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Mid January Discussion


earthlight

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That IS an interesting comparison. I remember discussions from last year about how it was consistently cold but not severely so.

Of course, comparing # of 50+ degree highs from this dec/jan compared to dec/jan of 10/11 would paint a different picture...

Yep, that plus Dec 2011 was way warmer than Dec 2010 (mean temp of 44 vs 33) would make the difference.

Regarding 50 degree days...

In Dec 2010, we had TWO (12/1 and 12/12) and then just another two in Jan (1/1 and 1/2).

In Dec 2011, we had 16 and in Jan 2012 so far we've had 7.

So in sum, we have 4 in Dec/Jan of last winter, and 23 in Dec/Jan of this winter.

Another interesting thing is the wider spread between highs/lows this winter vs last:

From Dec 1 2010 through Jan 22 2011:

Avg high: 37

Avg low: 27

Spread: 10

From Dec 1 2011 through Jan 22 2012:

Avg high: 47

Avg low: 33

Spread: 14

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Its got a very bad antecedent airmass too, by the time it is cold enough to snow, we lost a lot of the best moisture

The storm comes in during the nightime, which helped us on the 12z ECMWF.

If I rememer correctly, the day before the October snowstorm was quite warm as well.

Dynamic and Evaporational cooling looks to take place once precipitation moves in.

It starts precipitating when it's in the upper 30s, and then cools to the mid to lower thirties in C NJ.

It cools to the middle thirties in the NYC metro region when the heaviest QPF moves in, and the lower thirties in the NW Suburbs.

That is cold enough to snow.

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The storm comes in during the nightime, which helped us on the 12z ECMWF.

If I rememer correctly, the day before the October snowstorm was quite warm as well.

Dynamic and Evaporational cooling looks to take place once precipitation moves in.

It starts precipitating when it's in the upper 30s, and then cools to the mid to lower thirties in C NJ.

It cools to the middle to low thirties when the heaviest QPF is occuring

no lie, the october setup looks colder than this one

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The NAM continues to show the potential for freezing drizzle or light freezing rain tonight throughout much of the area. You can see via the precipitation type algorithm on ewall that the NAM is picking up on the low level cold now. It looks like the potential for light freezing precipitation could exist until 04-06z.

There is a warm layer on forecast soundings at 800mb that is fairly modest in depth...but the main issue is that there is mainly low level saturation which would argue for freezing drizzle. If we can get a bit more mid level moisture, maybe we can squeeze out an hour or snow before the mid levels warm above 0 C. But I wouldn't count on that. I would think that a period of freezing drizzle or light freezing rain is more likely tonight for a few hours.

Soundings clearly show a lack of saturation above 850mb. Classic freezing drizzle sounding. But you can't rule out an isolated burst of ascent aloft that could generate a few snow crystals. That's what I'm rooting for. And there is this snippit from OKX:

MODELS CONTINUE TO SIGNAL SOME LIGHT PRECIP LATE TONIGHT INTO

EARLY MON MORNING WITH RETURN FLOW OVER SLOWLY RETREATING HIGH AND

ENOUGH ISENTROPIC LIFT/THETA E ADVECTION. IN TERMS OF PRECIP

TYPE...THE LOW-LEVEL NATURE OF THE SATURATION (BELOW SNOW GROWTH

REGION) POINT TOWARDS PRECIP IN THE FORM OF DRIZZLE. BUT

OBSERVATIONS ACROSS EASTERN VIRGINIA/DC REGION EARLY THIS MORNING

ARE SHOWING LIGHT SNOW INSTEAD OF FREEZING DRIZZLE IN A SIMILAR

THERMAL/MOISTURE PROFILE AS WHAT IS EXPECTED HERE TONIGHT. A BIT

OF A 500 MOISTURE TONGUE MAY BE ENOUGH FOR SEEDER/FEEDER

MECHANISM. BASED ON THIS HAVE ADDED SOME LIGHT SNOW TO FORECAST

FOR THIS EVENING/TONIGHT ACROSS ENTIRE REGION.

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The storm comes in during the nightime, which helped us on the 12z ECMWF.

If I rememer correctly, the day before the October snowstorm was quite warm as well.

Dynamic and Evaporational cooling looks to take place once precipitation moves in.

It starts precipitating when it's in the upper 30s, and then cools to the mid to lower thirties in C NJ.

It cools to the middle thirties in the NYC metro region when the heaviest QPF moves in, and the lower thirties in the NW Suburbs.

That is cold enough to snow.

The day before the Oct storm was in the mid 40s, pretty chilly for late October. The next day we plummeted into the low 30s.

