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NEG NAO

March 13 - 15 Major Winter Storm Potential

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16 minutes ago, JetsPens87 said:

Greetings all

It's been awhile since I came out of the woodwork to write thoughts on a storm although I read daily. But I have so many thoughts on this one that I felt the need to jump in and maybe bring some food for thought to the table.

I have noticed a few things that I need to point out. First, this is a very potent late season system with a ton of energy and ample cold air supply. However, there are a few major hiccups that in my opinion will hold it back from being the true monster that could have developed (and was being earlier advertised by some models).

First, I must strongly urge caution in looking at the surface low and wishing for it to move one way or the other. The true tale of what is going on lies in the middle levels. Let me point out an image that should urge caution.

 

gfs_z700_vort_us_13.png

The lack of precip on the NW side on the gfs in my opinion is a result of what is occurring at the mid levels. That second interior mid level low closing off over WPA provides for an area of subsidence in between itself and the developing coastal.

 

gfs_mslp_pwata_us_11.png

All looks well until....

 

gfs_mslp_pwata_us_13.png

That mid level low over Pitt essentially shuts off the firehose flowing in off the Atlantic. To me this is a direct result of the trend in the models that has been consistent for the past 36 hours in a later sloppier phase and a much quicker moving system. While the surface reflection may be "chasing" convection offshore, I think the more worrisome factor is what I am seeing at the mid levels. Now with that said, I do believe that there will be an area in that precip shield that will be more intense than what models are advertising due to the poor surface reflection being modeled at this point and I believe the ensembles (both the GEFS/EPS) agree on that.

I strongly strongly urge against getting hung up in snowfall maps and even QPF outputs a this juncture and focus at this lead time on what is occurring upstairs, "weather" afterall starts in the mid levels and anything else is a byproduct of that function. If we see any slowing down occurring than I think we could be back in the game for a really big storm, but with the consistent trends recently on a sloppier later phase and a faster system, I think the coastal plain is relying on an initial "front end thump" based off dynamics rather than a raging CCB, the same statement does not hold true further north where I do believe the system gets fully cranking and rips a CCB, though that area is yet to be fully nailed down and the HI RES models once into more accurate range can help to begin pinpoint that. If you had to ask me right now I would see the greatest impacts would be NNJ, SENY, and into greater New England, with a very sharp cutoff immediately beyond that due to the mid level presentation right now,

I welcome all questions, comments and discussion.

Sage advice and nice handle.  

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20 minutes ago, JetsPens87 said:

Greetings all

It's been awhile since I came out of the woodwork to write thoughts on a storm although I read daily. But I have so many thoughts on this one that I felt the need to jump in and maybe bring some food for thought to the table.

I have noticed a few things that I need to point out. First, this is a very potent late season system with a ton of energy and ample cold air supply. However, there are a few major hiccups that in my opinion will hold it back from being the true monster that could have developed (and was being earlier advertised by some models).

First, I must strongly urge caution in looking at the surface low and wishing for it to move one way or the other. The true tale of what is going on lies in the middle levels. Let me point out an image that should urge caution.

 

gfs_z700_vort_us_13.png

The lack of precip on the NW side on the gfs in my opinion is a result of what is occurring at the mid levels. That second interior mid level low closing off over WPA provides for an area of subsidence in between itself and the developing coastal.

 

gfs_mslp_pwata_us_11.png

All looks well until....

 

gfs_mslp_pwata_us_13.png

That mid level low over Pitt essentially shuts off the firehose flowing in off the Atlantic. To me this is a direct result of the trend in the models that has been consistent for the past 36 hours in a later sloppier phase and a much quicker moving system. While the surface reflection may be "chasing" convection offshore, I think the more worrisome factor is what I am seeing at the mid levels. Now with that said, I do believe that there will be an area in that precip shield that will be more intense than what models are advertising due to the poor surface reflection being modeled at this point and I believe the ensembles (both the GEFS/EPS) agree on that.

I strongly strongly urge against getting hung up in snowfall maps and even QPF outputs a this juncture and focus at this lead time on what is occurring upstairs, "weather" afterall starts in the mid levels and anything else is a byproduct of that function. If we see any slowing down occurring than I think we could be back in the game for a really big storm, but with the consistent trends recently on a sloppier later phase and a faster system, I think the coastal plain is relying on an initial "front end thump" based off dynamics rather than a raging CCB, the same statement does not hold true further north where I do believe the system gets fully cranking and rips a CCB, though that area is yet to be fully nailed down and the HI RES models once into more accurate range can help to begin pinpoint that. If you had to ask me right now I would see the greatest impacts would be NNJ, SENY, and into greater New England, with a very sharp cutoff immediately beyond that due to the mid level presentation right now,

I welcome all questions, comments and discussion.

