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NYC/Tri-State Area: Stumbling into January Disco


earthlight

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Surface temps of 35-40 degrees (it begins with temps in the 40's). 850's are barely below 0.

It's better to look at critical thickness values (the so-called "540 line") or 850mb temperatures, both of which are OK in this set-up, when talking about longer-range events. It doesn't matter anyway though since it's the 18z DGEX and unlikely to happen.

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It's better to look at critical thickness values (the so-called "540 line") or 850mb temperatures, both of which are OK in this set-up, when talking about longer-range events. It doesn't matter anyway though since it's the 18z DGEX and unlikely to happen.

True, but looking at the DGEX verbatim, it would be difficult to get snow with surface temps around 40 and with the air aloft barely supportive of snow.

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True, but looking at the DGEX verbatim, it would be difficult to get snow with surface temps around 40 and with the air aloft barely supportive of snow.

It is really stupid to argue about the DGEX ( especially 156 hours out ). Looks like this run shows mid 30's for NYC with snow.

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It is really stupid to argue about the DGEX ( especially 156 hours out ). Looks like this run shows mid 30's for NYC with snow.

Yes your right we are talking about the difference between wet snow that doesn't stick and rain on a DGEX run that probably won't verify anyway.

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Temps are in the 40's before the precip starts falling, and 850's are very marginal. It would definitely start as rain and maybe transition to snow towards the end of the precip:

f150.gif

Def starts as rain. I was referring to the frame you posted. But we are talking about the dgex which isn't really worth much.

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dgex is a glorified swfe that is marginally cold for snow and will likely trend warmer and wetter. even the nogaps is wrapped up and rain.

How is the NOGAPS rain?

2 meter temps

850 temps

My whole point of posting it mainly was to show that it potentially red flags the GFS for being to far to the east but then also as well it potentially says that it could end up west from there.

But i do not think that this would be rain with the temperatures shown the way that they are..the danger lies in if the bias is correct this could come more west and THAT is how the area could end up with rain...

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With the AR possibly splitting and moving north, the ao relaxing......looks like we are indeed headed to a true nina gradient pattern with cold air across the west spilling over into the northeast. With a robust se ridge I would have to imagine any boundary would be very close to the region, I dont think anyone is safe, plenty of joy and heartbreak on the way

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How is the NOGAPS rain?

2 meter temps

850 temps

My whole point of posting it mainly was to show that it potentially red flags the GFS for being to far to the east but then also as well it potentially says that it could end up west from there.

But i do not think that this would be rain with the temperatures shown the way that they are..the danger lies in if the bias is correct this could come more west and THAT is how the area could end up with rain...

well, i just assumed it was too far east, i.e its gonna correct west, which it probably is with no blocking.

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well, i just assumed it was too far east, i.e its gonna correct west, which it probably is with no blocking.

I think the flow is a bit too fast to allow for much of a correction west, assuming the shortwave does not cut off over the Southern US. The ridge over the Western US and Rockies collapses to the east a bit, and the jet stream almost flattens. Additionally the baroclinic zone is pushed pretty far offshore by the storm system passing to our north a few days prior. If you loop the 18z GFS, you can see how the ridge is pressing on the pattern a good bit. If the shortwave cuts off, it is an entirely different ballgame as it can wait for the next big/amplified northern stream feature which will phase and bring the surface low inland.

Again, the window for this to produce snow for us is so incredibly small -- I do think it is worth a look, though.

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The tail end of the GEFS super ensemble and ECMWF ensembles offer some quickly increasing support for a very active pattern dominated by a -PNA and -EPO. Such an atmospheric regime would support a developing gradient type pattern (I know we hear this a lot, but this is almost a classic case of one) which can sometimes bring prolific snows north of the thermal gradient. It is important to notice two relatively dominant features on the super ensembles -- first a huge Pacific and Aleutian ridge which extends all the way to the Pole. Also notice the extension of the ridge over Western Greenland. Second, an increasingly large and expansive extension of arctic air over Western Canada into the Northwestern US. With multiple pieces of energy involved in such an anomalous mean trough, the Central US will likely be extremely active. Finally, the southeast ridge definitely catches your eye -- and will be extremely important in determining where any gradient does set up. Hopefully, for our snow hopes, this ridge doesn't become too anomalous or strong.

500hgtcompsup814.gif

Finally, the 5-hpa warming charts have updated and you can see a very sudden warming event has begun. The new data has us well warmer than the mean and even nearing the max/high values for the date. We have come a long way from the middle of December when we were a good bit below normal 5-hpa values. Finally, the ECMWF stratospheric warming maps show a warming event now propagating through 30 and 50 mb at Day 10. The very dramatic warming at 5mb may in this case be a red flag/warning that a more significant warming event propagating through more important levels is on the way if the ECMWF is correct. I think we are beginning to see the first real signs of a pattern change here.

As far as high latitude Atlantic blocking, I do not think we are going to be getting much help from the NAO until the stratospheric warming event occurs at 30/50 mb...etc. At that point, we may begin to see a dive into a very favorable global regime for East coast snow.

