NYC/PHL Jan 25-27 Potential Bomb Part 5

[TheTrials]

back to the ukmet for a moment, ewall images shwo a very nice storm for the ny metro.

[isnice]

For Somerset County should I be looking at EWR/NYC totals, and maybe a little more frozen because we're West...but not "inland" enough for all snow?

Being in my area kinda sucks on here because its in between everything

I use ksmq...somerville

[A-L-E-X]

The 12Z runs would indicate this has 12/03 type potential as far as what happened on the first day of the event...everyone thought it would be a rain-snow transition...looking at this event I see no reason why it may not surprise people again by being mostly snow now....I think the models may be a bit generous with the mid-level warming and its close anyway....the surface doesn't look to be an issue, the GFS MOS shows 37/29 over JFK at 18Z but thats with a 030 wind.

lol it sounds like your thinking on this event has changed.

[yankeex777]

WOW. The euro basically shoves the PV into the Northeast. Frigid temps late in the run.

Is that feb2-3 storm still there?

[A-L-E-X]

WE need to build the -NAO like we had a few week ago...

WOW. The euro basically shoves the PV into the Northeast. Frigid temps late in the run.

That's our deeply negative AO/NAO showing up during the first week of February. Just the beginning of what might be a really nice run.

[Inudaw]

Is that feb2-3 storm still there?

Does not look like it... looks like a strong arctic front just pushes through between the 1st and the 2nd... can't really tell based on E-Wall though... does not appear to be a huge storm anywhere..

[famartin]

To an extent the high is still pulling a screw job at 54 hours....without the high to the east the flow around the east side of the storm would not be so violently strong out of the SE and less warm air would likely be pulled in at the mid-levels....I probably shouldn't have phrased it as WAA but stated more that SW to NE flow events is usually where the models underdo the warmth and much less so in a case like this where its more a typical warm air wrapping around the east side of the system.

1993, 1996 and 2000 all featured an unexpected extent of warming. In 1993 it changed over to sleet all the way to NW Jersey and ABE (I don't think that was forecast). 1996 it mixed with sleet briefly all the way up to NYC (and totally ripped off much of S Jersey and DC). In 2000 the warm air screamed in from the east and most of Jersey and NYC changed to sleet/frz rain most of the day. There are few Miller-A scenarios which show this kind of warm air in place before the storm even starts so its hard to give many examples in recent years. But that's the key: that the warm air is essentially already in place before the storm even arrives. If the models start showing sub freezing temps as the storm is moving in, then I can see it being mostly snow.

[Ed Lizard]

I doubt the surface or boundary layer is a problem for Long Island in this event, my guess is the trouble could come if some stubborn layer stays .5 or .7 above freezing at 870mb and causes tons of sleet....I just don't buy issues in the BL given it likely will be clouded over early in the morning, the wind flow is NE and there may be an ample period of radiational cooling early the night before.....this is an event where LGA could snow for 8 hours and JFK for 4 due to sleet issues.

12Z Euro graphics not up on AccuWeather, I can get a forecast skew-T at a 6 hour interval for any particular lat/long when it does update, but for now, with just text output, and 2 meter and 850 mb temps, hard to be super accurate. But KFRG 850 mb temps are 2ºC at the height of the precip (prior six hours, 0.44" QPF, following 6 hours, 0.36") with a forecast 2.4ºC 2 meter temps, which is why I think mostly a very cold rain on the Island.

[blazess556]

There is no big storm on the euro but there is a ton of potential with a +PNA and the -AO/-NAO combo reappearing. Fun times look to continue into the near future.

[Manny]

This upcoming storm just shows how active this year has been, and the different scenarios involved throughout the year. This storm reminds me of last year with marginal temps and the ability for it to still be a nice event for many.