As a professional writer I must say your sense of syntax, punctuation and rhythem are only beaten by the lucidity of your scientific argument. having said : I know by 0 Z we will have info from the actual system ingested into the models and as such have a clearer picture but the real question here is what will be the most important factor in helping for a faster phase in your opinion. I know that fire hose presentation, and have seen signs of it on a couple of the models but i fyou are saying the pit Uppe rlow shuts that off, tbh, March 2001 comes to mind. We were projected to get to 24-36 but , as Im sure, you remember the transfer happened too late for NYC and points SE. Ill accept disappointment so long as I see it coming . Appreciate both your time and effort.

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4 minutes ago, nyblizz44 said:

As a professional writer I must say your sense of syntax, punctuation and rhythem are only beaten by the lucidity of your scientific argument. having said : I know by 0 Z we will have info from the actual system ingested into the models and as such have a clearer picture but the real question here is what will be the most important factor in helping for a faster phase in your opinion. I know that fire hose presentation, and have seen signs of it on a couple of the models but i fyou are saying the pit Uppe rlow shuts that off, tbh, March 2001 comes to mind. We were projected to get to 24-36 but , as Im sure, you remember the transfer happened too late for NYC and points SE. Ill accept disappointment so long as I see it coming . Appreciate both your time and effort.

I don't think it's like March 2001 because the phase clearly happens. It's just a question of how much energy remains behind in the Midwest, and whether that vort disrupts the inflow into the developing coastal. We'd like to see a cleaner, earlier phase. The east trend is mostly due to the lack of a true, full phase with the PV energy to the northwest.

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12 minutes ago, nyblizz44 said:

As a professional writer I must say your sense of syntax, punctuation and rhythem are only beaten by the lucidity of your scientific argument. having said : I know by 0 Z we will have info from the actual system ingested into the models and as such have a clearer picture but the real question here is what will be the most important factor in helping for a faster phase in your opinion. I know that fire hose presentation, and have seen signs of it on a couple of the models but i fyou are saying the pit Uppe rlow shuts that off, tbh, March 2001 comes to mind. We were projected to get to 24-36 but , as Im sure, you remember the transfer happened too late for NYC and points SE. Ill accept disappointment so long as I see it coming . Appreciate both your time and effort.

There are always many things that can go wrong with setups like these, hence them being so rare. My expectation is for a nice but not epic event, and given its March, all the better. The people I feel bad for are the Appalachian spine crew who looked at a really good event and now is looking at another shafting. That area's been deprived for way too long.

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35 minutes ago, nzucker said:

I don't think it's like March 2001 because the phase clearly happens. It's just a question of how much energy remains behind in the Midwest, and whether that vort disrupts the inflow into the developing coastal. We'd like to see a cleaner, earlier phase. The east trend is mostly due to the lack of a true, full phase with the PV energy to the northwest.

This is an interesting comparison, though I hesitate to use "interesting" when referring to that storm haha. It still sticks in my memory like it was yesterday.

Anyway, I agree here that it differs slightly from 01' in that as you say it's less of a lack of transfer to the coast (as that seemingly happens quite early) and more a lack of a cleaner earlier phase with a slower system as was advertised earlier in the game. Could that still occur? Absolutely, as could any one of a number of outcomes. However, if I had to guess I would have to favor the later sloppier phase. There are a number of factors that could implicate that as the case. The strongly positive NAO is certainly one of them, had that blocking been stronger, than this could have had the time to consolidate quicker.

13 minutes ago, Stormlover74 said:

Do you think Upton is being too bullish in forecasting widespread 12-18" particularly beyond 48 hours?

I always hesitate to question the wisdom of the NWS and I believe they have made a reasonable call given everything on the table. 12-18 provides them some wiggle room on either side to adjust within a reasonable range without it being too dramatic of a shift and without too dramatic of a shift in public perception. Think for example if they eventually lower to say 8-12 or up to 16-24, there is little perception change in the public's reaction to either of those adjustments. Had they forecast on the other hand 18-24" only to have the current model depictions continue or hold true and adjusted downward all the way to 8-12" that would be a major blow to their mission. Vice versa, had they come out and forecast 6-12", the point may not have gotten across just how impactful this system could be, only to have to up amounts way late in the game if that case became true.

While their forecast in my opinion is quite bullish at this lead time, I believe it was the best way to go and affords them some flexibility without damaging their mission and without drastic changes in the public perception of what is unfolding.