05mb9065.gif

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The tail end of the GEFS super ensemble and ECMWF ensembles offer some quickly increasing support for a very active pattern dominated by a -PNA and -EPO. Such an atmospheric regime would support a developing gradient type pattern (I know we hear this a lot, but this is almost a classic case of one) which can sometimes bring prolific snows north of the thermal gradient. It is important to notice two relatively dominant features on the super ensembles -- first a huge Pacific and Aleutian ridge which extends all the way to the Pole. Also notice the extension of the ridge over Western Greenland. Second, an increasingly large and expansive extension of arctic air over Western Canada into the Northwestern US. With multiple pieces of energy involved in such an anomalous mean trough, the Central US will likely be extremely active. Finally, the southeast ridge definitely catches your eye -- and will be extremely important in determining where any gradient does set up. Hopefully, for our snow hopes, this ridge doesn't become too anomalous or strong.

Finally, the 5-hpa warming charts have updated and you can see a very sudden warming event has begun. The new data has us well warmer than the mean and even nearing the max/high values for the date. We have come a long way from the middle of December when we were a good bit below normal 5-hpa values. Finally, the ECMWF stratospheric warming maps show a warming event now propagating through 30 and 50 mb at Day 10. The very dramatic warming at 5mb may in this case be a red flag/warning that a more significant warming event propagating through more important levels is on the way if the ECMWF is correct. I think we are beginning to see the first real signs of a pattern change here.

As far as high latitude Atlantic blocking, I do not think we are going to be getting much help from the NAO until the stratospheric warming event occurs at 30/50 mb...etc. At that point, we may begin to see a dive into a very favorable global regime for East coast snow.

as always John, a great read from you. some hope that we salvage the 2nd half of winter.

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The tail end of the GEFS super ensemble and ECMWF ensembles offer some quickly increasing support for a very active pattern dominated by a -PNA and -EPO. Such an atmospheric regime would support a developing gradient type pattern (I know we hear this a lot, but this is almost a classic case of one) which can sometimes bring prolific snows north of the thermal gradient. It is important to notice two relatively dominant features on the super ensembles -- first a huge Pacific and Aleutian ridge which extends all the way to the Pole. Also notice the extension of the ridge over Western Greenland. Second, an increasingly large and expansive extension of arctic air over Western Canada into the Northwestern US. With multiple pieces of energy involved in such an anomalous mean trough, the Central US will likely be extremely active. Finally, the southeast ridge definitely catches your eye -- and will be extremely important in determining where any gradient does set up. Hopefully, for our snow hopes, this ridge doesn't become too anomalous or strong.

Finally, the 5-hpa warming charts have updated and you can see a very sudden warming event has begun. The new data has us well warmer than the mean and even nearing the max/high values for the date. We have come a long way from the middle of December when we were a good bit below normal 5-hpa values. Finally, the ECMWF stratospheric warming maps show a warming event now propagating through 30 and 50 mb at Day 10. The very dramatic warming at 5mb may in this case be a red flag/warning that a more significant warming event propagating through more important levels is on the way if the ECMWF is correct. I think we are beginning to see the first real signs of a pattern change here.

As far as high latitude Atlantic blocking, I do not think we are going to be getting much help from the NAO until the stratospheric warming event occurs at 30/50 mb...etc. At that point, we may begin to see a dive into a very favorable global regime for East coast snow.

those dates aren't that great for our area, the gradient was def. north of the area for most of them.

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John -- great post, and agreed. As I posted in my thread, the period Jan 10-20 wlll get very active w/ the development of a -EPO and -AO, but a continued +NAO means the baroclinic zone will likely be close to our area. As you noted, hopefully for our sake, the SE ridge doesnt overpower.

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John -- great post, and agreed. As I posted in my thread, the period Jan 10-20 wlll get very active w/ the development of a -EPO and -AO, but a continued +NAO means the baroclinic zone will likely be close to our area. As you noted, hopefully for our sake, the SE ridge doesnt overpower.

Thanks bud and I fully agree.

Meanwhile the 00z GFS has my interest again for the time period I mentioned yesterday around 160 hours.

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Folks should not be ignoring the emerging weak to moderate WAA light snow risk on Friday 1/6/2011 for most of the NYC and LI including the northern suburbs area with retreating and potentially reinforced Arctic air entrenched just north of the area and WAA underway. It will likely snow in light intensities on Friday morning until mid afternoon with 1-2 inches region wide including the coastline. This threat is not to be ignored and would show up on the post 84 hour NAM if it such a run existed for the 1/3 00Z intialized run. The other risk is Wed night with some baroclinic energy, UVV in the 700 mb layers and far offshore cyclogenesi to push some -SNSH near the coast tomorrow night with a coating possible. Just my thoughts.

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Tough to tell on the black and white ggem maps, but it looks like a 998 low right off the NC coast day 6.

Ewall will show us the temp details.

On CMC color maps, if I am seeing it correctly at hour 144, 0z 1/9/12, it looks like 999 and is over Baltimore.

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