January thaw may be on life support

[earthlight]

For a few weeks and even stretching back to a few months, many posters have made their opinions clear on this pattern. In regards to the La Nina pattern, the ideas of a warmer January make a whole ton of sense. In a sensible weather pattern, they do too. Make no mistake, most of the people who had this opinion are highly regarded posters or meteorologists. There was and still is a reason for this concern. Often in these patterns..the Pacific Jet can become very strong and overpower the flow into the United States leaving us with no cold air--literally a zonal flow from the Pacific. Historical data backs it up to the largest degree. But as we speak of historic, we can look elsewhere for what has been the dealbreaker thus far this winter and, by the looks of it, could continue to be: the degree of blocking.

The blocking we have been witness to over the past 12 months or so has truly been impressive. Since the middle of last winter (all of you probably remember when the pattern "flipped" in January) we have been lucky enough to have a type of block that many reference in a "textbook" winter setup. We saw it all of last February (see Feb 5, Feb 10, Feb 26, etc), we saw it even through the following months, and we've seen it so far this winter. And the last few weeks have done nothing but prove but this type of blocking anomaly can provide a very snowy situation for us--as well as below normal temperature departures.

With the system from this past weekend which gave us historical snows driving well too far to the northeast, the longwave pattern will become briefly unfavorable. But the Pacific flow will not allow for this to lock in place. A large piece of Pacific energy is already crashing into the West Coast--which will run into high heights east of the Plains and drive due north into Central Canada. This is a terrific situation for us. For one, it brings down arctic heights into Canada, again. And at the same time, it drives up the heights over Greenland...big time. The vortex that will form over Canada will be forced to become elongated by the Greenland ridging. It's almost as if we are witnessing an instant replay from what we saw in Mid December.

I think the best way to put it is to say this. Those who are forecasting mild January's (and I have seen some very, very mild forecasts)...need to send all their prayers for the ridging over Greenland to weaken completely to the point where there is a zonal flow or a trough over Greenland..or a neutral or + NAO state. These mild forecasts will not verify if the current longwave pattern remains the same..or the GEFS and to an extent ECMWF ensemble means are correct.

With that being said, there are increasing signals for a potentially stormy period on the East Coast given the current modeling strengthening the positive height anomalies over Greenland and even further to the west. This is the same west based -NAO block we saw throughout December over the same area. The GEFS ensemble mean depicts this well.. (should be noted..ECMWF ensembles are in similar agreement)..with the flat Polar Vortex and confluent flow over Eastern and Central Canada and a clear perturbation in the flow and the mean trough over the Central and Eastern United States. I think this is the period to watch for our next potential winter weather event. It should also be noted that should any semblance of a +PNA or west coast ridge build with the below depicted height pattern..the pattern would likely turn historically cold and snowy for our area..that is for sure.

[Sundog]

Nice post. It goes back to those who said that blocking has a significant impact on the Northeast winter despite their being a strong nina. We can't just say strong Nina = no snow.

[uncle W]

the January thaw usually comes the second half of the month...last year was no exception...last year was a classic January thaw between the 15th and 25th...

[NEXtreme]

Steve D is calling for a cold stormy January and he's done a great job.

[SnoSki14]

Nice post. It goes back to those who said that blocking has a significant impact on the Northeast winter despite their being a strong nina. We can't just say strong Nina = no snow.

A lot of people, myself included, have learned this the hard way. The state of the ENSO should not be used entirely to create a forecast, I know many have used it in our past hurricane season. Others said last year's strong El Nino could end up a disaster for us, now this strong Nina is not what you would expect.

Just remember 01-02, I believe it was a neutral ENSO which typically bodes well for us but it behaved like a climatological raging Nina, completely torching us.

Looks like we are seeing a semi January thaw though for the next few days, it may not be classic but it is considered a thaw if you add in the well below average month and heavy snowfall for the past month.

[WxLover]

Steve D is calling for a cold stormy January and he's done a great job.

