NYC/PHL Dec 26-27 Potential - Part 7

[_AR_]

Don't forget to check out the chat room for BSing instead of posting it here:

http://www.americanwx.com/bb/index.php?app=ipchat

[Tiburon]

Dont shoot the messenger.. It was only mentioned as a possibility.

Not at all. Keep in mind that '93 was a 1-in-100 year storm. I'm saying that it's extremely unlikely to come any further west based on current guidance, at least relative to the PA/NJ/DE/MD area.

[earthlight]

Just an awesome image.

[A-L-E-X]

new from NCEP:

THE 12Z EUROPEAN IS VERY SIMILAR IN TRACK AND INTENSITY TO THE 00Z

RUN AND BY ITSELF COULD BE CONSIDERED A GOOD FORECAST CHOICE.

SINCE IT IS NOW RELATIVELY CLOSE TO ALL THE OTHER MODELS ANY

COMBINATION WOULD LIKELY GET A PRETTY REASONABLE FORECAST FOR THE

STORM. AS THE STORM PASSES OFF SOUTHEAST NEW ENGLAND...THE 12Z RUN

IS SLOWER THAN THE PREVIOUS VERSION AND SOMEWHAT RESEMBLES THE 12Z

UKMET STALLING THE LOW FOR A FULL DAY...IMPLYING SLOWER ENDING TIMES

FOR SNOW ACROSS EASTERN CT.

WITH THE CONVERGENCE OF ALL 12Z MODELS...MOST COMBINATION OF ANY

AND EACH WOULD PROBABLY MAKE FOR A GOOD BLEND ESP THE SNOWIER

MODELS FOR ANY GIVEN LOCATION.

If that stalls a bit further south like the GFS shows-- look out!

I like the last part most of all lol

[gkrangers]

Just an awesome image.

For us model huggers who don't know anything about weather, is that all going according to plan?

[gkrangers]

new from NCEP:

THE 12Z EUROPEAN IS VERY SIMILAR IN TRACK AND INTENSITY TO THE 00Z

RUN AND BY ITSELF COULD BE CONSIDERED A GOOD FORECAST CHOICE.

SINCE IT IS NOW RELATIVELY CLOSE TO ALL THE OTHER MODELS ANY

COMBINATION WOULD LIKELY GET A PRETTY REASONABLE FORECAST FOR THE

STORM. AS THE STORM PASSES OFF SOUTHEAST NEW ENGLAND...THE 12Z RUN

IS SLOWER THAN THE PREVIOUS VERSION AND SOMEWHAT RESEMBLES THE 12Z

UKMET STALLING THE LOW FOR A FULL DAY...IMPLYING SLOWER ENDING TIMES

FOR SNOW ACROSS EASTERN CT.

WITH THE CONVERGENCE OF ALL 12Z MODELS...MOST COMBINATION OF ANY

AND EACH WOULD PROBABLY MAKE FOR A GOOD BLEND ESP THE SNOWIER

MODELS FOR ANY GIVEN LOCATION.

If that stalls a bit further south like the GFS shows-- look out!

I like the last part most of all lol

And NCEP caves.

[Tiburon]

Just an awesome image.

Look how amplified that western ridge is. Wow.

[earthlight]

From the blog

Short Term

Apologies for the lateness of this discussion. Several changes in this forecast amidst an extremely anomalous and uncertain upper level and surface pattern. Water vapor imagery this morning shows a very strong shortwave diving southeast through the Central and Southern Plains. This shortwave was elongated through Oklahoma and back towards the Texas Panhandle. A second southern stream shortwave was located along the Gulf Coast in Lousiana. Model guidance has been fluctuating greatly with the interaction of these two features. But most notably..the model guidance was way too weak with the shortwave diving through the Plains. As of yesterdays 12z/24 model runs...only one model (GFS and GEFS) picked up on the strength of this feature. The NAM, ECMWF, GGEM, UKmet, and SREF's were all way too weak with it's vorticity and height field.

The model guidance has been playing catchup with this feature for several cycles. The result has been much more amplified solutions with the shortwave turning the height field up the east coast as the phase occurs. A strong surface low is forecast to form as the PVA increases off the Southeast Coast. Model guidance has come into decent agreement with this regard. The GFS continues to lead the way as it seems to be a model cycle ahead of every other model (noting that the SREF's have caught up to it as well).