[tcutter]

1993, 1996 and 2000 all featured an unexpected extent of warming. In 1993 it changed over to sleet all the way to NW Jersey and ABE (I don't think that was forecast). 1996 it mixed with sleet briefly all the way up to NYC (and totally ripped off much of S Jersey and DC). In 2000 the warm air screamed in from the east and most of Jersey and NYC changed to sleet/frz rain most of the day. There are few Miller-A scenarios which show this kind of warm air in place before the storm even starts so its hard to give many examples in recent years. But that's the key: that the warm air is essentially already in place before the storm even arrives. If the models start showing sub freezing temps as the storm is moving in, then I can see it being mostly snow.

at least that gives us something to look and hope for!!

[NJwinter23]

lol it sounds like your thinking on this event has changed.

Were just trying to interpret the model runs and the setup. It has evolved greatly over the past few days Alex. When I was saying rain a few days ago, it was because the storm was amping up the coast on the models with the high moving offshore and torching east winds. And even now though with the ideal track depicted on the gfs/euro, we're still battling some warm air issues with the cold high long gone. So you can see why I was skeptical on a meaningful mostly snow event for us as even the ideal scenario/storm track may not be all snow at least as the models are saying.

[A-L-E-X]

1993, 1996 and 2000 all featured an unexpected extent of warming. In 1993 it changed over to sleet all the way to NW Jersey and ABE (I don't think that was forecast). 1996 it mixed with sleet briefly all the way up to NYC (and totally ripped off much of S Jersey and DC). In 2000 the warm air screamed in from the east and most of Jersey and NYC changed to sleet/frz rain most of the day. There are few Miller-A scenarios which show this kind of warm air in place before the storm even starts so its hard to give many examples in recent years. But that's the key: that the warm air is essentially already in place before the storm even arrives. If the models start showing sub freezing temps as the storm is moving in, then I can see it being mostly snow.

I agree and think a rain to snow scenario is more likely. Besides Xmas 2002 and Dec 2003, we had a few of those back in the 90s... notably Nov 95, Mar 96...and a couple in 93-94 also.

[mulen]

I guess the trend is your friend SNE should get pleasantly surprised and someone gets nailed good .This winter will have its own unique analog to be used by climatologists in the future because hardly anyone predicted up till now what has happened in the N.E see ya.

[famartin]

Alright... I'm not a big fan of making a call like this with the system so far out... but here's my thinking for TTN:

Starts as some sleety mess, goes to rain, then over to snow. 3-6 inches. I'm not looking at NYC, don't even try to make me

[A-L-E-X]

Were just trying to interpret the model runs and the setup. It has evolved greatly over the past few days Alex. When I was saying rain a few days ago, it was because the storm was amping up the coast on the models with the high offshore and torching east winds. Even now though with the ideal track depicted on the gfs/euro, we're still battling some warm air issues and what that could mean for the coastal plain. So you can see why I was skeptical on a meaningful mostly snow event for us as even this ideal storm track may not be all snow at least as the models are saying.

I agree and I still think our "best case" scenario is probably 50/50 rain/snow but even that is being highly optimistic. Based on how we've typically done in backside snow situations, I would say 67/33 rain/snow is a safer bet. So if we had 1.5 QPF, 0.5 as snow would be the best we should expect, and probably 8:1 ratios.

[A-L-E-X]

Alright... I'm not a big fan of making a call like this with the system so far out... but here's my thinking for TTN:

Starts as some sleety mess, goes to rain, then over to snow. 3-6 inches. I'm not looking at NYC, don't even try to make me

lol you cut off all the IMBY questions at the pass

[NJwinter23]

Alright... I'm not a big fan of making a call like this with the system so far out... but here's my thinking for TTN:

Starts as some sleety mess, goes to rain, then over to snow. 3-6 inches. I'm not looking at NYC, don't even try to make me

Very reasonable Ray and this is my thinking as well. GFS bufkit supports you as well

[WintersGrasp]

Alright... I'm not a big fan of making a call like this with the system so far out... but here's my thinking for TTN:

Starts as some sleety mess, goes to rain, then over to snow. 3-6 inches. I'm not looking at NYC, don't even try to make me

That definitely sounds legit....this thing really tightens up as it pulls away and turns to snow. I think even Monmouth county in NJ could easily see 6"+. arreas not too far inland WITH elevation like west Milford (over 1,000 feet in some parts) could definitely be looking at a snow/sleet to snow scenario with 20" or more

[ace0927]

I agree and think a rain to snow scenario is more likely. Besides Xmas 2002 and Dec 2003, we had a few of those back in the 90s... notably Nov 95, Mar 96...and a couple in 93-94 also.

alex- what dec 2003 event are you talking abt?

