NYC/PHL Potential Jan 11-14 Event Discussion Part Two

[NickD2011]

Let's continue discussion here!

[Manny]

All guidance coming in line with moderate snow for Wednesday, but whether it's significant, or major hit for the coast is still up in the air.

[gkrangers]

18z GFES at 84

[unknown]

RUC has both S/W much closer compared to NAM

NAM

RUC

[Thunder Road]

RUC has both S/W much closer compared to NAM

NAM

RUC

We have a pretty good idea of how the s/w will act, the question is in just how far south the norther stream digs.

[unknown]

Also 500mb vort shows a stronger S/W, which alows more digging and phasing with southern S/W

RUC

NAM

[hudsonvalley21]

BTW, the speed of the 18z GFS looks to be ridiculously fast for a 3 countour closed h500 low, stacked with the lower levels.....watch for a slowing trend in future outputs.

Intersting post from LEK in the Upstate NY thread "Jan 11th-12th Snow threat." I wanted to put in this thread.

[A-L-E-X]

Intersting post from LEK in the Upstate NY thread I wanted to put in this thread.

Jibes well with what Upton said in terms of a slower storm (with a lot of wind) like what the Euro depicted.

[hudsonvalley21]

Jibes well with what Upton said in terms of a slower storm (with a lot of wind) like what the Euro depicted.

Definitley raises both eyebrows intsead of one.

[NickD2011]

The latest DGEX shows .75-1.25 QPF for the entire region, with the higher end up north

[A-L-E-X]

Definitley raises both eyebrows intsead of one.

Yeah, that and Will's comparison to March 1960. I've always wanted to see a storm like that.

[Chris L]

Yeah, that and Will's comparison to March 1960. I've always wanted to see a storm like that.

Pick one: March 1960 or December 1960?

In seriousness, the key feature is the H500 low and see if it closes off faster rather than too late.

[forkyfork]

sref tracks

[Tiburon]

BTW, 18Z NAM shows PHL staying below 0C at all layers through 84 hours with .30" QPF. KMIV (Millville, NJ) goes above 0C between 800mb and 850 (Tmax = 0.4C) at hour 78. So interior southern NJ looks ok even on the 18Z NAM.

[tombo82685]

BTW, 18Z NAM shows PHL staying below 0C at all layers through 84 hours with .30" QPF. KMIV (Millville, NJ) goes above 0C between 800mb and 850 (Tmax = 0.4C) at hour 78. So interior southern NJ looks ok even on the 18Z NAM.

the snow growth is very blah for i 95 south...you get up towards abe the omega in the snow growth region is nuts.

[dwang0725]

the snow growth is very blah for i 95 south...you get up towards abe the omega in the snow growth region is nuts.

Tom, great point. Soundings alone will not tell the whole story. Bufkit is your friend.

[Edge Weather]

Tom, I know it is probably too early, but based upon what you are seeing, what would the projected snow ratios be for this storm in the ABE / NW NJ region?

the snow growth is very blah for i 95 south...you get up towards abe the omega in the snow growth region is nuts.

[Edge Weather]

Would you be able to provide a link as to where you are getting your Bufkit readings?

Tom, great point. Soundings alone will not tell the whole story. Bufkit is your friend.

[goldstar]

Can u link me the panel or page that shows the snow growth trends etc?

[tombo82685]

Tom, I know it is probably too early, but based upon what you are seeing, what would the projected snow ratios be for this storm in the ABE / NW NJ region?

i wasn't looking at the bufkit i was looking at the omega, UVV's in the snow growth region....ill post what im saying

phl nam

abe nam

[tombo82685]

Would you be able to provide a link as to where you are getting your Bufkit readings?

heres the bufkit

http://www.meteor.iastate.edu/~ckarsten/bufkit/data/index.html

[earthlight]

There have been a slew of questions and posts over the past day or so regarding the "lack of precipitation" or "lack of QPF" on the models. First of all, I think the statement in itself is flawed. Most people here are probably looking for 2"+ QPF bombs we have been seeing so far this winter. Truth is, that won't happen here..we don't have the insane dynamics, phasing, and 970's mb surface low that we did with the last system. Everybody should try and do their best to get those numbers out of their heads. The fact is that 1" liquid is a significant winter storm and there are plenty of models heading towards those numbers.

Still, plenty have asked why the models are taking so long to develop the heavy precipitation. The problem lies in the initial surface low and initial 500mb flow. I included the 18z NAM depiction at 72 hours in a below image with the H5, SLP, and 6 hr QPF chart. There are several things to note here. First, the primary low into the Ohio Valley. This primary low is being driven by the initial burst of 500mb vorticity which you can see at the time over Southern Illinois. The secondary surface low is still forming over the Carolinas. Usually, we would have more significant precipitation associated with this feature. But the H5 forcing is still lagging back to the west. There is a favorable diffluent flow with the ridge axis over the East coast--which will help form the surface low northward and eventually develop the CCB. But we aren't going to get prolific amounts until that said cold conveyor belt can really develop and mature.

The details go beyond this though, as I mentioned how things should really get going once the dynamics come into play. I included the NAM high resolution graphics of the 250mb jet stream at the same valid time below. That's a 120kt 250mb jet streak already ejecting northeast out of the base of the trough towards the East coast. It doesn't really matter how strong the primary is, once that gets in play (it's not just at 250mb either, as we all know) things should really get going.

