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NYC/PHL Jan 11-14 Threat Potential Part 3


am19psu

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Considering the Euro showed a decent hit today, the GFS is getting better at H5, and the NAM has SREF support, I'd go with a good event at the moment. I've heard the GFS isn't the best with east coast storms.

Now if the Euro goes east, the GFS would have more weight.

The GFS can be bad in the mid range. We're getting into GFS golden times. And the EC has been having trouble right around this time lately (48-72 hours before the event). Remember the EC flips.

Amounts are certainly not locked right now. This could go KU... or it could just be a moderate event.

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The GFS can be bad in the mid range. We're getting into GFS golden times. And the EC has been having trouble right around this time lately (48-72 hours before the event). Remember the EC flips.

Amounts are certainly not locked right now. This could go KU... or it could just be a moderate event.

Not saying the ECMWF isn't going to flip tonight...but the reason due to the flip was because the northern shortwave wasn't being sampled. This time, everything should have been properly sampled.

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Its still too far out to go too heavy with the mesoscales yet. Wait til the system is within 48 hours (so not until 12Z tomorrow at the earliest), then start giving the mesoscales more weight. Right now I'd go with a blend of the GFS and whatever the EC spits out.

Ray - you obviously seem to have a good grasp of when to use which models. Was wondering if you might comment on the thread I started on the main board asking about verification scores for the main models with regard to snowfall prediction performance in the NE US at different timepoints. Just curious to see if there is real data out there or if most people go with their experience/memory or something else.

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Not saying the ECMWF isn't going to flip tonight...but the reason due to the flip was because the northern shortwave wasn't being sampled. This time, everything should have been properly sampled.

That was the reason for the flip for the 12/26 event. But remember it flipped on the 12/19 non-event. At that time it had trouble with the southern shortwave as it came ashore.

Not saying its gonna do any flipping this time, but certainly something to think about.

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Craig Allen On-Air IncOK...this is w/o over analysis this evng b/c its going to waiver b&f a few times and no complete consensus yet amongst the players. So let's start with an easy 6. 12-18" is certainly attainable w/ ltng & thndr, howling winds- the works- again. All by Wed mrng at its closest apprch. Then slowly tapers down drg the day. Tonights data says "snow day!!!" for Wed. We'll see. :)
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Ray - you obviously seem to have a good grasp of when to use which models. Was wondering if you might comment on the thread I started on the main board asking about verification scores for the main models with regard to snowfall prediction performance in the NE US at different timepoints. Just curious to see if there is real data out there or if most people go with their experience/memory or something else.

I don't think they do any verification on *snowfall*. They *do* do verification on precipitation forecasts. I have been shown recent stats that the EC is king, barely. EC has a slight dry bias and the GFS has a slight wet bias. NAM.. well, it sucks (way too wet overall).

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The NAM has been good on most storms this winter but we're still not really into its strong range yet.

It looks like the 00z NAM is stronger with the mid level low which then tugs the surface low closer to the coast. This solution seems to be the farthest west one and is probably to far west and therefore its QPF is to high (at least for PA, NJ and DE).

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nuisance event? You must under the age of 20 because a 3-6 storm in the 80s and through the 90s was considered a solid snowstorm, its just past decade and the last 5 years that have fooled people.

Well a 3-6" doesn't close anything down like schools and businesses, which makes things worse for travelers. There's more accidents in these types of storm because people ignore the threat. And I know about the whole 80s, 90s thing, I brought that point up earlier today. I'm not expecting another 12" inch storm, 6" would do.

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Guys not to interupt your excellent discussion.....but regarding the NAM v GFS handling fo the vort lobe at 48 hours on the Jersey Shore:

The NAM tried 3 different times with 2 different s/w complexes to do the exact same thing and failed since Thursday. I posted one of the maps from the other night that looks comically similar to tonights 0z NAM. It was the 12z NAM that delivered a big hit on Friday before it vanished. The other models had the energy getting out ENE instead of riding towards NYC. That's our difference here again tonight.

And to add further - even the "east' models blew it in the end. Inside of 24 hours it just kept slipping further east ahead of the models which led to a big bust up here with actual storm snows. Instead of the CCB being on land, it was 200 miles offshore all within the last 12-18 hours of modeling.

Just things to watch. If the euro nudges east at all tonight it's time to really be concerned about an eastward jump.

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Well a 3-6" doesn't close anything down like schools and businesses, which makes things worse for travelers. There's more accidents in these types of storm because people ignore the threat. And I know about the whole 80s, 90s thing, I brought that point up earlier today. I'm not expecting another 12" inch storm, 6" would do.

3-6 does close schools, at least some times. Not all the time, granted. But not *never* either.

