December 19-20 Storm & Beyond: Quick Thoughts

[donsutherland1]

After last night's and this morning's model runs, the worst-case type scenario of Long Island picking up some snow while not much falls very far west of there appears increasingly likely.

The push of very cold and dry Arctic air will simply be too strong and there is good model consensus that this drier air will rapidly overwhelm cities such as Philadelphia and New York. There could be a "flash freeze" in some areas as temperatures dive, so wet pavements/roads could rapidly become icy during the nighttime hours. But that will probably be the main hazard along with increasingly severe wind chills.

Temperatures should be in the teens in Philadelphia and New York City by Monday morning with breaking clouds and perhaps just a stray flurry.

In addition, the storm's track will likely be too far to the east to bring much snowfall to most of southern New England. Eastern New England should do better.

My ideas at this point in time:

Boston: 2"-4"
Cape Cod: 3"-6" locally 8" (but much uncertainty)
Greenwich: A coating
Montauk Point: 1"-2"
New Haven: Up to 1"
New York City: No more than a coating
Newark: No more than a coating
Philadelphia: No more than a coating
Providence: 2"-4"
White Plains: No more than a coating

Moreover, in those areas marked for "no more than a coating" it is entirely possible that there is no accumulation at all.

Finally, as if this bad news were not enough, I was looking through some of Dr. D'Aleo's writings overnight. In one piece, he noted that there has never been a "Kocin snowstorm" in a month where the NAO averaged > +1.1.

Considering where December 2004 stands, unless the NAO can head negative (which I believe will happen Dec. 22 +/- 3 days) and then hold negative, from the point of climatology, the road ahead could prove quite sobering.

Fortunately, that dire outcome is not yet a certainty and the ECMWF has painted a more positive picture in terms of snowfall prospects in recent runs. For now, dreams of a post-Holiday snowstorm burn on.

Watching the NAO's progress could offer a good indication as to whether these dreams of a blockbuster snowstorm toward the end of the month will come to fruition or merely fizzle as the period in question draws closer.

Having said this, I feel like the Grinch. Lumps of coal surely await me on Christmas Day.

[rainstorm]

thanks for the info

[Skywatch_NC]

After last night's and this morning's model runs, the worst-case type scenario of Long Island picking up some snow while not much falls very far west of there appears increasingly likely.

The push of very cold and dry Arctic air will simply be too strong and there is good model consensus that this drier air will rapidly overwhelm cities such as Philadelphia and New York. There could be a "flash freeze" in some areas as temperatures dive, so wet pavements/roads could rapidly become icy during the nighttime hours. But that will probably be the main hazard along with increasingly severe wind chills.

Temperatures should be in the teens in Philadelphia and New York City by Monday morning with breaking clouds and perhaps just a stray flurry.

In addition, the storm's track will likely be too far to the east to bring much snowfall to most of southern New England. Eastern New England should do better.

My ideas at this point in time:

Boston: 2"-4"
Cape Cod: 3"-6" locally 8" (but much uncertainty)
Greenwich: A coating
Montauk Point: 1"-2"
New Haven: Up to 1"
New York City: No more than a coating
Newark: No more than a coating
Philadelphia: No more than a coating
Providence: 2"-4"
White Plains: No more than a coating

Moreover, in those areas marked for "no more than a coating" it is entirely possible that there is no accumulation at all.

Finally, as if this bad news were not enough, I was looking through some of Dr. D'Aleo's writings overnight. In one piece, he noted that there has never been a "Kocin snowstorm" in a month where the NAO averaged > +1.1.

Considering where December 2004 stands, unless the NAO can head negative (which I believe will happen Dec. 22 +/- 3 days) and then hold negative, from the point of climatology, the road ahead could prove quite sobering.

Fortunately, that dire outcome is not yet a certainty and the ECMWF has painted a more positive picture in terms of snowfall prospects in recent runs. For now, dreams of a post-Holiday snowstorm burn on.

Watching the NAO's progress could offer a good indication as to whether these dreams of a blockbuster snowstorm toward the end of the month will come to fruition or merely fizzle as the period in question draws closer.

Having said this, I feel like the Grinch. Lumps of coal surely await me on Christmas Day.

Well, Don...let's all pray and hope that you'll receive a nice orange and apple instead, Wxbuddy! You do a great job on those forecasts/analysises and S2K is quite fortunate to have you on their Met Team!!

Eric

[donsutherland1]

Thanks Eric and Rainstorm.

I'll probably post my final thoughts on this system either tonight or tomorrow morning. The 18z model runs were a little more moist in some of the locations but there don't appear to be large changes in the offing at least yet.

[ohiostorm]

What are your thoughts for the Ohio Valley?

[wxguy25]

Great Discussion.

The 12z ECMWF and 0z GGEM were really Fervent about the Xmas event in the EUS. GGEM moreso than the ECMWF but time will tell.

BOTH seem very similar and have the Arctic high in a good position for the Big cities w/ the GGEM indicating a SLP area deepening below 1000mb off the NC/VA coast.

[donsutherland1]

Great discussion, Wxguy25 on the continuing evolution of the pattern and the SSTAs.

Just so that others are clear, I'm not stating that there cannot be a Kocin-type storm just that D'Aleo's research found none when a month had an NAO average above +1.1. There are no guarantees that December will average that high. Moreover, I would be interested in checking out the storms in the new Kocin book (I'm still awaiting my copy--hopefully it will be here in time for the Holidays) to see if that still holds against a larger number of storms.

Next week certainly looks exciting both for the Ohio Valley and then later the East Coast, not to mention the Deep South, as well.

[donsutherland1]

Ohiostorm,

Ohio will see widely varying amounts. Through Sunday, most of the state should pick up some snow. However, areas prone to lake effect snow could be buried.

For some ideas:

Cleveland: 6"-10" with areas most prone to LES seeing 12" to perhaps 16"
Toledo: 1"-2"

[wxguy25]

Don, thanks for the kind words.

Your ideas on the DEC 19-20 event are looking pretty good right now per 0z ETA, as a result my call from earlier this afternoon is probably too aggressive. Ill have to tone it down tomorrow morning.

[Stephanie]

Thanks Don and wxguy for your updates as usual.

I'm not going to be too upset about this one missing us - it's just the beginning of the season. This morning though the fog was so thick, you could barely see the lampost across the street (at about 7:00)! The Canadian geese sounded like they know something's up because there was a MAJOR convention in and around my neighborhood. I could hear them honking all around me as I put my dog outside.

I'm keeping my fingers crossed for a White Christmas though for Dec 25 - 27!