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28 minutes ago, jm1220 said:

There are always many things that can go wrong with setups like these, hence them being so rare. My expectation is for a nice but not epic event, and given its March, all the better. The people I feel bad for are the Appalachian spine crew who looked at a really good event and now is looking at another shafting. That area's been deprived for way too long.

Im happy to spread the wealth, another PD II or Jan 96 would be just fine with me :D

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39 minutes ago, nzucker said:

I don't think it's like March 2001 because the phase clearly happens. It's just a question of how much energy remains behind in the Midwest, and whether that vort disrupts the inflow into the developing coastal. We'd like to see a cleaner, earlier phase. The east trend is mostly due to the lack of a true, full phase with the PV energy to the northwest.

Very helpful response. thx a bunch!

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51 minutes ago, nyblizz44 said:

As a professional writer I must say your sense of syntax, punctuation and rhythem are only beaten by the lucidity of your scientific argument. having said : I know by 0 Z we will have info from the actual system ingested into the models and as such have a clearer picture but the real question here is what will be the most important factor in helping for a faster phase in your opinion. I know that fire hose presentation, and have seen signs of it on a couple of the models but i fyou are saying the pit Uppe rlow shuts that off, tbh, March 2001 comes to mind. We were projected to get to 24-36 but , as Im sure, you remember the transfer happened too late for NYC and points SE. Ill accept disappointment so long as I see it coming . Appreciate both your time and effort.

In my opinion the biggest factor preventing the earlier phase is the lack of strong blocking at the higher latitudes. However, at almost +2 in the NAO region, that is most likely a factor that is not going to change in our favor. The factor that could change in our favor would be slightly more PNA ridging. This could help the northern stream energy push farther into the system and consolidate a bit sooner. We have been running our luck in recent years relying on PNA and EPO domain blocking and been making out pretty well for it.

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2 minutes ago, psv88 said:

SREFS are wet. 1.50 for much of this board

I'll never forget the Jan 15 srefs 21z night before storm... 2-3" LE... flurries... I'm cautious with this storm up here... bust potential is huge north And west of rockland county IMO

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Just now, UlsterCountySnowZ said:

I'll never forget the Jan 15 srefs 21z night before storm... 2-3" LE... flurries... I'm cautious with this storm up here... bust potential is huge north And west of rockland county IMO

I agree. I wouldnt expect much if i were you...maybe 4-8", if you get 18", great...

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1 minute ago, UlsterCountySnowZ said:

I'll never forget the Jan 15 srefs 21z night before storm... 2-3" LE... flurries... I'm cautious with this storm up here... bust potential is huge north And west of rockland county IMO

Ulster, what was the LE potential predicted for the 3/2001 non event ?

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1 minute ago, UlsterCountySnowZ said:

I'll never forget the Jan 15 srefs 21z night before storm... 2-3" LE... flurries... I'm cautious with this storm up here... bust potential is huge north And west of rockland county IMO

Not having the gfs or rgem was a huge red flag, plus we lost the nam in the final 24 hours as well

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1 minute ago, UlsterCountySnowZ said:

I'll never forget the Jan 15 srefs 21z night before storm... 2-3" LE... flurries... I'm cautious with this storm up here... bust potential is huge north And west of rockland county IMO

It's a March storm, so bust potential is there no matter what. Seen a lot of busts in March, though none as epic as 2001...in fact 93 was quite the anomaly and at the time it was shocking.

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2 minutes ago, F5TornadoF5 said:

Surface low in ideal location on srefs. Fwiw this far out.

IMG_0961.GIF

Looks fairly similar to other guidance, too bad we can't see 500, it's clearly not supressing the energy and closing off the firehose to allow for an expansive western shield of heavier precip 

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18 minutes ago, JetsPens87 said:

In my opinion the biggest factor preventing the earlier phase is the lack of strong blocking at the higher latitudes. However, at almost +2 in the NAO region, that is most likely a factor that is not going to change in our favor. The factor that could change in our favor would be slightly more PNA ridging. This could help the northern stream energy push farther into the system and consolidate a bit sooner. We have been running our luck in recent years relying on PNA and EPO domain blocking and been making out pretty well for it.

Yes it's a shame because we had such great -NAO blocking for the first time all winter just a few days ago.

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19 minutes ago, JetsPens87 said:

In my opinion the biggest factor preventing the earlier phase is the lack of strong blocking at the higher latitudes. However, at almost +2 in the NAO region, that is most likely a factor that is not going to change in our favor. The factor that could change in our favor would be slightly more PNA ridging. This could help the northern stream energy push farther into the system and consolidate a bit sooner. We have been running our luck in recent years relying on PNA and EPO domain blocking and been making out pretty well for it.

