NYC/PHL Potential Jan 11-14 Event Discussion

[ag3]

Looking at Euro Spaghetti charts,

At hour 114, the overwhelming majority of members are NW of Operational and a bunch of them are stronger. At hour 126, Most ensemble members are West of Operational and lot of them also stronger.

[_AR_]

I have a bad feeling about having the UKMET and NOGAPS so far west at this range.

[jm1220]

JM, do we usually change over if Philly does? My experience with winters like 93-94 tells me otherwise... usually the changeover line takes 4 hours to get here from ACY (on average.)

If it's from a low tracking up the coast, we very often change over after they do and when there's a low over Cape May like last night's GGEM showed, it's very rarely good for us. Even if we don't change over, the dryslot is right at our doorstep and the low would have to scoot east in a hurry to keep us in heavy precip.

However, if there's a miller B or redeveloper type situation with one center west of the Apps and one on the coast, PHL can change over and we stay snow. It's happened a few times such as 12/5/03 when downtown PHL went to rain for a time but we snowed away all day. I think 12/20/95 was another such instance. 12/14/07 was close to being a lot snowier here as well, and that was a SW Flow event.

It all depends on the degree of phasing and the amplification of the system and downstream ridge. I'd still say odds are against us changing over but it's still a possibility. More so I think than it completely missing out to sea. This could finally be a storm that delivers a sizeable snow event to much of PA and the interior Mid Atlantic that's missed out on our fun over the last month.

[earthlight]

Overwhelming majority of Euro members are north and west of the OP..there are some very big hits. A whole bunch of them.

[stormman]

Overwhelming majority of Euro members are north and west of the OP..there are some very big hits. A whole bunch of them.

yea looks awesome, but for some reason DT keeps saying that models like the gfs and canadian are continuing to trend east, and says the pattern doesnt really support a big storm riding up into the big cities?

[Manny]

Overwhelming majority of Euro members are north and west of the OP..there are some very big hits. A whole bunch of them.

I know last night this was mentioned, but do you have concerns about P-type issues for the coast, even with low track so close to the coast like the GEM showed, or is the cold air available regardless of the closeness of the track?

[tombo82685]

ahhh sorry i missed the euro guys, i was up for 22 hours straight and just finally passed out around 1130. Euro is a decent hit with the ull for nyc to phl and coastal .5-.75

[Zir0b]

18z NAM at 84 looks considerably more amplified than the 12z GFS at 90.

[Alpha5]

The Euro ensemble mean is clearly west of the operational. Variance is getting smaller. It's not a fan of the Miller B scenarios, but from what I can tell on the spag charts, there are quite a few members that go up the Appalachians or Susquehanna Valley. Not nearly as many OTS members this time around either. I'd call this a big win for us.

Yup, the Euro spag plots reveal that the OP is indeed a southeast outliner, GGEM/GFS ensembles concur with the Euro ens

[SACRUS]

ahhh sorry i messed the euro guys, i was up for 22 hours straight and just finally passed out around 1130. Euro is a decent hit with the ull for nyc to phl and coastal .5-.75

Thats no excuse Tom.

Just kidding. Thanks for your udpates.

[MJO812]

12z Euro ensemble mean. Looks like a BM hit.

[Zir0b]

I find it very strange that the ensembles of 3 major models are considerably further west/more amplified with the possible storm. Anyone know why this could be the case?

[SACRUS]

I have a bad feeling about having the UKMET and NOGAPS so far west at this range.

I know what you mean, but I personally would rather the consensus than them being out to sea. The ensembles gfs and ecm support the ggem and ukmet. 18z op gfs probably wont be far behind.

[Alpha5]

I find it very strange that the ensembles of 3 major models are considerably further west/more amplified with the possible storm. Anyone know why this could be the case?

Good point, I dont have an answer but the GGEM/GFS/Euro OP's are all more progressive and further se than their means

[NaoPos]

ahhh sorry i missed the euro guys, i was up for 22 hours straight and just finally passed out around 1130. Euro is a decent hit with the ull for nyc to phl and coastal .5-.75

Don't ever leave me in this thread again doing the PBP.. i was like raw meat in a hungry lions den

[NaoPos]

Good point, I dont have an answer but the GGEM/GFS/Euro OP's are all more progressive and further se than their means

even the nogaps ensembles were more NW than the ops..

[tombo82685]

Don't ever leave me in this thread again doing the PBP.. i was like raw meat in a hungry lions den

hahahha...yea despite the coastal miss it still gets us good with the ull and inverted trof like feature.

[A-L-E-X]

hahahha...yea despite the coastal miss it still gets us good with the ull and inverted trof like feature.

Not only did you miss the euro, you missed most of the "storm"-- haha it wasnt such a big deal here.