The other thing I wanted to hit on really quickly, without getting into too many details at this range, is the potential for banding. The NAM, as an example, is rapidly developing the cold conveyor belt and is bringing an area of enhanced frontogenic forcing up along the coast and into New Jersey and towards the Northern Mid Atlantic including Eastern PA, eventually NYC, etc. This could, as we all know, be an area where prolific snow amounts are recorded. The NAM in it's own right would advertise the potential for dynamic heavy wet snow..and the potential for thundersnow once again within the banding area. Here's the H7 vertical velocities below which show the rather broad area of support for heavy snow (as evidenced by the NCEP H7 UVV charts as well)..but a small area where very intense snowfall rates would be occurring at that time as well. There are also intense 850mb vertical velocities moving northeast over coastal NJ and towards LI/NYC at that time frame. The H85 low reforming and the surface low deepening rapidly just off the coast would likely create a prolific snow event even towards the coast despite some initial warmth.

So in general, there is really some dynamic potential here. As far as the models and their QPF..there are reasons why they haven't showed absolutely prolific amounts--and I wouldn't expect them with this type of event, either. But if the guidance trends are any indication, and this storm is going to tuck off the coast as depicted, somebody is going to get slammed with some prolific amounts underneath heavy frontogenic forcing and banding. Exciting possibilities here as we sit 78-84 hours away from the event.

[Edge Weather]

Thank you, although I have absolutely no clue what I am looking at to be honest.

i wasn't looking at the bufkit i was looking at the omega, UVV's in the snow growth region....ill post what im saying

phl nam

abe nam

[Edge Weather]

Thank you Tom. I very much appreciate your help and your fantastic job with the Euro for everyone here. You are amazing.

heres the bufkit

http://www.meteor.ia...data/index.html

[Allsnow]

There have been a slew of questions and posts over the past day or so regarding the "lack of precipitation" or "lack of QPF" on the models. First of all, I think the statement in itself is flawed. Most people here are probably looking for 2"+ QPF bombs we have been seeing so far this winter. Truth is, that won't happen here..we don't have the insane dynamics, phasing, and 970's mb surface low that we did with the last system. Everybody should try and do their best to get those numbers out of their heads. The fact is that 1" liquid is a significant winter storm and there are plenty of models heading towards those numbers.

Still, plenty have asked why the models are taking so long to develop the heavy precipitation. The problem lies in the initial surface low and initial 500mb flow. I included the 18z NAM depiction at 72 hours in a below image with the H5, SLP, and 6 hr QPF chart. There are several things to note here. First, the primary low into the Ohio Valley. This primary low is being driven by the initial burst of 500mb vorticity which you can see at the time over Southern Illinois. The secondary surface low is still forming over the Carolinas. Usually, we would have more significant precipitation associated with this feature. But the H5 forcing is still lagging back to the west. There is a favorable diffluent flow with the ridge axis over the East coast--which will help form the surface low northward and eventually develop the CCB. But we aren't going to get prolific amounts until that said cold conveyor belt can really develop and mature.

The details go beyond this though, as I mentioned how things should really get going once the dynamics come into play. I included the NAM high resolution graphics of the 250mb jet stream at the same valid time below. That's a 120kt 250mb jet streak already ejecting northeast out of the base of the trough towards the East coast. It doesn't really matter how strong the primary is, once that gets in play (it's not just at 250mb either, as we all know) things should really get going.

The other thing I wanted to hit on really quickly, without getting into too many details at this range, is the potential for banding. The NAM, as an example, is rapidly developing the cold conveyor belt and is bringing an area of enhanced frontogenic forcing up along the coast and into New Jersey and towards the Northern Mid Atlantic including Eastern PA, eventually NYC, etc. This could, as we all know, be an area where prolific snow amounts are recorded. The NAM in it's own right would advertise the potential for dynamic heavy wet snow..and the potential for thundersnow once again within the banding area. Here's the H7 vertical velocities below which show the rather broad area of support for heavy snow (as evidenced by the NCEP H7 UVV charts as well)..but a small area where very intense snowfall rates would be occurring at that time as well. There are also intense 850mb vertical velocities moving northeast over coastal NJ and towards LI/NYC at that time frame. The H85 low reforming and the surface low deepening rapidly just off the coast would likely create a prolific snow event even towards the coast despite some initial warmth.

So in general, there is really some dynamic potential here. As far as the models and their QPF..there are reasons why they haven't showed absolutely prolific amounts--and I wouldn't expect them with this type of event, either. But if the guidance trends are any indication, and this storm is going to tuck off the coast as depicted, somebody is going to get slammed with some prolific amounts underneath heavy frontogenic forcing and banding. Exciting possibilities here as we sit 78-84 hours away from the event.

wow what a post...very nice

[tombo82685]

Thank you, although I have absolutely no clue what I am looking at to be honest.

for good snow growth you want the higher neg numbers, or deeper colors like blues and purples and pinks, in the 700mb zone, this is the snow growth region.

[SnowGoose69]

The #1 CIPS analog in the eastern region at 72 hours is 1/7/96...the OH Valley region shows 02/09/2010, 12/05/02 and 12/25/02

[Edge Weather]

How do you get snowfall totals from the Bufkit readings? Where do I look in that long list of stuff?

heres the bufkit

http://www.meteor.ia...data/index.html

[tombo82685]

How do you get snowfall totals from the Bufkit readings? Where do I look in that long list of stuff?

check the northeast box, then click the station bubble closest to you.

[Tiburon]

the snow growth is very blah for i 95 south...you get up towards abe the omega in the snow growth region is nuts.

Tom, great point. Soundings alone will not tell the whole story. Bufkit is your friend.

I'm not really disputing that, Tom. I was actually responding to a poster in the first thread who was mentioning p-type issues east of I-95 around PHL. This isn't our storm, not this time. We'll get a nice little snowfall out of it. If I had a gun to my head, I'd say 4-8" right about now, but I'm going to wait to see how the remaining suites look before making my mind up.