[A-L-E-X]

Very reasonable Ray and this is my thinking as well. GFS bufkit supports you as well

2-4 or 3-6 was my thinking also (read above post) wiht 1.5 QPF 0.5 as snow with 8:1 ratios (perhaps 10:1 in northern parts of the city.)

[A-L-E-X]

alex- what dec 2003 event are you talking abt?

Not the blizzard, Ace.... this came after that. It was a minor deal..... 2-4 or 3-6 I think.

[jconsor]

The problem is the models tend to underdo CCB precip in rapidly developing systems and instead show a broader but weaker QPF max. So what is depicted as 0.5" QPF could easily be double if you're sitting under the CCB, and half if you're not. In the 12/25/2002 storm, eastern Queens and Nassau County were under the CCB and got more than double as much snow as forecast - 8-11" in the max band.

I agree and I still think our "best case" scenario is probably 50/50 rain/snow but even that is being highly optimistic. Based on how we've typically done in backside snow situations, I would say 67/33 rain/snow is a safer bet. So if we had 1.5 QPF, 0.5 as snow would be the best we should expect, and probably 8:1 ratios.

[ace0927]

Not the blizzard, Ace.... this came after that. It was a minor deal..... 2-4 or 3-6 I think.

but that was front end snow and then rain

http://www.njfreeways.com/weather/2004/14-Dec-03.html

[A-L-E-X]

That definitely sounds legit....this thing really tightens up as it pulls away and turns to snow. I think even Monmouth county in NJ could easily see 6"+. arreas not too far inland WITH elevation like west Milford (over 1,000 feet in some parts) could definitely be looking at a snow/sleet to snow scenario with 20" or more

Haha West Milford is the snow capital of NJ! Not so far west that it gets screwed in bombing coastals to the east and just far enough west and enough elevation to totally kill the borderline scenarios! I wonder how they did in Dec 92 and Mar 93?

[famartin]

The problem is the models tend to underdo CCB precip in rapidly developing systems and instead show a broader but weaker QPF max. So what is depicted as 0.5" QPF could easily be double if you're sitting under the CCB, and half if you're not. In the 12/25/2002 storm, eastern Queens and Nassau County were under the CCB and got more than double as much snow as forecast - 8-11" in the max band.

This is why my upper limit is 6" and not 4". Still lots of uncertainty about exactly where that CCB sets up and what its staying power will be. I think NYC got 6" with the 12/25/02 CCB.

[A-L-E-X]

The problem is the models tend to underdo CCB precip in rapidly developing systems and instead show a broader but weaker QPF max. So what is depicted as 0.5" QPF could easily be double if you're sitting under the CCB, and half if you're not. In the 12/25/2002 storm, eastern Queens and Nassau County were under the CCB and got more than double as much snow as forecast - 8-11" in the max band.

Wow, I didnt realize some places got close to a foot with that. I agree with you that the models tend to "smooth" qpf fields (we saw this with Dec 26, 2010 also) and with these rapidly intensifying systems we see much more banding with "haves" and "have nots." Would the higher res models do much better with these? Perhaps looking at the MM5 once we're within 24 hrs of the event would give us a better idea as to where these might set up.

[SnowGoose69]

The problem is the models tend to underdo CCB precip in rapidly developing systems and instead show a broader but weaker QPF max. So what is depicted as 0.5" QPF could easily be double if you're sitting under the CCB, and half if you're not. In the 12/25/2002 storm, eastern Queens and Nassau County were under the CCB and got more than double as much snow as forecast - 8-11" in the max band.

