NYC/PHL Dec 26-27 Potential - Part 7

[BL03]

Here's my call on this event...

Steep gradient just to the NW of a mega deformation band which is likely to develop from SNJ northeastward through CNJ, NYC and western/central LI. I expect slightly less totals on the east end of LI due to dry slot potential from H7 low directly over that area. Basically a moderate event from the DE River westward. Major event of 12"+ from about I-95 eastward. That 12-18"+ band is the hardest to figure out - could be a little west of where I have it, that's my worry.

I think E PA get 6-12" ...uplift, higher ratios.

[am19psu]

Isotherm, I would put the heavy band farther inland, but I can't really fault your map. Good job!

[BL03]

Is it possible we'll see this again?

I THINK SO....

[gkrangers]

Here's my call on this event...

Steep gradient just to the NW of a mega deformation band which is likely to develop from SNJ northeastward through CNJ, NYC and western/central LI. I expect slightly less totals on the east end of LI due to dry slot potential from H7 low directly over that area. Basically a moderate event from the DE River westward. Major event of 12"+ from about I-95 eastward. That 12-18"+ band is the hardest to figure out - could be a little west of where I have it, that's my worry.

Please verify.

[NJwinter23]

When does my blizzard warning go up damnit lol...I wanna see that red outline on my county, what's the hold up Mount Holly?

Starting to get very concerned about the damaging wind potential some models are showing in the coastal areas. Would anybody else care to comment?

[gkrangers]

When does my blizzard warning go up damnit lol...I wanna see that red outline on my county, what's thw hoild up Mount Holly?

Same. Not sure they'll do it. Not that it matters. 12"+ and some good wind with a WSW is enough for me!

[mattinpa]

I think E PA get 6-12" ...uplift, higher ratios.

That would be my call, too. Ratios would be around 15:1, right?

[jm1220]

i wouldn't rule out a track like the RSM, very close to the coast/ hugging the coast maybe 30 miles off. The h5 low is gonna deepen hardcore tomorrow afternoon and really no one can predict how it will move north of Delaware imo. I really hope it doesn't get too close to the coast because that will bring the dryslot/ eye closer to the coast and the mega band more NW!

There's almost ALWAYS a mega band that sets up in north central NJ and into southern NY, because of the hilly terrain there and the forcing associated with the storm, which adds to the lift over those areas, as well as the colder air there and resultant higher ratios. The exceptions are storms like last 12/19 which was centered around here and east, so they avoided a lot of the main effects of the storm. This one looks to be a bit further west, so they will likely have a jackpot somewhere in the West Milford/Morristown areas.

[_AR_]

Blizzard warnings may not be needed until the event starts for Mt Holly counties. They may wait to see how the winds look then.

[ace0927]

I THINK SO....

that storm will be a domestic cat compared to this beast

[eduggs]

what the heck is this- what is central pressure down to???? Also, how is there relatively NO PRECIP falling anywhere with a sub 970 MB low???

Pressure gradient or deep pressures don't generate precipitation. You need vertical lift... which is associated with DEEPENING low pressure and/or temperature advection. The low is occluded and vertically stacked when it reaches 970 central pressure, hence the associated precip has or is weakening.

[BL03]

I really feel the 21 SREF mean slp track is gonna verify ..maybe very slightly nw but not much. And it continues to hammer the idea of a mega band... .5"+ from 21z-03z .

[dryslotted]

I THINK SO....

I do too and who would have thought we'd see something like it again in less than a year...

[BL03]

That would be my call, too. Ratios would be around 15:1, right?

for E PA ..yes imo.

[eduggs]

It's vertically stacked and occluding, meaning the major lifting stops near the low. The 2/25/10 storm did the same thing over us. Even though we had a low 970s low right near us, the snow stopped on the 26th because the low became stacked.

Ah, I see you already had this covered. Nice.

[ace0927]

Pressure gradient or deep pressures don't generate precipitation. You need vertical lift... which is associated with DEEPENING low pressure and/or temperature advection. The low is occluded and vertically stacked when it reaches 970 central pressure, hence the associated precip has or is weakening.

aaaah, thank you.

[am19psu]

I really feel the 21 SREF mean slp track is gonna verify ..maybe very slightly nw but not much. And it continues to hammer the idea of a mega band... .5"+ from 21z-03z .

Why?

