of the UVM.  The supportive dynamics then abandons the primary, and the 2ndary is actually a new low (in essence it really is a misnomer to think of it as a transfer -- nothing is really being transfered).  Anyway the new low and mechanic go to work and saturate the column farther E.  So what you end up in total is saturation with the primary, a "humidity jump" it is sometimes referred, then a new region of saturation with the 2ndary.    

[dendrite]

21z RPM thru 64 hours... Subsidence much? 

Pic is damn small, but we need to save that for Ray.

[ace0927]

And at the same time you have 2/83 and 2/8/13 which to me were lousier overall setups than this one in many ways yet blew away what this will probably do.

2/83 had one of the better east based blocks ive seen on maps

[wxeyeNH]

Barry seems to have a better understanding of OE enhancement. The other two seem clueless

Your absolutely right.  With such a cold airmass and a NE wind the southshore should have a max area with ocean enhancement.  Barry shows that well on his maps.  Other guys ignore this important fact.  Im going to miss Barry and Harvey when they retire, the last of the great mets!

[ace0927]

You can follow the evolution of it in the RH panels here.

 

http://www.meteo.psu.edu/~fxg1/ETANE9_18z/etaloop.html

thanks, Dentrite

[ace0927]

21z RPM thru 64 hours... Subsidence much? 

tiny pics?

[wx2fish]

21z RPM thru 64 hours... Subsidence much?

Heavy caution with that model at this range. What a weenie run lol

[BostonWX]

Pic is damn small, but we need to save that for Ray.

 

It evens off a bit at the end of the run haha. Light snows still going across E coastal mass and the Cape

[SnowGoose69]

That is not uncommon during Miller-Bs.   The way it works is, the primary and its supportive dynamics has an enhanced RH field associated with it, but as it nears the Mt.s and/or dammed air, the surface circulation gets "stuck" so to speak, and that cuts into saturation because of limiting some of the UVM.  The supportive dynamics then abandons the primary, and the 2ndary is actually a new low (in essence it really is a misnomer to think of it as a transfer -- nothing is really being transfered).  Anyway the new low and mechanic go to work and saturate the column farther E.  So what you end up in total is saturation with the primary, a "humidity jump" it is sometimes referred, then a new region of saturation with the 2ndary.    

 

Its pretty darn unusual however to see it where it is in this case, the vast majority of your Miller B screw zones occur over the DC region, maybe S PA and sometimes we'll see it in CPA or EPA but its fairly unusual at least off memory to see a Miller B that screws NYC totally which is what the NAM had been trying to do before its 18z run, the only instances I recall where that region has been shafted in Miller Bs is usually when they are too warm and the inland low is too late to transfer, but this case is not really why the NAM was showing that.

[ace0927]

It evens off a bit at the end of the run haha. Light snows still going across E coastal mass and the Cape

Damn - 12-16" even down this way - where do I sign?

[weatherMA]

Many sicknesses cancelled my NY plans, so looks like heavy heavy 00z models to ring in the new year.

[bboughton]

It evens off a bit at the end of the run haha. Light snows still going across E coastal mass and the Cape

 

I'll take it.

[ace0927]

It evens off a bit at the end of the run haha. Light snows still going across E coastal mass and the Cape

That snowfall distribution has similarities to Dec 1995, no? I always thought that was a good analog here

 

edit: on second glance of h5 maps...that one has a closed off center at h5

[40/70 Benchmark]

21z RPM thru 64 hours... Subsidence much? 

My absolute worst fear.

 

Dec 2003 redux.

 

Always a risk for me in these type of systems....I'm always leery of an immediate coast jackpot.

[Chrisrotary12]

This is the map that I am running with for now.  

 

[SnowGoose69]

That snowfall distribution has similarities to Dec 1995, no? I always thought that was a good analog here

 

edit: on second glance of h5 maps...that one has a closed off center at h5

 

Its popping onto some of the CIPS analogs, it had the funky situation with the vort at 500 lagging way behind the surface low which gave some areas 4-5 inches of snow on the backend.