[tombo82685]

Not only did you miss the euro, you missed most of the "storm"-- haha it wasnt such a big deal here.

hahahaha, yea i can see it was lol

[Tiburon]

If it's from a low tracking up the coast, we very often change over after they do and when there's a low over Cape May like last night's GGEM showed, it's very rarely good for us. Even if we don't change over, the dryslot is right at our doorstep and the low would have to scoot east in a hurry to keep us in heavy precip.

However, if there's a miller B or redeveloper type situation with one center west of the Apps and one on the coast, PHL can change over and we stay snow. It's happened a few times such as 12/5/03 when downtown PHL went to rain for a time but we snowed away all day. I think 12/20/95 was another such instance. 12/14/07 was close to being a lot snowier here as well, and that was a SW Flow event.

It all depends on the degree of phasing and the amplification of the system and downstream ridge. I'd still say odds are against us changing over but it's still a possibility. More so I think than it completely missing out to sea. This could finally be a storm that delivers a sizeable snow event to much of PA and the interior Mid Atlantic that's missed out on our fun over the last month.

I know you guys already know this, but a good indicator of how the changeovee line evolves is the placement of the primary H85 low. If your surface reflection is over Cape May, you can bet that the H85 low is to the west or southwest, and if the H85 low tracks to your west, you're changing over almost without question.

Dryslotting is something that I look at the H7 level to try and predict. Even still, the dryslot is very hard to pin down, and is better nowcasted through water vapor.

In the case you mentioned above--a Miller B--for PHL to remain all snow, that center cutting up the Apps has to transfer muy quickly, or you get the southerly/south-southwesterly flow, warmer air, and an inevitable changeover, or delay in frozen precip. If you get the completed transfer by the time the coastal is around Wallops Island, PHL is usually pretty good. For you guys up by NYC, regardless of what Miller category cyclogenesis you're seeing, because you're relatively further east than PHL, you need to hope for the more ENE/and even better NE motion of the low to keep the H85 low to your east and to keep the flow out of the N and NE.

An ideal track for PHL and NYC is one with a coastal 75 miles off ACY moving NNE--that runs the risk of screwing Boston and the Cape. To get everybody in on the happy action, you almost need that track to get from 75 miles off ACY to continue toward the benchmark and follow the coast's orientation--more NNE then NE then ENE.

[jm1220]

I know you guys already know this, but a good indicator of how the changeovee line evolves is the placement of the primary H85 low. If your surface reflection is over Cape May, you can bet that the H85 low is to the west or southwest, and if the H85 low tracks to your west, you're changing over almost without question.

Dryslotting is something that I look at the H7 level to try and predict. Even still, the dryslot is very hard to pin down, and is better nowcasted through water vapor.

In the case you mentioned above--a Miller B--for PHL to remain all snow, that center cutting up the Apps has to transfer muy quickly, or you get the southerly/south-southwesterly flow, warmer air, and an inevitable changeover, or delay in frozen precip. If you get the completed transfer by the time the coastal is around Wallops Island, PHL is usually pretty good. For you guys up by NYC, regardless of what Miller category cyclogenesis you're seeing, because you're relatively further east than PHL, you need to hope for the more ENE/and even better NE motion of the low to keep the H85 low to your east and to keep the flow out of the N and NE.

An ideal track for PHL and NYC is one with a coastal 75 miles off ACY moving NNE--that runs the risk of screwing Boston and the Cape. To get everybody in on the happy action, you almost need that track to get from 75 miles off ACY to continue toward the benchmark and follow the coast's orientation--more NNE then NE then ENE.

Good post. With redevelopers, you have more wiggle room the further north you are with the R/S line. When the coastal takes over, unless its on the shore, the WAA stops and the snow line stays put and eventually goes south. A good case in point is the 2/14/07 event. The primary over the Ohio Valley was very strong, and produced over 12" of snow for much of IN/OH, but it was slow to weaken and the 850/700 mb lows stayed intact and produced much more WAA than advertised well into PA and even upstate NY. I remember sleet taking over early that evening when it wasn't even supposed to maybe mix in until late that night. It kept sleeting until the coastal finally took over, and switched me back over to all snow, and luckily there was a deformation band that stretched down through central NY and PA, otherwise we would've had 7-8" tops when we were forecasted to get up to 18". We ended up with about 11" of cementlike thick snow and sleet that froze into a solid brick. But once you got to around Binghamton, there was no mix and that's where the 18"+ amounts began.

This is an old picture I have from downtown State College on the afternoon of 2/15/07:

When the 850 and 700 lows track west of you, that's when you know you're in for the dryslot and changeover.

[ag3]

DGEX at hour 108..Close to coast:

[gkrangers]

Any fears of this cutting ?

[A-L-E-X]

I know you guys already know this, but a good indicator of how the changeovee line evolves is the placement of the primary H85 low. If your surface reflection is over Cape May, you can bet that the H85 low is to the west or southwest, and if the H85 low tracks to your west, you're changing over almost without question.