I agree with this post.

[Chris L]

As long as the classic Greenland Block is THERE; the chances for snow and cold will come two fold. IF we bulid a classic PNA ridge, then well, we all seen this before and that COULD yield another major to blockbuster snowstorm given the amount of amplification we get within timing of the northern stream and the southern stream.

[phlwx]

the January thaw usually comes the second half of the month...last year was no exception...last year was a classic January thaw between the 15th and 25th...

This year the thaw will probably be the first two weeks.

I'm starting to see a lot of similarities to 00-01 in this winter pattern. January wasn't *that* warm here; it ended up rather average. February was mild but it also snowed well twice.

[JBG]

Nice post. It goes back to those who said that blocking has a significant impact on the Northeast winter despite their being a strong nina. We can't just say strong Nina = no snow.

I think that the analysis of La Niñas derives from a very small sample size, at least of moderate to strong Niñas.

[Alpha5]

Another great post Earthlight. Although our sample size is relatively small, I think this winter (so far) serves as a lesson between the Atlantic and Pacific patterns affect on the Northeast.

In the winter months (DJF) it seems clear now that no matter what the ENSO does, from strong nino to strong nina, as long as the NAO is strongly negative, we can get a KU storm. Of course there are more complexities than that, but I think these past two winters go to show that ultimately, the Atlantic has more sway over the pattern in the NE than the Pacific does.

[Isotherm]

Nice post. It goes back to those who said that blocking has a significant impact on the Northeast winter despite their being a strong nina. We can't just say strong Nina = no snow.

Yep, those that went with an ENSO dominated forecast look to be getting burned this winter. Usually the NAO/AO modality dictates our winter weather in the Northeast, and the winter thus far has proven that. My original outlook was near normal snowfall around 30" in NYC, but I've got to be honest, thoughts of another historic snowfall winter are rolling through my head. Either way you've got to admire the majesty of mother nature these days. 2010 was one helluva year for the books. Three major storms last February with 46" for the month here, record setting heat last summer, severe storms around the NYC area w/ tornado touchdowns, and now a very cold December, a top 3 snowstorm for my area and top 6 for NYC.

[Isotherm]

Great post John and I'm in complete agreement with it. January through mid month at least looks very interesting w/ a renewed blocking episode and more height rises in the arctic. Although the Pacific is less than desirable, we don't really need it to cooperate for light/mod overrunning events, but if we want another major storm (which to be honest, I'm now satisfied for the winter in terms of biggies, but of course I'd always take another) the Pacific needs to get more conducive w/ a PNA spike.

[Sundog]

Yep, those that went with an ENSO dominated forecast look to be getting burned this winter. Usually the NAO/AO modality dictates our winter weather in the Northeast, and the winter thus far has proven that. My original outlook was near normal snowfall around 30" in NYC, but I've got to be honest, thoughts of another historic snowfall winter are rolling through my head. Either way you've got to admire the majesty of mother nature these days. 2010 was one helluva year for the books. Three major storms last February with 46" for the month here, record setting heat last summer, severe storms around the NYC area w/ tornado touchdowns, and now a very cold December, a top 3 snowstorm for my area and top 6 for NYC.

2010 truly is one of the most extreme years I can remember. To give you an example, I've never lost power all my life due to the weather. I've lost power twice in 2010.

[Zir0b]

NYC area meteorologist PT (now known as wxoutlooks) is now forecasting a 50-60" winter for NYC metro

[MJO812]

NYC area meteorologist PT (now known as wxoutlooks) is now forecasting a 50-60" winter for NYC metro

He raised it from 25-30 inches.

http://wxoutlooks.blogspot.com/

[SnoSki14]

Wow some thaw, I'm not even going to get to 50F in the next 4 days (something that's been very common for many early January's in the 2000s), then it looks cold once again with some snowfall opportunities popping up. The block comes back strong by Day 5-6 and lasts for a while.