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no lie, the october setup looks colder than this one

Yes, I agree, if you take the 12z ECMWF verbatim.

But a lot of things can change in a 7 day timeframe.

This could turn into a rainstorm and cut inland.

Or the low in the lakes could rot out earlier and we get a more favorable temperature spread across the area.

The temperature set up with the October Snow event and this one are not all that different, but the October set up probably is a bit cooler than what is being depicted on the 12z ECMWF, although not by much.

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The 12z ECMWF has highs in the upper 40s the day before precipitation moves in.

Not that much of a difference with the high temperatures beforehand, actually.

except that storm had a block and a HP over upstate ny to funnel in very low dews. This has none of that. This setup is idential pretty much to the one a few weeks back that gave Wil ORH a few inches and thats it. This has been a big problem with the euro this winter taking southern vorts and turning them into very borderline snow storms that don't verify for us.

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except that storm had a block and a HP over upstate ny to funnel in very low dews. This has none of that.

That's the main problem I'm seeing with this storm as well.

We'll see how this storm progresses over the coming days.

Yesterday's event was poised to be warmer because a high was moving out faster, and there would be no high to funnel in any cold air.

That changed with future model runs closer to the storm timeframe.

I want to see what the future model runs do with this storm, before I write anything off. Set ups can dramatically change, as we saw with the modeled predictions for yesterday's storm.

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The Euro is a big snowstorm taken verbatim...a high thickness squirrel squashing tree plastering snow.

Additionally it is the ideal outcome from that upper air set up with the secondary low bombing out to sub 998mb off the mid Atlantic coast.

exactly, the high thicknesses are disturbing, its 552+ dm at 500mb and 546+ in the 1000-500 level, thats a red flag.

And the fact that this is the IDEAL outcome means its the least likely because that is the only way we get snow in that setup and its very borderline still regardless of what the weenie maps say.

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exactly, the high thicknesses are disturbing, its 552+ dm at 500mb and 546+ in the 1000-500 level, thats a red flag.

SAT 06Z 28-JAN 4.5 -1.2 1010 82 100 0.05 555 547

SAT 12Z 28-JAN 1.6 -2.2 1003 97 98 0.49 547 545

SAT 18Z 28-JAN 2.6 -4.0 1003 83 84 0.23 543 540

SUN 00Z 29-JAN 1.9 -5.7 1008 78 28 0.00 540 533

SUN 06Z 29-JAN 0.0 -6.5 1010 78 20 0.00 535 526

That's a bit of an exaggeration.

The text printout shows that at 500 mb the majority of when it's precipitating, it is at 543-547 thicknesses in NYC.

At 1000-500 mb the thicknesses are at 540-545.

That is marginal, but it can snow at those thicknesses.

Where did you get that it's precipitating at 552+ thicknesses at 500 mb?

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Tonight's low of 18 in NYC makes it the 5th sub 20 degree low of the month and also the 5th of the season.

To compare, last winter up to 1/22/11, we had 6 such days (1 in Dec, 5 in Jan by Jan 22).

It looks like this morning's low will also be the last sub 20 low of the month... so that would be 5 so far in the winter of 11/12 vs 8 in Dec & Jan of last winter.

We haven't seen any really sustained January arctic outbreaks here since later January 2005 and especially 2004.

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SAT 06Z 28-JAN 4.5 -1.2 1010 82 100 0.05 555 547

SAT 12Z 28-JAN 1.6 -2.2 1003 97 98 0.49 547 545

SAT 18Z 28-JAN 2.6 -4.0 1003 83 84 0.23 543 540

SUN 00Z 29-JAN 1.9 -5.7 1008 78 28 0.00 540 533

SUN 06Z 29-JAN 0.0 -6.5 1010 78 20 0.00 535 526

That's a bit of an exaggeration.

The text printout shows that at 500 mb the majority of when it's precipitating, it is at 543-547 thicknesses in NYC.

At 1000-500 mb the thicknesses are at 540-545.

That is marginal, but it can snow at those thicknesses.

Where did you get that it's precipitating at 552+ thicknesses at 500 mb?

sorry meant immediately prior to the event, and they do cool, you are correct, but it just looks poor to me overall.

Its a million years away in weather time, so its gonna change. I digress.

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exactly, the high thicknesses are disturbing, its 552+ dm at 500mb and 546+ in the 1000-500 level, thats a red flag.

And the fact that this is the IDEAL outcome means its the least likely because that is the only way we get snow in that setup and its very borderline still regardless of what the weenie maps say.

To be fair though, it's not like we haven't seen high thickness snowstorms before.