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Guys not to interupt your excellent discussion.....but regarding the NAM v GFS handling fo the vort lobe at 48 hours on the Jersey Shore:

The NAM tried 3 different times with 2 different s/w complexes to do the exact same thing and failed since Thursday. I posted one of the maps from the other night that looks comically similar to tonights 0z NAM. It was the 12z NAM that delivered a big hit on Friday before it vanished. The other models had the energy getting out ENE instead of riding towards NYC. That's our difference here again tonight.

And to add further - even the "east' models blew it in the end. Inside of 24 hours it just kept slipping further east ahead of the models which led to a big bust up here with actual storm snows. Instead of the CCB being on land, it was 200 miles offshore all within the last 12-18 hours of modeling.

Just things to watch. If the euro nudges east at all tonight it's time to really be concerned about an eastward jump.

Good post. Something that keeps my eyebrows rasied is the SREF having so many members, of so many dynamic and modeling schemes, showing the big wrapped up solution. Something is up here...I guess we just don't really know what's going on yet. The 00z globals have all improved with their H5 setups so far (GFS/GGEM)...but they aren't jumping to the NAM yet. They both seem improved in getting the CCB to develop faster, though.

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It looks like the 00z NAM is stronger with the mid level low which then tugs the surface low closer to the coast. This solution seems to be the farthest west one and is probably to far west and therefore its QPF is to high (at least for PA, NJ and DE).

So is Mt. Holly discounting this solution?

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Good post. Something that keeps my eyebrows rasied is the SREF having so many members, of so many dynamic and modeling schemes, showing the big wrapped up solution. Something is up here...I guess we just don't really know what's going on yet. The 00z globals have all improved with their H5 setups so far (GFS/GGEM)...but they aren't jumping to the NAM yet. They both seem improved in getting the CCB to develop faster, though.

I look at the 500mb depictions before I even look at the surface, and I agree that they all seemed to be more amplified/stronger. There's definitely still time for a "surprise", but I really like what I'm seeing on the upper air charts in terms of delivering improved energy and divergence aloft for the developing storm. I think it's likely that it's deepening fast at our latitude-we just have to hope it's close enough to deliver the goods.

Personally, I'd rather also be on the western edge of the heavy precip on these coastal events, because that's often where the best banding sets up. I was progged on almost every model to have more liquid precip than E NJ on 12/26, yet some there saw close to 10" more snow than me. I was on the western end of the heavy precip on the models for 12/19/09, and yet we got rocked here for hours.

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HPC

..LOW PRESSURE DEEPENING OFF THE MID-ATLANTIC/NORTHEAST COAST

TUE-WED...

PREFERENCE: BEFORE 00Z WED...NAM OR 12Z ECMWF

AFTER 00Z WED...2/3 12Z ECMWF TO 1/3 GFS

THE NAM AND 12Z ECMWF ARE SIMILAR THROUGH 00Z WED...WITH THE GFS

SLIGHTLY EAST OF BOTH SOLUTIONS. HOWEVER...THEREAFTER THE

NAM...DUE TO ITS DEEPER AND SLOWER SOLUTION UPSTREAM...PULLS THE

LOW INCREASINGLY TOWARD THE WESTERN EDGE OF THE GUIDANCE...WHILE

THE GFS REMAINS CLOSE BUT SLIGHTLY EAST OF THE ECMWF LOW TRACK

THROUGH THE REMAINDER OF THE PERIOD. WHILE NO OBVIOUS PROBLEMS

EXIST WITH THE NAM'S SOLUTION LATE IN THE PERIOD...INCLUDING FROM

INITIALIZATION...ITS LOW TRACK LIES WEST OF NEARLY THE ENTIRE

DETERMINISTIC/ENSEMBLE GUIDANCE ENVELOPE AFTER 12Z WED AND THUS IS

DEEMED AN OUTLIER. AMONG THE REMAINING GUIDANCE...THE ECMWF HAS

SLIGHTLY BETTER ENSEMBLE SUPPORT THAN THE GFS. THUS...RECOMMEND

LEANING TOWARD THE ECMWF.

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I look at the 500mb depictions before I even look at the surface, and I agree that they all seemed to be more amplified/stronger. There's definitely still time for a "surprise", but I really like what I'm seeing on the upper air charts in terms of delivering improved energy and divergence aloft for the developing storm. I think it's likely that it's deepening fast at our latitude-we just have to hope it's close enough to deliver the goods.

Personally, I'd rather also be on the western edge of the heavy precip on these coastal events, because that's often where the best banding sets up. I was progged on almost every model to have more liquid precip than E NJ on 12/26, yet some there saw close to 10" more snow than me. I was on the western end of the heavy precip on the models for 12/19/09, and yet we got rocked here for hours.

great post. plus, Upton has been throwing out the op in favor of the ensembles, and using a blend of them, in addition to the Euro/nam/rgem for their reasoning. i think we're still in for a solid 6-12 event (at least), with heavy snows during the wed AM rush...

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