As the two features phase, a large upper level jet phase will also occur between the two streams, and the Polar Vortex will drop southward into the upper level trough. Robust dynamics at most levels through H250-H850 are forecast to develop..including a closed H5 low south of the area which traverses to southeast of Long Island. The surface low is forecast to develop northeastward to off the Outer Banks, and then as the upper level height feild captures the surface low, it should get tugged north or maybe even briefly north/northwest. This is when the rapid development of cold conveyor belt precipitation is likely to occur.

Model guidance is indicating very strong dynamics and omega/uvv values within the favored snowgrowth region. This supports the development of very heavy snow wherever this deformation band and cold conveyor belt frontogenesis precipitation can set up. The GFS, ECMWF, and RGEM are furthest west with this feature..while the NAM and some higher resolution models are a bit further to east. It's probably not wise to try and predict this band's location...but it is worth noting that 1"/hr rates are favored within this band..so wherever it does set up could see prolific snow amounts.

Another concern with this system is the wind, with a surface low deepening into the 980's off the coast...970's on some models. Very tight isobar gradient on forecast guidance was the first sign. The ECMWF and GFS both have 75+kt low level jet signatures..and the GFS has 60+kt winds at 925mb. With a minimal inversion noted on forecast soundings it is certainly concerning that these winds are present. We opted not to issue Blizzard Advisories with the overnight package..but the later afternoon package will have to reconsider as blizzard conditions are certainty plausible with the storm track.

As far as QPF...the NAM remains furthest east but has some support from higher resolution models. We are waiting on the SPC-WRF at the moment. The GFS, ECMWF and RGEM are further west with heavy precipitation. The SREF's are also very far west with the 1" QPF line. It's probably a good idea not to bite on either side yet..but we will take a blend solution and favor the best QPF basically from NYC south and east.

For accumulations...we are currently favoring 10-18 inches on Long Island...5-10 inches with locally higher amounts near NYC and in the immediate suburbs...and 3-6 inches west of a southwest to northeast line traversing through Morristown, New Jersey. These amounts are subject to extreme change with small deviations in regards to the forecast track.

Timing...we went a bit earlier than models with snow Sunday afternoon. These systems almost always move in quicker and get out faster than forecast. The snow is forecast to be heaviest around 00z-06z Monday Morning..so please plan accordingly for traveling Monday morning. The SREF indicates 70% chance of 1"/hr snowfall rates and very low visibility. The storm should end by Monday afternoon..but we continued the watch through 5:00pm for flurries/light snow and local impacts.

Again..potentially a very high impact system with very short notice. We appreciate your patience on our product issuances. An early heads up for a potential snowstorm warning and/or associated blizzard products this afternoon /Christmas/ from us to you. Have a great holiday.

[A-L-E-X]

Not at all. Keep in mind that '93 was a 1-in-100 year storm. I'm saying that it's extremely unlikely to come any further west based on current guidance, at least relative to the PA/NJ/DE/MD area.

Jan 96 > Mar 93

As a matter of fact, Dec 92 > Mar 93

Even without snow Dec 92 caused three days of destruction here-- Mar 93 was in and out.

[JonClaw]

Look what CIPS is using as an analog for H36 on the 12z GFS

http://www.eas.slu.e...fhr=036&flg=new

1-8-96 is in that list too.

[NJHurricane]

Would this table be an acceptable snow measuring surface?

No...for some reason the table, buildings and terrain are tilted vertically, all the snow would fall off.

[hurricaneschwartz]

Hey, folks, it's Glenn at NBC10. Needless to say, I'm at work today, and we're doing regular updates on NBCPHILADELPHIA.COM, Facebook, and Twitter (if it comes back up....it's overloaded now).

[stockmanjr]

Just got an emerg alert from Luzerne County EMS.. A winter storm watch has been issued.

I normally wouldn't suggest this for snow storms but do many counties up here have Reverse 911? Might be a good idea with so many people not paying attention to TV/Radio...

Cheers!