Also..it's the ideal setup I would think as its modeled right now. But we won't know for sure what the synoptic set up is going to be like for several more days. We have seen the models struggling with main features of the pattern over the last two weeks. This could completely change as we approach it. Who knows. It doesn't make the storm any more likely.

At this point it's just something to keep an eye on.

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The 12z ECM is probably the best we could get out of this set up IMO... this is WAY too marginal for a snowstorm, there's plenty of room for this to cut west or just stay as a weak storm going offshore. There's barely any cold air available with no high pressure to the north of the system, and also looking back at the pattern since early December, most of the situations that had a cutoff low in the southern US followed by phasing had an inland storm track. It's not 100% impossible for us to see snow with this, especially if the set up changes to our favor which isn't out of the possibilites, considering the amount of time left, but it's definitely going to be very difficult with such a arginal set up.

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We haven't seen any really sustained January arctic outbreaks here since later January 2005 and especially 2004.

Yea, those were some COLD months.

Jan 04...

Avg High: 30

Avg Low: 18

Mean: 24

Lowest max: 15

Lowest min: 1

Jan 05...

Avg high: 37

Avg low: 25

Mean: 31

Lowest max: 18

Lowest min: 5

note: this month featured a high of 66 and a general warmer first half of the month, registering one day with a high dwpt of 60

If you take the last half of the month, 1/15-1/31 the stats are...

Avg high: 28

Avg low: 15

Mean: 22

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The 12z ECM is probably the best we could get out of this set up IMO... this is WAY too marginal for a snowstorm, there's plenty of room for this to cut west or just stay as a weak storm going offshore. There's barely any cold air available with no high pressure to the north of the system, and also looking back at the pattern since early December, most of the situations that had a cutoff low in the southern US followed by phasing had an inland storm track. It's not 100% impossible for us to see snow with this, especially if the set up changes to our favor which isn't out of the possibilites, considering the amount of time left, but it's definitely going to be very difficult with such a arginal set up.

it's hard to see but on the 500mb maps i think there is a cutoff block, albeit weak, that will likely force the storm offshore..Heck, maybe even ots like the gfs..The big worry is that right now there is not a heck of a lot of cold air showing up, and no classic high pressure. But hey, a marginal setup in the most favorable part of the year for snow..sign me up

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Yea, those were some COLD months.

Jan 04...

Avg High: 30

Avg Low: 18

Mean: 24

Lowest max: 15

Lowest min: 1

Jan 05...

Avg high: 37

Avg low: 25

Mean: 31

Lowest max: 18

Lowest min: 5

note: this month featured a high of 66 and a general warmer first half of the month, registering one day with a high dwpt of 60

If you take the last half of the month, 1/15-1/31 the stats are...

Avg high: 28

Avg low: 15

Mean: 22

Yeah, 2005 was like 2000 with all the cold coming during the second half of the month.

Those months would have looked considerably colder without all the warmth at the beginning.

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We haven't seen any really sustained January arctic outbreaks here since later January 2005 and especially 2004.

January 2009 had some fairly sustained arctic cold in the NYC metro area, although not as extreme as the outbreaks earlier in the decade. NYC finished January 2009 -4.2F, with dailies of 16/9 and 22/6 on the 16th and 17th. It was also fairly cold on the 20th and 21st of the month with highs in the upper 20s and lows in the teens.

Here is a nice picture of the partially frozen Hudson River in late January 2005, following the big arctic outbreak that occurred when I was in high school:

post-475-0-11966800-1327262373.jpg

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To be fair though, it's not like we haven't seen high thickness snowstorms before.

Also..it's the ideal setup I would think as its modeled right now. But we won't know for sure what the synoptic set up is going to be like for several more days. We have seen the models struggling with main features of the pattern over the last two weeks. This could completely change as we approach it. Who knows. It doesn't make the storm any more likely.

At this point it's just something to keep an eye on.

IIRC, the higher thickness snows usually occur when the 540 line comes north at some point during the storm as the coastal approaches the area, i can think of very few, if any, that started with unfavorable heights prior to the storm other than the usual favored higher elevations of nw jersey orange, putnam, northern fairfield up into litchfield counties.

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it's hard to see but on the 500mb maps i think there is a cutoff block, albeit weak, that will likely force the storm offshore..Heck, maybe even ots like the gfs..The big worry is that right now there is not a heck of a lot of cold air showing up, and no classic high pressure. But hey, a marginal setup in the most favorable part of the year for snow..sign me up

what do you mean cutoff block? i see now blocking on the 500mb maps of the euro.

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