NYC/PHL December 24-27 Potential Part 3

[phlwx]

I think an important thing that we are not exactly looking at here is that this is actually slower and more to the west despite the Northern Stream Lagging. In all honesty this now IMO would start to raise questions as to was the faster speed of the ECM a legit move or was it all due to lack of data of the ULL at 00z initialization?

I would imagine that the GFS means will come more west from 00z...and also interesting now to see the 12 Z ECM and see if it does slow down the Southern Stream S/W once again.

The 0z GFS was also much faster moving as well...it's squarely back on Sunday now as well.

thats a very valid point. Both the nam and gfs slowed from 0z. But wasn;t the euro slower than all of these models. They could just be finding a middle point now.

Yes -- the Euro was about 18 hours slower than the rest until last night and it's still a bit slower. There isn't any real initialization error with the models and the disturbance is now on shore in the West for the most part so the timing speed up is not surprising since there's much better data sampling.

[baroclinic_instability]

Hopefully the ensemble mean will shift west once again. BTW what's causing it to make that extreme hook?

The answer is loaded, and it would take a while to type out here. I actually wrote a little about self development in a blog post here: http://jasonahsenmac...-se-rain-event/

Give it a read if you have time. I talk about the self development process, but I don't give a reasoning for why these systems tend to "hook" NW. In this situation, air-sea interaction instability also plays a role. Either way, it should give more of an explanation as to why rapid cyclogenesis develops in the first place.

In this post, I also delve into why rapid cyclogenesis results in a farther NW track. http://jasonahsenmacher.wordpress.com/2010/11/12/centralnorthern-plains-cyclone-event-1112-142010/

Long reads, but if you have the time, it will make a lot of sense.

[A-L-E-X]

The very late negative tilt at 500....thats why I've compared it a bit to the 1989 and 3/2/09 events in that the low after initially going NE off the coast turns and goes almost due north...most major east coast events the low has a heading of 020-060 the entire time.

I remember the 3/09 comparison and its an intriguing one-- we were forecast to get 10-18 inches of snow but it was a mild bust, in reality we got 8-10 inches and parts of Suffolk County and eastern Nassau County got 12-16 inches.

[A-L-E-X]

The answer is loaded, and it would take a while to type out here. I actually wrote a little about self development in a blog post here: http://jasonahsenmac...-se-rain-event/

Give it a read if you have time. I talk about the self development process, but I don't give a reasoning for why these systems tend to "hook" NW. In this situation, air-sea interaction instability also plays a role. Either way, it should give more of an explanation as to why rapid cyclogenesis develops in the first place.

In this post, I also delve into why rapid cyclogenesis results in a farther NW track. http://jasonahsenmac...nt-1112-142010/

Long reads, but if you have the time, it will make a lot of sense.

Thanks, Im going to go and read those right now

[famartin]

I remember the 3/09 comparison and its an intriguing one-- we were forecast to get 10-18 inches of snow but it was a mild bust, in reality we got 8-10 inches and parts of Suffolk County and eastern Nassau County got 12-16 inches.

I had forecast 8-12 for my parents... they ended up with a bit over 5

[A-L-E-X]

I had forecast 8-12 for my parents... they ended up with a bit over 5

Oh no and I remember everyone was excited because that was our first coastal snowstorm since Feb 2006.

[Zelocita Weather]

Oh no and I remember everyone was excited because that was our first coastal snowstorm since Feb 2006.

Looks like we have model consensus. GFS/EURO are only 50-75 miels apart with the low placement near or slightly SE of benchmark, with anyone W of a DC to Allentown line probably out of the heavy precip chances, anyone 20 miles east of NYC probably in the heavy precip, and NYC/NJ/W CT/S NY on the fence. GFS gives N NJ/NYC 1-3/2-4 with the EURO still a 6-12 storm.

[rygar]

So, overnight basically all models now show a near miss? I haven't read the 40 pages between this thread and the 0z guidance ones.

Given la nina and how difficult it is to get this type of storm, I think it is fair to say the odds just took a big hit. We had 30-40% chance at a nyc area wide storm, and now it is around 25.

[Snow_Miser]

Looks like we have model consensus. GFS/EURO are only 50-75 miels apart with the low placement near or slightly SE of benchmark, with anyone W of a DC to Allentown line probably out of the heavy precip chances, anyone 20 miles east of NYC probably in the heavy precip, and NYC/NJ/W CT/S NY on the fence. GFS gives N NJ/NYC 1-3/2-4 with the EURO still a 6-12 storm.

I'm pretty happy with this storm right now

Euro and GFS are coming to a consensus, with the GFS trending well west overnight, and the Euro bobbling a bit east.