Howie

[A-L-E-X]

No...for some reason the table, buildings and terrain are tilted vertically, all the snow would fall off.

lol it'll prob fall off anyway with the wind..... its going to be interesting trying to measure this thing-- maybe as difficult as measuring Feb 78! There might be blocks of drifts where people think they got like 3 feet, and then other blocks where people think they got shafted (or got lucky if they hate snow) where there's like 6 inches. And they wont know better until they drive around (or attempt to lol)!

[A-L-E-X]

BTW just to remind you guys-- LGA and JFK still measure snowfall from a rooftop......

[NickD2011]

Would this table be an acceptable snow measuring surface?

Is it sheltered by your house? Snow blowing off the roof and/or blocked by the house will contaminate the data.

For a storm like this the best measuring surface is a large open field or the top of a parked car in the middle of a large open parking lot

[Guest Patrick]

so we can expect snowfall reports of 0" after 1.1-1.5 of liquid equivalent has fallen? =)

BTW just to remind you guys-- LGA and JFK still measure snowfall from a rooftop......

[Tiburon]

Jan 96 > Mar 93

As a matter of fact, Dec 92 > Mar 93

Even without snow Dec 92 caused three days of destruction here-- Mar 93 was in and out.

I'm usually right with you, but I have to totally disagree. As far as meteorology and dynamics go, 3/13/93 may have been the most dynamic system of my lifetime. Barometric pressure records up and down the coast, a STORM SURGE into Florida as the squall line broke through...I respectfully disagree. '93 was a once-in-a-lifetime event, even though it wasn't the greatest for snow IMBY. That goes to '96 with a close second to the first February blizzard last year.

Look what CIPS is using as an analog for H36 on the 12z GFS

http://www.eas.slu.e...fhr=036&flg=new

1-8-96 is in that list too.

It's not a bad pattern match, but this system is modelled and progged stronger.

[bluewave]

Great discussion this afternoon from Paul Kocin.

I really miss seeing him on The Weather Channel.

http://www.hpc.ncep.noaa.gov/discussions/pmdhmd.html

[gkrangers]

Is it sheltered by your house? Snow blowing off the roof and/or blocked by the house will contaminate the data.

For a storm like this the best measuring surface is a large open field or the top of a parked car in the middle of a large open parking lot

Yeah, the wind will probably blow snow right off the roof and down into the backyard where the table is.

This is gonna be tough. Might just need to take depth measurements afterward and try to come up with some sort of ballpark accumulation average.

[hurricaneschwartz]

Hey Glenn, is the station going to put up a bug or crawl before the news casts?

We are running crawls, but are limited as to how long they are. Our website and Facebook will serve much better. We don't go on-air until 10pm on PHL17 and 11pm on NBC10.

Glenn

[A-L-E-X]

Tib, I definitely agree that overall March 1993 was much more impressive than either of those-- I just thought you were having a discussion about our local area. In terms of overall impacts nationwide and intensity, March 1993 had no equal in that century. Unless you want to compare it with the other triple phasers-- Im kind of partial to November 1950 lol, even over the OV Bomb in 1978.

The 1 in 100 year thing has been applied to a few storms though.

[Big Jims Videos]

Glenn, so many of us right now are unaware of this storm (those that don't read the message boards) I have been texting friends/family at the shore all day...posting updates on Facebook. This is serious situation especially since so many may not be paying attention to the news media during the holiday. I fear this will still catch many off guard as last night we heard reports of NYC media predicting flurries...

Our chief met even popped into to work a few minutes ago to update wnep's webpage.

[BL03]

great vid from Lee Goldberg abc7 nyc ... great simple explanation to the public on the storm around 1:30 in the vid.

also showing the mega band that will be close by.

http://abclocal.go.c...cast&id=6563415

[A-L-E-X]

so we can expect snowfall reports of 0" after 1.1-1.5 of liquid equivalent has fallen? =)

lol dont get me started-- they actually said they might have messed up with some of the measurements-- one of them, back in Feb 2008 where we had snowplows out and I measured about 4 inches and they had JFK at 0.8 Keep in mind that snowplows dont go out unless there is over 2" and JFK is only 4 miles from me

The 3/2009 storm was heavier on Long Island and NYC had 8 inches yet JFK somehow measured under 7..... most of our trained spotters in this area had like 10-11.... that was another one.