I'm not so sure how February and March will play out but according to Don S, we could see severe blocking in the latter half of February and into March so that will be interesting. I would enjoy a March that''s completely different from last year.

[Isotherm]

NYC area meteorologist PT (now known as wxoutlooks) is now forecasting a 50-60" winter for NYC metro

IIRC, 1955-56 produced a total snowfall of 60" out on the east end of Long Island. So basically what we could be seeing this year per him is a slightly further NW storm track w/ the NAO which would put I-95 in the heart of it. We'll see how it plays out, I'm not willing to go that extreme just yet, but right now I'd actually be shocked if we finish w/ below normal snowfall (basically would have to get virtually nothing the rest of the winter, maybe a couple minor events).

[Isotherm]

Wow some thaw, I'm not even going to get to 50F in the next 4 days (something that's been very common for many early January's in the 2000s), then it looks cold once again with some snowfall opportunities popping up. The block comes back strong by Day 5-6 and lasts for a while.

I'm not so sure how February and March will play out but according to Don S, we could see severe blocking in the latter half of February and into March so that will be interesting. I would enjoy a March that''s completely different from last year.

Yeah agreed, I remember many a nina winter (cough, 2007-08, 2008-09) torching to 60-65 degrees in advance of FROPA. Temps in the mid upper 40s is nothing, and really not that far above normal. I'm even doubtful of the upper 40s considering the deep snowpack. With the sfc low track going so far west, we may see strong CAD hold tough right up until fropa occurs.

[Zir0b]

Yeah agreed, I remember many a nina winter (cough, 2007-08, 2008-09) torching to 60-65 degrees in advance of FROPA. Temps in the mid upper 40s is nothing, and really not that far above normal. I'm even doubtful of the upper 40s considering the deep snowpack. With the sfc low track going so far west, we may see strong CAD hold tough right up until fropa occurs.

Wonder if we can sustain a long period of continuous snow cover here...after the brief warm-up we are back to highs in the 30's and lows well below freezing. Then with the next Greenland blocking episode we should add on to the existing snow-pack hopefully.

[nzucker]

Wonder if we can sustain a long period of continuous snow cover here...after the brief warm-up we are back to highs in the 30's and lows well below freezing. Then with the next Greenland blocking episode we should add on to the existing snow-pack hopefully.

Yeah I think we can have snow cover for a while...not that much will melt this weekend and then we have a sustained period of below average temperatures.

[SnoSki14]

I'm not a fan of stale snow cover. I like it for the first week or so but then it becomes hard and dirty and less than attractive. Not to mention the occasional nuisance that black ice creates. I almost slipped yesterday morning because I missed a tiny patch of black ice on the sidewalk.

I wouldn't mind it so much had the smaller roads been plowed and salted correctly, the small roads are so narrow that it's nearly impossible for two cars to bypass each other.

[jm1220]

We have to credit the southern branch as well for being much more active than is typical in strong Ninas. Perhaps it is a remnant of the old Nino from last year, but the ambush of storms into CA definitely helped us with this storm. Given the intensity of the northern branch as well, there are numerous phase opportunities. The 12z Euro today at 240 is quite impressive-it shows a closed off 500mb feature over S Texas and a temporarily favorable PNA, with a northern branch feature coming south a little too quickly to catch the southern feature. We also have to watch for clippers that can dive in and form a coastal in time to swipe us. It certainly goes to show that if this block can reassert itself we could be cashing in again next month.

[green tube]

is it realistic to think the blocking can remain a recurring feature the remainder of the winter, or do the odds drop beyond january? or are we simply in unknown territory?

[earthlight]

We have to credit the southern branch as well for being much more active than is typical in strong Ninas. Perhaps it is a remnant of the old Nino from last year, but the ambush of storms into CA definitely helped us with this storm. Given the intensity of the northern branch as well, there are numerous phase opportunities. The 12z Euro today at 240 is quite impressive-it shows a closed off 500mb feature over S Texas and a temporarily favorable PNA, with a northern branch feature coming south a little too quickly to catch the southern feature. We also have to watch for clippers that can dive in and form a coastal in time to swipe us. It certainly goes to show that if this block can reassert itself we could be cashing in again next month.