[chubbs]

I would second the 6-12 for E Pa. Difficult forecast with conflicting guidance.

[Isotherm]

Looks like it was derived from a good blend of the models. Good map...

Agreed.

Isotherm, I would put the heavy band farther inland, but I can't really fault your map. Good job!

Please verify.

Thanks! I hope it verifies. And yeah my main concern w/ the deformation band is its a bit further west than I have it. But either way,

[eduggs]

Despite what stormguy says, I wouldn't trust anything it says. I don't know why people post it here.

Pretty good track record for the model. Canadians say it's a great short range model - better than GFS or NAM. Anecdotally, when I've payed attention it has done well with SLP track and QPF distribution with coastal snowstorms. It definitely concerns me a little bit.

[Ridingtime]

I do too and who would have thought we'd see something like it again in less than a year...

That's actually the record breaking Feb 2006 storm. So not quite less than a year but with all things considered it's relatively not far off.

[LocoAko]

Just for fun...

For Newark, NJ from the 15Z SREFs,

~4 members give <5.0"

~6 members give 12.0-18.0"

~6 members give 24.0"-30.0"

1 gives near 40.0"

Mean: 18.1"

[Isotherm]

Same. Not sure they'll do it. Not that it matters. 12"+ and some good wind with a WSW is enough for me!

Yeah, I don't know the wind field looks about as impressive as it can get with a winter storm. I'd be surprised if we're not in one by tomorrow morning.

[NJwinter23]

Well the 00z nam because its a little further east isnt quite as bullish with the LLJ over NJ so were only gusting 35-40kts during the hieght of the storm Sunday night . That still warrants blizzard warnings id say

[NorthNJwx]

When does my blizzard warning go up damnit lol...I wanna see that red outline on my county, what's the hold up Mount Holly?

Starting to get very concerned about the damaging wind potential some models are showing in the coastal areas. Would anybody else care to comment?

I'd definitely like to comment...the threat here is real. Note: I'm referring to the GFS and other west models here...not the NAM necessarily (that said, the 0z NAM still looks to crank the LLJ to 50kt + after the heaviest snow ends).

The strength of the winds aloft and the incredibly tight surface gradient just scream potential. I think the fact that the wind direction is progged to be N-NNW (as opposed to an easterly component direction) may be important. Any type of onshore flow is typically limited by a significant inversion, but a N-NNW wind is usually a different story...mixing tends to be better. I'm not seeing a strong inversion here that would keep winds aloft from potentially mixing down.

For inland areas, I think the threat is also there as well, since an offshore flow tends to be MUCH more conducive to mixing and gusts there. At my location, that's certainly the case.

It seems that peak gusts of 60-65 could be realized near the coast and closer to the 45-55 range/maybe localized to 60 inland. I checked a forecast for a coastal NJ location, and Mt. Holly is indeed calling for gusts to 60 there.

[gkrangers]

GFS is running.

[IsentropicLift]

The NAM still gives me a very nice hit but just to make things comfortable I'd definitly like to see the GFS and Euro at least hold serve at 00z. With the roller coaster ride we have been on this week nothing is a definite until we can see it on radar.

[Zir0b]

Just for fun...

For Newark, NJ from the 15Z SREFs,

~4 members give <5.0"

~6 members give 12.0-18.0"

~6 members give 24.0"-30.0"

1 gives near 40.0"

Mean: 18.1"

I know you wrote the 15z SREFs, but are you actually talking about the 21z?

[Allsnow]

Yeah, I don't know the wind field looks about as impressive as it can get with a winter storm. I'd be surprised if we're not in one by tomorrow morning.

What has me concern about wind potential...and im talking imby in holmdel/edison those 3 storms in febuary the wind field look impressive and it never verfiyed.....2-10 was a lock for heavy winds it seem....we had a blizzard warnning issued...and it seemed nothing ever happened

[jdt]

I think E PA get 6-12" ...uplift, higher ratios.

Its all about the meso banding. If you are either side of it you may suffer from sinking area thus lighter precip regardless of any terrian uplift enhancements. Now if the banding sets in an area with the right orientation to a terrain feature then that area may see some additional enhancement above and beyound what the banding would normally bring. Again it will all come down to where this banding sets up and the moves. His map is basically is call to say the banding will be along and near the coast. That is a very reasonable call but could it be a little further west? Sure but nobody can answer that question with absolute certainty at this point.