The storms last winter were hard to measure also, because of mixing and the high winds-- I noticed that the snow cover and total snowfall was taken to be the same -- which shows that it was measured at the end of the event, after who knows how much melting and/or drifting happened lol.

Someone also said that the NYC guy sometimes doesnt go to measure the snow on time because "it's too cold outside." I cant verify that but if true its just not right. That might explain the 10.0 number that they stuck with for NYC for 2/10 for the last 4 hours of the storm while it still kept snowing heavily and never updated it. EWR had like three inches more so there was a bit of an outcry over that one on here. I think there were like 3 storms in a row where NYC somehow measured snowfall to an exact inch-- that is x.0

Of course the biggest crime was the 14" recorded by JFK and LGA in 2/78 when NYC recorded 18 inches and it should have been heavier to the east. A trained spotter in Queens actually measured 22"

[Tiburon]

Tib, I definitely agree that overall March 1993 was much more impressive than either of those-- I just thought you were having a discussion about our local area. In terms of overall impacts nationwide and intensity, March 1993 had no equal in that century. Unless you want to compare it with the other triple phasers-- Im kind of partial to November 1950 lol, even over the OV Bomb in 1978.

The 1 in 100 year thing has been applied to a few storms though.

Ah, no worries, dude. I was more referring to the coastal coming closer westward into the coast (introducing dryslotting issues and possibly p-type problems). I had mentioned that if this system (specifically the H85 low) gets any closer to the coast, this is indicative that the H5 trough has sharpened SO much that it pulls the system west to an almost inland (read: disastrous) track. To get the system that far west, I'd think that it would have to wrap it up so much that it would have to resemble '93 in terms of dynamics and intensity. This thing is a monster where it is. To intensify any more would require alterning the H5 trough, and we really don't want that if we want heavy snow into our areas, though areas in the central MD-Harrisburg-State College-Poconos-Albany zone would be loving it because they would likely jackpot, and HUGE, from that scenario.

Happy Holidays, sir!

[earthlight]

MM5 total QPF

[A-L-E-X]

Ah, no worries, dude. I was more referring to the coastal coming closer westward into the coast (introducing dryslotting issues and possibly p-type problems). I had mentioned that if this system (specifically the H85 low) gets any closer to the coast, this is indicative that the H5 trough has sharpened SO much that it pulls the system west to an almost inland (read: disastrous) track. To get the system that far west, I'd think that it would have to wrap it up so much that it would have to resemble '93 in terms of dynamics and intensity. This thing is a monster where it is. To intensify any more would require alterning the H5 trough, and we really don't want that if we want heavy snow into our areas, though areas in the central MD-Harrisburg-State College-Poconos-Albany zone would be loving it because they would likely jackpot, and HUGE, from that scenario.

Happy Holidays, sir!

That storm had probably the largest conveyor belt of snow Ive ever seen.... from Alabama to Maine! Yeah, to get that kind of track in late Dec would be tragic lol-- we'd be looking at like 1-3 before a quick changeover. The arctic airmass behind March 93 was phenomenal. SST in March are about the coldest they can get also. I was lucky to get 10" in that before it changed to heavy rain on long island-- the reverse of 2/26 from last year.

Looks like Glenn has us right on the edge of 16+ !

Merry Xmas!

[A-L-E-X]

Nice post by JB

2pm update by JB

"UPDATING THIS MORNINGS POST.. SEVERE STORM TO SHUT NORTHEAST CORRIDOR PHL NORTHEAST FOR 12-24 HOURS. STORM FORCE GUSTS DELMARVA TO LONG ISLAND WITH 12-24 INCH AMOUNTS LEADING TO MASSIVE DRIFTS. AS BAD OR WORSE THAN ANY OF THE STORMS LAST YEAR FOR MANY PHL TO BOSTON, SOUTHEAST TO THE COAST. ROGUE CHARACTERISTICS WITH PRESSURE NEAR 28. 70 AT MOUTH OF DEL BAY TOMORROW NIGHT AND NEAR 28.55 BEFORE REACHING NEW ENGLAND."

[BL03]