Dryslotting is something that I look at the H7 level to try and predict. Even still, the dryslot is very hard to pin down, and is better nowcasted through water vapor.

In the case you mentioned above--a Miller B--for PHL to remain all snow, that center cutting up the Apps has to transfer muy quickly, or you get the southerly/south-southwesterly flow, warmer air, and an inevitable changeover, or delay in frozen precip. If you get the completed transfer by the time the coastal is around Wallops Island, PHL is usually pretty good. For you guys up by NYC, regardless of what Miller category cyclogenesis you're seeing, because you're relatively further east than PHL, you need to hope for the more ENE/and even better NE motion of the low to keep the H85 low to your east and to keep the flow out of the N and NE.

An ideal track for PHL and NYC is one with a coastal 75 miles off ACY moving NNE--that runs the risk of screwing Boston and the Cape. To get everybody in on the happy action, you almost need that track to get from 75 miles off ACY to continue toward the benchmark and follow the coast's orientation--more NNE then NE then ENE.

I like to use specific storms to illustrate what I think of ideal tracks, and the tracks that come to mind that were great for us all (well most of us lol).... are the types of tracks that Feb 83, Jan 96 and PD2 took as far as Miller As are concerned.

Now as far as Miller Bs are concerned, it gets a bit more complicated, as we dont have a one size fits all scenario, but some of our best Miller Bs happened back in the 60s like Feb 69 and storms like Feb 78 and Jan 05.

[Tiburon]

Good post. With redevelopers, you have more wiggle room the further north you are with the R/S line. When the coastal takes over, unless its on the shore, the WAA stops and the snow line stays put and eventually goes south. A good case in point is the 2/14/07 event. The primary over the Ohio Valley was very strong, and produced over 12" of snow for much of IN/OH, but it was slow to weaken and the 850/700 mb lows stayed intact and produced much more WAA than advertised well into PA and even upstate NY. I remember sleet taking over early that evening when it wasn't even supposed to maybe mix in until late that night. It kept sleeting until the coastal finally took over, and switched me back over to all snow, and luckily there was a deformation band that stretched down through central NY and PA, otherwise we would've had 7-8" tops when we were forecasted to get up to 18". We ended up with about 11" of cementlike thick snow and sleet that froze into a solid brick. But once you got to around Binghamton, there was no mix and that's where the 18"+ amounts began.

This is an old picture I have from downtown State College on the afternoon of 2/15/07:

When the 850 and 700 lows track west of you, that's when you know you're in for the dryslot and changeover.

I remember virtual tracking that storm with Steve DiMartino (nynjpaweather) on Eastern, just waiting for the running primary to die out, and having my heart broken. That's what happens when a vertically stacked low doesn't behave how you want it to.

DGEX at hour 108..Close to coast:

Verbatim, that's BIG trouble for TTN south, and Lancaster, PA, BWI/DCA straight on east. That's rain or slop, and that's exactly what we were talking about above. That's the dominant feature not transferring in time. Yuk.

[Chris L]

The best Miller B for the Mid Atlantic States has got to be February 9-10th 2010, when the H500 low went so far south and then you know the rest;.... And the H700 and H850 lows has to go southeast of PHL to stay all snow to prevent the risk of change over and dryslot.

I really would love to see another February 9-10th style Miller B.

[A-L-E-X]

A notorious Miller B bust (SG knows about this one) was back in Dec 89, the notorious cold month with little snow-- we had a storm track that was supposed to give us 6-8 inches of snow but the primary held on too long and the seconday developed too close to the coast, and the snow quickly changed to rain and we even had thunderstorms (with rain not snow) because the coastal developed almost right over us. That month also featured the notorious virga storm; another prediction of 6-8 that went bust because all the snow fell in the atmosphere and none of it reached the ground-- DC was hit hard, I believe. And the previous winter, what would have been PD2 (Feb 89) and should have given us a foot of snow, gave ACY 19 inches instead and nothing to us. Needless to say, outside of a rogue storm in Nov 89, that was a pretty bad year for us and the three years that followed werent any good either (outside of the 1991 summer, if you like scorching summers lol.)

[A-L-E-X]

VD 07 wasnt bad around here-- at least it stayed all frozen lol-- the 32F line stayed east of us (I believe suffolk county went over 32).... ditto with March 07.

[Isotherm]

I just made a post on next week's event, I think a Lakes-cutter/inland runner is highly unlikely with the blocking regime across Canada. However, if the primary makes it to the OH valley, the NE confluence/ridge axis will ensure a transfer to a coastal secondary. IMO this could be a widespread SECS type event from the TN valley into the mid and north atlantic, SNE.

http://www.lightinthestorm.com/archives/321

[Grothar]

Any fears of this cutting ?

I hope it does