As much as it is the "southern branch"...it's not the STJ that we saw last winter. It's a function of the Pacific Jet. They are just diving south towards the Southwest US as a result of the longwave pattern. Check the 00z/30 OP GFS. At 54 hours a shortwave starts out over the Pacific. This feature comes straight from the strong Pac Jet.

http://www.meteo.psu.edu/~gadomski/AVN_0z/f54.gif

Because of the longwave pattern setup it then is forced to traverse south/southeast towards Baja.

http://www.meteo.psu.edu/~gadomski/AVN_0z/f156.gif

So in reality..it's the blocking...and the state of the PNA and the Pacific that are driving this pattern..and the southern branch activity is owing to that.

[mdsnowlover]

For a few weeks and even stretching back to a few months, many posters have made their opinions clear on this pattern. In regards to the La Nina pattern, the ideas of a warmer January make a whole ton of sense. In a sensible weather pattern, they do too. Make no mistake, most of the people who had this opinion are highly regarded posters or meteorologists. There was and still is a reason for this concern. Often in these patterns..the Pacific Jet can become very strong and overpower the flow into the United States leaving us with no cold air--literally a zonal flow from the Pacific. Historical data backs it up to the largest degree. But as we speak of historic, we can look elsewhere for what has been the dealbreaker thus far this winter and, by the looks of it, could continue to be: the degree of blocking.

The blocking we have been witness to over the past 12 months or so has truly been impressive. Since the middle of last winter (all of you probably remember when the pattern "flipped" in January) we have been lucky enough to have a type of block that many reference in a "textbook" winter setup. We saw it all of last February (see Feb 5, Feb 10, Feb 26, etc), we saw it even through the following months, and we've seen it so far this winter. And the last few weeks have done nothing but prove but this type of blocking anomaly can provide a very snowy situation for us--as well as below normal temperature departures.

With the system from this past weekend which gave us historical snows driving well too far to the northeast, the longwave pattern will become briefly unfavorable. But the Pacific flow will not allow for this to lock in place. A large piece of Pacific energy is already crashing into the West Coast--which will run into high heights east of the Plains and drive due north into Central Canada. This is a terrific situation for us. For one, it brings down arctic heights into Canada, again. And at the same time, it drives up the heights over Greenland...big time. The vortex that will form over Canada will be forced to become elongated by the Greenland ridging. It's almost as if we are witnessing an instant replay from what we saw in Mid December.

I think the best way to put it is to say this. Those who are forecasting mild January's (and I have seen some very, very mild forecasts)...need to send all their prayers for the ridging over Greenland to weaken completely to the point where there is a zonal flow or a trough over Greenland..or a neutral or + NAO state. These mild forecasts will not verify if the current longwave pattern remains the same..or the GEFS and to an extent ECMWF ensemble means are correct.

With that being said, there are increasing signals for a potentially stormy period on the East Coast given the current modeling strengthening the positive height anomalies over Greenland and even further to the west. This is the same west based -NAO block we saw throughout December over the same area. The GEFS ensemble mean depicts this well.. (should be noted..ECMWF ensembles are in similar agreement)..with the flat Polar Vortex and confluent flow over Eastern and Central Canada and a clear perturbation in the flow and the mean trough over the Central and Eastern United States. I think this is the period to watch for our next potential winter weather event. It should also be noted that should any semblance of a +PNA or west coast ridge build with the below depicted height pattern..the pattern would likely turn historically cold and snowy for our area..that is for sure.

piers corbyn from great britian , in his interiew, said basically this also, the east coast , and especially new england, was in for a snowy jan, at least , and probably the whole winter.

