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December 27/28 Storm Part II


Typhoon Tip

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Hi all,

I thought I would start a new thread as we are getting this system into the 3rd and 4th period - where we may start to gain some clearer picture of what will transpire. ...Or at least discuss what that may be with a bit more than mere guess-work.

Right now the top analogs for this event appear to offer a period of ice after front end snow thump for the interior between Rt 2 and the Pike, with a change to rain S of there; but I have to say, I suggest not dropping guard for ice in farther S zones.

Also, with polar high initially in a good location, and the 500mb vort max passing safely south of the area, there is certainly room for now-cast correction - and in fact I almost expect that to happen. But we'll see.

From the Mohawk Trail region of Mass and points N, welcome to snowdom! Obviously more in the els, but I like the idea of 6-8" along the corridor its self (low end warning for snow) with some contamination at the mid points keeping them from the 12-15+ amts farther N. Then we need to keep in mind that some of the lesser reliable guidance have dynamical cooling and collapse in the last 15% or so of the event - that may actually sweep some flashing and snow in the air into southern zones late.

Nice multi-faceted event with high wind potential SE, ranging to a upper midland, lower major snow scenario NW, with icing and transition headaches to iron out in between.

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18Z NAM coming in warmer than the 12Z run. It doesn't seem to want to cave into the colder globals and has a sleet fest getting into CNE and is rain for all of SNE outside of the northern Berks by 09Z Thursday. Either it's on to something or it's going to bust very badly. Unless, the 18Z GFS and the rest of the 00Z suite suddenly give in, the NAM is going to bust very badly. I will continue to ride the colder consensus for now.

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18Z NAM coming in warmer than the 12Z run. It doesn't seem to want to cave into the colder globals and has a sleet fest getting into CNE and is rain for all of SNE outside of the northern Berks by 09Z Thursday. Either it's on to something or it's going to bust very badly. Unless, the 18Z GFS and the rest of the 00Z suite suddenly give in, the NAM is going to bust very badly. I will continue to ride the colder consensus for now.

One aspect of this run that is odd looking for me is that the NAM places it's 850mb closed center over CT, but all the QC forcing is well SE of there associated with the tracking V-Max... Not sure the model is going to be entirely successful with that -

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Euro and Euro trending colder on 12z runs today should be the deal sealer. We needed that to happen to lock in the colder solutions winning out. I have a hard time seeing anwhere north of a line from say HVN to IJD to PVD get above 32,,until you're to 495

Easterly flow torches the coast. HVN will be 40 Thursday morning. You may be below 32 throughout though. Or like 33-34.

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Easterly flow torches the coast. HVN will be 40 Thursday morning. You may be below 32 throughout though. Or like 33-34.

Westerly flow torches us too. Some of the warmest surface temps occur in the 3 hrs after 850mb temps start cooling, especially in the CT Valley. where they get down sloping.

I remember one event in 1998 where HPN torched to 38 and New Haven stayed ZR. It was a bizarre year.

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Easterly flow torches the coast. HVN will be 40 Thursday morning. You may be below 32 throughout though. Or like 33-34.

If the surface tracks further south and exits under NYC as the 12z Euro shows, you don't have as much easterly flow and winds are much more ENE/NE, which limits boundary layer warming. That's going to be the key difference for areas near the coast in getting a significant front-end dump versus a slop event: if winds are NE, the cold 850s allow the storm to be mostly snow. If winds veer east, then you have marine contamination and it is mostly rain. What interests me is a sharp gradient in surface temperatures running from HPN to HVN and potentially very heavy snow just ahead of that mix line. Watching this one closely in Westchester for sure, with vacation house in Poconos an option.

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If the surface tracks further south and exits under NYC as the 12z Euro shows, you don't have as much easterly flow and winds are much more ENE/NE, which limits boundary layer warming. That's going to be the key difference for areas near the coast in getting a significant front-end dump versus a slop event: if winds are NE, the cold 850s allow the storm to be mostly snow. If winds veer east, then you have marine contamination and it is mostly rain. What interests me is a sharp gradient in surface temperatures running from HPN to HVN and potentially very heavy snow just ahead of that mix line. Watching this one closely in Westchester for sure, with vacation house in Poconos an option.

Yeah, but the antecedent air mass if ok at best, so any marine influence whatsoever flips the coast. But yeah, if the euro solution occurs, it'll be below 32F for many in interior CT with S+ to IP/ZR with a snow thump at coast to 35F HVN/40F GON RA+

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Yeah, again, not sure if you guys saw my post about to wxmanmitch, but nne aspect of this run that is odd looking for me is that the NAM places it's 850mb closed center over CT, but all the QC forcing is well SE of there associated with the tracking V-Max... Not sure the model is going to be entirely successful with that - this run, and the 12z for that matter are suspect due to this odd construction of the deep layer vortex.