[40/70 Benchmark]

Its pretty darn unusual however to see it where it is in this case, the vast majority of your Miller B screw zones occur over the DC region, maybe S PA and sometimes we'll see it in CPA or EPA but its fairly unusual at least off memory to see a Miller B that screws NYC totally which is what the NAM had been trying to do before its 18z run, the only instances I recall where that region has been shafted in Miller Bs is usually when they are too warm and the inland low is too late to transfer, but this case is not really why the NAM was showing that.

That, and if they are just too late t develop (Miller B-East), which is admittedly relatively rare.

[40/70 Benchmark]

Obviously those amounts are high, but subtract 5" and that is a possibility.

Qualitatively sound.

[Clinch Leatherwood]

tiny pics?

 

little pics for a model with little credibility most of the time at this range.

[moneypitmike]

 

2 different things going on. You have the initial overrunning from I90 through New England...then the developing secondary off the SE coast.

 

 

If the overrunning works out I wonder if we see two jackpot areas - one in N MA/SNH and one South Shore down to the Cape.

 

I'm counting on the overrunning out here.  Unless this ends up being much more amped and tied tight, GC is fringed on the coastal.

 

I share the concern Mitch expressed (I think Mitch said it) about the overrunning--hoping that the moisture for that doesn't get robbed the developing low leaving this area in the midst of a 7-10 split.  But, in my new world, I'm just going to enjoy whatever I might eek out.

 

Temp is climbing a fair bit out here in GC.  Up 4.5* since 5:00p.m. to 19.5*. Just had a strong burst of north wind about 15 minutes ago---reenforcing shot of cool air incoming methinks.

[40/70 Benchmark]

Not 20"+...16-20" in the max zone.

 

I actually like that map, qualitatively speaking....just knock th max zone down 5".

 

Gives me 10"....about right.

[SnowMan]

This is the map that I am running with for now.

Conservative approach

[CoastalWx]

Ease off the RPM guys.

[moneypitmike]

Here's channel 40's take.  I guess at this time frame it's okay.  My guess at this point is that it'll be refined and have the maxes trimmed back out west and maintained (or maybe even increased) in the eastern areas.

 

 

[Tropopause_Fold]

happy new year ladies and gents.

 

may 2014 be full of snow, fakenadoes and 'canes.

[Clinch Leatherwood]

Many sicknesses cancelled my NY plans, so looks like heavy heavy 00z models to ring in the new year.

 

Yeah it's an ugly week or two for bugs.  Half our party came down with the stomach bug which cut the trip short a few days. 

[SnowMan]

happy new year ladies and gents.

may 2014 be full of snow, fakenadoes and 'canes.

Yes Happy New Year to all! May 0z bring us all heavy heavy snows.

[Clinch Leatherwood]

Ease off the RPM guys.

 

If the NAM and NCEP can take a lot of abuse so can the RPM.  It's had a few good moments over the years but for the most part...not.   I doubt at this range it's going to outscore the majority of the other guidance...but we will see.

[Typhoon Tip]

Its pretty darn unusual however to see it where it is in this case, the vast majority of your Miller B screw zones occur over the DC region, maybe S PA and sometimes we'll see it in CPA or EPA but its fairly unusual at least off memory to see a Miller B that screws NYC totally which is what the NAM had been trying to do before its 18z run, the only instances I recall where that region has been shafted in Miller Bs is usually when they are too warm and the inland low is too late to transfer, but this case is not really why the NAM was showing that.

 

Yeah, I think the climo on that is a bit farther S than NYC.  I actually didn't look to closely as to exactly where it is doing that, but when the poster asked it seemed like a smoking gun for that whole humidity leap scenario.  

[jm1220]

seriously forky. it's so close to being something much more potent/significant.

I remember models overemphasizing the lead vort/wave too much before, especially 12/19/09 and then coming around in the end. I think we'll see a better reflection near the coast if the good 500mb pattern keeps up.