[Rainshadow]

Wow some thaw, I'm not even going to get to 50F in the next 4 days (something that's been very common for many early January's in the 2000s), then it looks cold once again with some snowfall opportunities popping up. The block comes back strong by Day 5-6 and lasts for a while.

I'm not so sure how February and March will play out but according to Don S, we could see severe blocking in the latter half of February and into March so that will be interesting. I would enjoy a March that''s completely different from last year.

The 500mb pattern is briefly a warm one, check out snowless DC's temps the next couple of days. If it didn't snow temps would be milder here also probably 5 to 10 degrees warmer each day. I'm surprised actually as to how warm it has become the last couple of afternoons. I have been busting on the low side. You can have a cold pattern that isn't necessarily that cold because of the winds, just like this one the snow is keeping a lid on how warm it gets.

I would agree to me January looks volatile, my WAG would be +/- 1.5F of normal. Have to give awards for the resiliency of the -nao, everything I looked at in the fall (and are dead wrong about) would have leaned toward a neutral nao for this winter. The evolution of the wpo and epo would suggest another respite second half of Jan, but given my long term track record you should read what I say and expect the opposite.

[phlwx]

The 500mb pattern is briefly a warm one, check out snowless DC's temps the next couple of days. If it didn't snow temps would be milder here also probably 5 to 10 degrees warmer each day. I'm surprised actually as to how warm it has become the last couple of afternoons. I have been busting on the low side. You can have a cold pattern that isn't necessarily that cold because of the winds, just like this one the snow is keeping a lid on how warm it gets.

I would agree to me January looks volatile, my WAG would be +/- 1.5F of normal. Have to give awards for the resiliency of the -nao, everything I looked at in the fall (and are dead wrong about) would have leaned toward a neutral nao for this winter. The evolution of the wpo and epo would suggest another respite second half of Jan, but given my long term track record you should read what I say and expect the opposite.

Outside of Saturday-Monday temps have been right around average for the past nine days in Philly. It hasn't really been too terribly cold and we'll likely end up December in the -4.5 to -5 range at PHL. Still very cold overall but the last ten days are more "typical" December than the first 20 have been.

As for the -AO that was a real surprise given how relaxed the high latitudes had gotten this year (in face the AO was neutral even positive for a couple of months). The NAO will go through 2010 negative every month...that's a first since the NAO records have been kept in '50. I bit too much into past performance = future results with the NAO winter flip (which happens about 60-65% of the time, pretty decent odds)...that doesn't look likely (at least so far) for the winter.

[Rainshadow]

Outside of Saturday-Monday temps have been right around average for the past nine days in Philly. It hasn't really been too terribly cold and we'll likely end up December in the -4.5 to -5 range at PHL. Still very cold overall but the last ten days are more "typical" December than the first 20 have been.

As for the -AO that was a real surprise given how relaxed the high latitudes had gotten this year (in face the AO was neutral even positive for a couple of months). The NAO will go through 2010 negative every month...that's a first since the NAO records have been kept in '50. I bit too much into past performance = future results with the NAO winter flip (which happens about 60-65% of the time, pretty decent odds)...that doesn't look likely (at least so far) for the winter.

Even looking at the CGD site that goes farther back with nao(s), can't find a stretch like this ever.

[famartin]

I think those of you who aren't expecting any 50s in the next few days are doing some wishful thinking... many locations hit 40 yesterday. Today will be as warm if not warmer... already most places are above freezing.

[Rainshadow]

I think those of you who aren't expecting any 50s in the next few days are doing some wishful thinking... many locations hit 40 yesterday. Today will be as warm if not warmer... already most places are above freezing.

I wonder if today and tomorrow won't have as much of a jump up because of the lack of wind. The last couple of days we had the west to northwest winds from snow free areas downsloping or advecting into the Mount Holly CWA. Anyway the bigger problem the next couple of days is not the temperatures but the dew points, they get above freezing,