That NAO was the bugaboo I feared, I know Kocin storms are rare beasts. Lets us see what 0 Z has in store for us, we should have a better idea in 4.5 hours. If the Euro trends east again I think many of us will prepare mentally for a reduction in expectations. Thanks a lot for clarifying and GO PNA+++ :D

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Just now, nyblizz44 said:

That NAO was the bugaboo I feared, I know Kocin storms are rare beasts. Lets us see what 0 Z has in store for us, we should have a better idea in 4.5 hours. If the Euro trends east again I think many of us will prepare mentally for a reduction in expectations. Thanks a lot for clarifying and GO PNA+++ :D

All 00z suites should have NHC southern stream sampling 

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Just now, nyblizz44 said:

That NAO was the bugaboo I feared, I know Kocin storms are rare beasts. Lets us see what 0 Z has in store for us, we should have a better idea in 4.5 hours. If the Euro trends east again I think many of us will prepare mentally for a reduction in expectations. Thanks a lot for clarifying and GO PNA+++ :D

With the extra data being ingested into the models for the 0z suite tonight we should have a clearer picture like you said and I'll be very interested to see which way the upper and mid levels trend versus earlier data. If things look a little cleaner than that is a really good sign, however if we see a continued disruption in the mid level presentation I would begin to worry more.

Like I said, this evening I would be more concerned with seeing what happens with things like 500mb vort, 500mb heights, 750 vort and 750 RH% rather than QPF and snowfall maps.

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Just now, Violentweatherfan said:

Did the models two days ago take in account of the +2 that is occurring now?

Yes they would have taken into account the rising NAO. However, to put it in better terms, they were at that point forecasting the NAO further out than they are now. So at shorter lead times we should have a more accurate reflection of the impact of the NAO. It appeared days ago that all the energy would have consolidated sooner and had a slower moving system. As the lead time shortens we are getting a more accurate reflection of the pieces of energy in play and how the rest of the global system reflects that.

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2 minutes ago, Violentweatherfan said:

Did the models two days ago take in account of the +2 that is occurring now?

 

2 minutes ago, Violentweatherfan said:

Did the models two days ago take in account of the +2 that is occurring now?

Won't the +NAO keep this from moving slow? The faster it is, the less the accumulations, I've learned that much over the years

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5 minutes ago, JetsPens87 said:

With the extra data being ingested into the models for the 0z suite tonight we should have a clearer picture like you said and I'll be very interested to see which way the upper and mid levels trend versus earlier data. If things look a little cleaner than that is a really good sign, however if we see a continued disruption in the mid level presentation I would begin to worry more.

Like I said, this evening I would be more concerned with seeing what happens with things like 500mb vort, 500mb heights, 750 vort and 750 RH% rather than QPF and snowfall maps.

Great posts tonight - very informative.  The other key thing is that, if I recall correctly, the key piece of energy is now over land in the NW and we should have a better input data set, which, as I know you know is absolutely critical to reducing the error propagation over time inherent in chaotic systems.  

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7 minutes ago, JetsPens87 said:

With the extra data being ingested into the models for the 0z suite tonight we should have a clearer picture like you said and I'll be very interested to see which way the upper and mid levels trend versus earlier data. If things look a little cleaner than that is a really good sign, however if we see a continued disruption in the mid level presentation I would begin to worry more.

Like I said, this evening I would be more concerned with seeing what happens with things like 500mb vort, 500mb heights, 750 vort and 750 RH% rather than QPF and snowfall maps.

Here's a question:  What are you actually looking at with the 500mb maps?  What do they represent in other words?

Also, Ulster mentioned the NHC.  What sort of data does the NHC collect for these storms?

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1 minute ago, weatherpruf said:

 

Won't the +NAO keep this from moving slow? The faster it is, the less the accumulations, I've learned that much over the years

Yes, it certainly will. To get a quicker, cleaner phase we would need a greater spike in the PNA, though at that point without the -NAO it would still be a fairly quick moving system.

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5 minutes ago, JetsPens87 said:

Yes they would have taken into account the rising NAO. However, to put it in better terms, they were at that point forecasting the NAO further out than they are now. So at shorter lead times we should have a more accurate reflection of the impact of the NAO. It appeared days ago that all the energy would have consolidated sooner and had a slower moving system. As the lead time shortens we are getting a more accurate reflection of the pieces of energy in play and how the rest of the global system reflects that.

Thanks, now I see why you are leaning towards the latter in your previous post.

I think  there is another check box to add to the KU list, is the blocking/-NAO continuous throughout the storm timeframe.

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