GFS should trend even further west, as the GEFS, usually well E of the Op. when it agrees with it, is west, and all of NJ sees 3-6" (Locally 4-8" S and E). That's a very good sign that the GFS Op. will likely shift even further west.

http://raleighwx.americanwx.com/models/gfsensemble/06zgfsensemblep72108.gif

Nice.

[SteveB]

So is it safe to say this AM that we are moving 'away' from the idea of a MECS/HECS more than we are moving closer to one?

[Snow_Miser]

So, overnight basically all models now show a near miss? I haven't read the 40 pages between this thread and the 0z guidance ones.

Given la nina and how difficult it is to get this type of storm, I think it is fair to say the odds just took a big hit. We had 30-40% chance at a nyc area wide storm, and now it is around 25.

Interesting...

Why is it down to 25%? GFS Ensembles look great.

[Snow_Miser]

So is it safe to say this AM that we are moving 'away' from the idea of a MECS/HECS more than we are moving closer to one?

Depends on where you live. The Political border between NJ and PA is the dividing line of accumulating snow, and no accumulating snow. 12Z GFS will trend west b/c 6Z Ensembles were West of the Op. mark my words.

[A-L-E-X]

Looks like GFS ensembles came in west also.

Someone should post the individual panels, I did a qpf comparison of each member at 0z and came up with a .35-.50 avg, with 2 of the members over 1 inch qpf for NYC. Looks like the new set should be even better.

[Snow_Miser]

The answer is loaded, and it would take a while to type out here. I actually wrote a little about self development in a blog post here: http://jasonahsenmac...-se-rain-event/

Give it a read if you have time. I talk about the self development process, but I don't give a reasoning for why these systems tend to "hook" NW. In this situation, air-sea interaction instability also plays a role. Either way, it should give more of an explanation as to why rapid cyclogenesis develops in the first place.

In this post, I also delve into why rapid cyclogenesis results in a farther NW track. http://jasonahsenmac...nt-1112-142010/

Long reads, but if you have the time, it will make a lot of sense.

Hi baroclinic instability,

What is your take on the Ensembles being West of the GFS Operational model?

[Snow_Miser]

Someone should post the individual panels, I did a qpf comparison of each member at 0z and came up with a .35-.50 avg, with 2 of the members over 1 inch qpf for NYC. Looks like the new set should be even better.

With High Snow Ratios, that is around 4-8."

[A-L-E-X]

Looks like we have model consensus. GFS/EURO are only 50-75 miels apart with the low placement near or slightly SE of benchmark, with anyone W of a DC to Allentown line probably out of the heavy precip chances, anyone 20 miles east of NYC probably in the heavy precip, and NYC/NJ/W CT/S NY on the fence. GFS gives N NJ/NYC 1-3/2-4 with the EURO still a 6-12 storm.

Well, I guess Im in an ok spot since Im 25 miles SE of NYC, hopefully this has room to trend maybe 50 miles further west from the GFS.

[Snow_Miser]

GFS Ensemble Mean QPF

For those that haven't seen it...

[A-L-E-X]

With High Snow Ratios, that is around 4-8."

Looks like 6z ensemble mean is even higher, more like 0.5-0.65

[rygar]

Interesting...

Why is it down to 25%? GFS Ensembles look great.

Well, I guess it depends upon where you live. In my mind included parts of NW NJ like Morris Co. in the NYC area (of course, I live there, ha) and I do think it clear that guidance is strongly suggesting any big hit will remain very close to the coastal areas.

And I am ashamed to say this, but 2 inches for christmas is a whole lot more exiting that 2 inches a day or two later. So selfish of me.

Oh, not to mention points west missed out on a lot of the action last year too. Sticks in your mind a bit.

[A-L-E-X]

ok I got the individual panel thing for the ensembles:

COD1 0.50

COD0 0.75

POD1 0.10

POD2 0.10

POD3 0.75

POD4 0.03

POD5 1.00

POD6 1.00

POD7 0.10

POD8 1.00

POD9 0.10

PO10 0.10

[A-L-E-X]

there's 3 members with over 1 inch qpf compared to 2 from the 0z ens.... and 6 members with 0.50 or more, compared to 4 from the last set of ens.

mean has also gone up from 0.35 to 0.46 FWIW

[blizzardof09]

Ok so we saw the 00z and 06z gfs trend towards the 00z euro the trends are good also ensembles being west is also a good sign. Keep in mind though the gfs is notoriously a suppreseive model it has done itg plenty of times when euro shows a nice coastal and the last minute the gfs finally catches on to the idea like 48-72 hours before the event. Everyone in the tri-state area should still be amped up about this huge storm.

[ag3]

there's 3 members with over 1 inch qpf compared to 2 from the 0z ens.... and 6 members with 0.50 or more, compared to 4 from the last set of ens.

mean has also gone up from 0.35 to 0.46 FWIW

Hey Alex. Great job with analyzing each individual.