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Yeah, but the antecedent air mass if ok at best, so any marine influence whatsoever flips the coast. But yeah, if the euro solution occurs, it'll be below 32F for many in interior CT with S+ to IP/ZR with a snow thump at coast to 35F HVN/40F GON RA+

Do you think I go to all rain in the 300-400' elevation band here in Westchester? Or can we hold on to mostly snow and sleet with just some drizzle towards the end?

The antecedent airmass, while not as cold as the airmasses we're going to see after this storm, is not terrible. I'm supposed to get down in the mid 20s tonight about 25 miles north of NYC. Dewpoints are upper 20s near the coast here.

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AWT..Watches have been expanded..

.WINTER STORM WATCH IN EFFECT FROM WEDNESDAY EVENING THROUGH

LATE THURSDAY NIGHT...

THE NATIONAL WEATHER SERVICE IN TAUNTON HAS ISSUED A WINTER STORM

WATCH...WHICH IS IN EFFECT FROM WEDNESDAY EVENING THROUGH THURSDAY

NIGHT.

* HAZARD TYPES...HEAVY SNOW WITH THE POSSIBILITY OF SLEET AND

FREEZING RAIN.

* TIMING...STARTING WEDNESDAY NIGHT AROUND 7 PM.

* ACCUMULATIONS...SNOW ACCUMULATION OF 4 TO 8 INCHES...ALONG WITH

ICE.

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AWT..Watches have been expanded..

.WINTER STORM WATCH IN EFFECT FROM WEDNESDAY EVENING THROUGH

LATE THURSDAY NIGHT...

THE NATIONAL WEATHER SERVICE IN TAUNTON HAS ISSUED A WINTER STORM

WATCH...WHICH IS IN EFFECT FROM WEDNESDAY EVENING THROUGH THURSDAY

NIGHT.

* HAZARD TYPES...HEAVY SNOW WITH THE POSSIBILITY OF SLEET AND

FREEZING RAIN.

* TIMING...STARTING WEDNESDAY NIGHT AROUND 7 PM.

* ACCUMULATIONS...SNOW ACCUMULATION OF 4 TO 8 INCHES...ALONG WITH

ICE.

Still think my 4-7" looks good for you. Congrats

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AWT..Watches have been expanded..

.WINTER STORM WATCH IN EFFECT FROM WEDNESDAY EVENING THROUGH

LATE THURSDAY NIGHT...

THE NATIONAL WEATHER SERVICE IN TAUNTON HAS ISSUED A WINTER STORM

WATCH...WHICH IS IN EFFECT FROM WEDNESDAY EVENING THROUGH THURSDAY

NIGHT.

* HAZARD TYPES...HEAVY SNOW WITH THE POSSIBILITY OF SLEET AND

FREEZING RAIN.

* TIMING...STARTING WEDNESDAY NIGHT AROUND 7 PM.

* ACCUMULATIONS...SNOW ACCUMULATION OF 4 TO 8 INCHES...ALONG WITH

ICE.

Note the verbiage of the locations. Ive got a watch up here too, yet the location doesnt mention Ct! ??

Tolland

Forecasts for Connecticut — Return to U.S. Severe Weather headerBlue-left.gif Current Severe Weather headerBlue-right.gifsubBlue-left.gifsubBlue-right.gif

WIN.gif Winter Storm Watch WIN.gif

Statement as of 4:09 PM EST on December 25, 2012

... Winter Storm Watch in effect from Wednesday evening through

late Thursday night...

The National Weather Service in Taunton has issued a Winter Storm

Watch... which is in effect from Wednesday evening through Thursday

night.

* Locations... portions of western and northern Massachusetts...

including southern New Hampshire.

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Do you think I go to all rain in the 300-400' elevation band here in Westchester? Or can we hold on to mostly snow and sleet with just some drizzle towards the end?

The antecedent airmass, while not as cold as the airmasses we're going to see after this storm, is not terrible. I'm supposed to get down in the mid 20s tonight about 25 miles north of NYC. Dewpoints are upper 20s near the coast here.

I think you eek out a nice thump if you're NW of HPN (I assume you are). But, most will have taint in SNE and adjacent NY because of the MSLP position over or just south of LI (model consensus). You'll probably get 2-5" then sleet...and eventually like 36F rain or something. Just a gut feeling.

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