I'm trying to figure out why the seem to show such a nasty CCB on this event...it seems to linger overly long on the GEM and it has shown the same signature on runs of other models as well....the CCB was forecast okay by the GFS in the 12/25/02 storm but the GFS forecast of snow behind the storm was largely ignored by HPC and the NWS

[TheTrials]

model diag. and disco from HPC

DEEPENING SYSTEM TRACKING FROM THE WRN GULF INTO WRN ATLC...

PREFERENCE: 00Z ECMWF/12Z GFS COMPROMISE LEANING 2/3 TO 3/4

TOWARD THE 00Z ECMWF

MOST 12Z GUIDANCE REINFORCES THE DEVELOPING BEST CLUSTER OF SOLNS

WITH THE MID LVL EVOLUTION... WITH A FAIRLY COMPACT CLOSED LOW

REACHING THE VICINITY OF NRN ALABAMA BY F48 EARLY WED AND TRACKING

NEWD THEREAFTER. THE UKMET AND CANADIAN REG GEM BOTH COMPRISE

THIS MAJORITY CLUSTER. THE CANADIAN GLBL IS MORE RELUCTANT TO

CLOSE THE MID LVL LOW BUT TROF TIMING COMPARES WELL TO CONSENSUS.

THE NAM IS THE ONE SUSPECT SOLN WITH A MID LVL TROF EVOLUTION THAT

IS SLOWER/MORE AMPLIFIED THAN MOST OTHER GUIDANCE... ASIDE FROM

THE 09Z SREF MEAN THRU TUE. ALSO THE NAM SFC EVOLUTION DOES NOT

COMPARE WELL TO OTHER GUIDANCE LATE WED-WED NIGHT AS IT HOLDS BACK

THE SWRN PART OF THE SFC SYSTEM WHILE TRACKING ITS WRN ATLC LOW

EWD OF MOST GUIDANCE. GIVEN TYPICAL NAM BIASES THE 12Z NAM FCST

WILL BE CONSIDERED THE LOWEST PROBABILITY SCENARIO.

AMONG THE NON-NAM SOLNS THERE ARE STILL SOME LINGERING

TIMING/TRACK DIFFS FROM THE SOUTHEAST INTO THE WRN ATLC. THE GFS

REMAINS ON THE FASTER SIDE OF THE ENVELOPE DURING WED-THU... WITH

THE CMC CLOSEST TO THE GFS TIMING. NOTE AGAIN THAT THE CMC IS A

LITTLE WEAKER THAN THE PRIMARY CLUSTER ALOFT AT SOME FCST HRS.

MEANWHILE BY WED NIGHT-THU THE 00Z ECMWF LEANS A BIT TO THE WRN

SIDE OF THE SPREAD. THE 12Z UKMET ALSO SHOWS A FAIRLY WWD TRACK

BUT SOME OF ITS PRIOR RUNS HAVE BEEN WWD EXTREMES AND THE NEW RUN

SEEMS TO HAVE ADJUSTED A LITTLE EWD TOWARD CONSENSUS. GIVEN THE

REASONABLE CONTINUITY OF AN INTERMEDIATE SOLN AND CURRENT TRENDS

IN THAT DIRECTION... WILL FAVOR SUCH AN IDEA BY WAY OF A 00Z

ECMWF/12Z GFS COMPROMISE THAT IS 2/3 TO 3/4 TOWARD THE 00Z ECMWF

DUE TO QUESTIONABLY FAST TIMING OF THE GFS.

[meteorjosh]

less than 48 hours out for many and still so much uncertainty, when can we expect to see any of the surface players on US charts, this forecast is going to require logic and experience, and until we start approaching nowcast time I am really not paying much attention to any model's details regarding QPF and temp profiles, and when I do begin paying attention it will be to the high res guys...I of course have that luxury as no one needs me to make a call at this point

with that I say good luck to the Mets on this board and I hope someone...whether it be C PA, E PA, NNJ, NYC/LI, interior NY or SNE...gets a memorable event (in a good way, which I guess means an extensive CCB and as cold as possible column temps)

on a side note, having lived in Manhattan much of my life I tend to be very conservative in situations like this, and if we do get slop I just hop a train up the Hudson for my snow fix