I believe the COD1 and COD0 are the operational run and the ensemble mean.

[A-L-E-X]

Hey Alex. Great job with analyzing each individual.

I believe the COD1 and COD0 are the operational run and the ensemble mean.

Thanks Al! My numbers are slightly on the conservative side (I just took the lower end of each range), as the ensemble mean qpf map actually has us over 0.50" qpf...... the trends are looking good!

[wxologist]

Can u explain that to someone not familar. Does the 12z GFS, as depicted, most closely resemble those storms?

Yes...that is correct. Therefore if the gfs is an extreme outlier...the analogs may be poor. That being said...there could be analogs that are similar to the other deterministic output that may be worth examining that are in the top 15.

[cut]

My parents live on Cape Cod. They were supposed to get 1 to 3 on this last storm that we all lost sleep and hair over. Guess what they ended up with .... you all probably know this already ... 15 inches!!!! My dad went to bed expecting a nuisance snow the next day. My point is that in my humble opinion, it would be asking too much of these models have "zero" margin of error. I try to think of these things along the lines of a "strike cone" - albeit only the center of the cone being depicted by the models. I would dare say that if you were to look at a 72 hour forecast for a low pressure center, and then place that against the actual storm 72 hours later, you would see a "dart board" with some bulls, but more "triples".

Just some musings from a sleep deprived weather buff.

[A-L-E-X]

We wish we could get this kind of snow-- parts of Cali are buried under 17 FEET OF SNOW!

http://www.bloomberg.com/news/2010-12-22/california-records-rain-and-snow-measured-in-feet-from-storm.html

California Governor Arnold Schwarzenegger declared a state of emergency in six counties in the face of flooding rains and mounting snow from a storm that may be beneficial as well as destructive.

“The circumstances of these storms, by reason of their magnitude, are or are likely to be beyond the control of the services, personnel, equipment and facilities of any single county, or city,” Schwarzenegger said in his proclamation.

An estimated 17 feet (5.2 meters) of snow has fallen in less than a week at a monitor near the Kern River in California’s Sierra Nevada mountains, according to the U.S. Hydrometeorological Prediction Center.

Up to 17 feet of snow has fallen in the Sierra Nevada and locally over 26 inches of rain has soaked the mountains of Southern California. In addition, more than 15 inches of rain has fallen as far east as southern Utah.

....

Measuring Snow in Feet

In the Sierra Nevada mountains, snow totals are being measured in feet. The estimated 17 feet at the Pascoes near the Kern River is the highest. Other estimates are 16 feet at the West Woodchuck Meadow monitor near the Kings River and 15.9 feet at the Wet Meadow station on the Kern River, according to the hydrometeorological center in Camp Springs, Maryland.

Skiers are already benefiting. Eric Doyne, a spokesman for Ski Lake Tahoe, a marketing group for seven resorts, said this season’s opening was one of the strongest in at least a decade.

[whiteoutwx1796]

We wish we could get this kind of snow-- parts of Cali are buried under 17 FEET OF SNOW!

http://www.bloomberg...from-storm.html

California Governor Arnold Schwarzenegger declared a state of emergency in six counties in the face of flooding rains and mounting snow from a storm that may be beneficial as well as destructive.

“The circumstances of these storms, by reason of their magnitude, are or are likely to be beyond the control of the services, personnel, equipment and facilities of any single county, or city,” Schwarzenegger said in his proclamation.

An estimated 17 feet (5.2 meters) of snow has fallen in less than a week at a monitor near the Kern River in California’s Sierra Nevada mountains, according to the U.S. Hydrometeorological Prediction Center.

Up to 17 feet of snow has fallen in the Sierra Nevada and locally over 26 inches of rain has soaked the mountains of Southern California. In addition, more than 15 inches of rain has fallen as far east as southern Utah.

....

Measuring Snow in Feet

In the Sierra Nevada mountains, snow totals are being measured in feet. The estimated 17 feet at the Pascoes near the Kern River is the highest. Other estimates are 16 feet at the West Woodchuck Meadow monitor near the Kings River and 15.9 feet at the Wet Meadow station on the Kern River, according to the hydrometeorological center in Camp Springs, Maryland.

Skiers are already benefiting. Eric Doyne, a spokesman for Ski Lake Tahoe, a marketing group for seven resorts, said this season’s opening was one of the strongest in at least a decade.

I'm going there xmas day....More Rains and +SN's Saturday night., then more new years eve.

[A-L-E-X]

Do you ski? Thats probably one of the best places in the country to ski lol.

[Parsley]

Looks like I-95 could be the dividing line between a few inches to the west, and plowable snows to the east. I'd be very excited if I was on Long Island or in New England at this time.