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2/29 - 3/1


NEG NAO

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This has to be one of the weirdest strong medium range signals I've seen, both on the ECM and the ensembles... apparently it's strong with a snowstorm signal, while the 12z GEFS members show mostly an amplified storm with rain, not one of them anything close to the ECM. One way to look at this is that it's good since we don't want to be in the bullseye for snow in the medium range, but given this winter's history and the unfavorable pattern still in place I'm having a real hard time seeing how this becomes a snowstorm.

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Yeah but that was a storm that the models locked into several days out and didn't waver until within 48 hours, then everything fell apart. But most forecasters kept holding on that we'd still see significant snows. Keep in mind it was supposed to be a 48 hour+ event with a break in between and the storm doing a loop and stalling off the coast. Very unique situation like 2/26/10 that probably won't ever be repeated.

The other models have been hinting at this for days, It comes and it goes. As some have said, its been on the Euro ensembles for many runs now and as one met pointed out, the GEFS solution doesn't even make since given the 1030 mb high in place. Even so, I am just as skeptical as the next person.

The setup looks similar to that of 2001, without knowing that much about it. I am just going by the basic surface features. (Main low cutting through the TN valley, secondary popping but too far east, NY misses the big snows). This...and the time of year.

http://www.hasbrouck...s01/snow1.shtml

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There are some obvious factors that I don't like:

-Progressive troughing in the west likely disallows much amplification and even if it does, it's a quick hitter or out to sea because of the kicker.

-No blocking and +NAO, we're basically relying on perfect timing for a phase of the short waves and correct track

-Very little true cold air available due to PV over western Alaska and PAC dominated regime

-Overall evolution of this run seems odd because of the lack of amplification, wouldn't think the storm blows up like that unless it can slow down and get some deeper tropical influx involved

In my view, we have a LONG way to go before calling this a real threat.

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There are some obvious factors that I don't like:

-Progressive troughing in the west likely disallows much amplification and even if it does, it's a quick hitter or out to sea because of the kicker.

-No blocking and +NAO, we're basically relying on perfect timing for a phase of the short waves and correct track

-Very little true cold air available due to PV over western Alaska and PAC dominated regime

-Overall evolution of this run seems odd because of the lack of amplification, wouldn't think the storm blows up like that unless it can slow down and get some deeper tropical influx involved

In my view, we have a LONG way to go before calling this a real threat.

Although there's some obvious differences, the progressive ridge in the west sounds very much like last weekend's storm and how the GFS tried to turn it into a huge storm with the progressive ridge one of many factors working against it. While this far out the potential isn't zero, given the unfavorable pattern and this winter's history of producing failures, it's hard to call this a real potential at this time. If we were 84 hours out with the storm still on the models, then there'd be much more to talk about.

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I really don't understand why so many folks here this storm is impossible - not saying its going to verify - BUT until the GFS stops showing a different solution every other run or the EURO starts showing an inland solutuion have to side with the most consistent model and its ensembles IMHO

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There are some obvious factors that I don't like:

-Progressive troughing in the west likely disallows much amplification and even if it does, it's a quick hitter or out to sea because of the kicker.

-No blocking and +NAO, we're basically relying on perfect timing for a phase of the short waves and correct track

-Very little true cold air available due to PV over western Alaska and PAC dominated regime

-Overall evolution of this run seems odd because of the lack of amplification, wouldn't think the storm blows up like that unless it can slow down and get some deeper tropical influx involved

In my view, we have a LONG way to go before calling this a real threat.

The shorter wavelengths make the progressive troughing not nearly as much of a problem, IMO. It's not a very cold pattern, but there is cold air available in Canada. The lack of blocking will definitely hurt us, thiugh.

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I no longer have access to the JMA beyond 144 but it looks completely different from the ECM and its ensemble means at 144hrs..

Does it show a coastal low in the 168-192 time frame?

Yes it does. It looks like the nogaps. A little east of the Euro. Has a 980's low east of Cape Cod at hour 192 and the whole area already received .50"-.75" of precip.

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I really don't understand why so many folks here this storm is impossible - not saying its going to verify - BUT until the GFS stops showing a different solution every other run or the EURO starts showing an inland solutuion have to side with the most consistent model and its ensembles IMHO

ECM means are not nearly as AMPED as what the ECM OP was..

post-342-0-33728100-1329945332.gif

Looks like from 168-192 the system would move ENE on the means...from SE KY at 168

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ECM means are not nearly as AMPED as what the ECM OP was..

Looks like from 168-192 the system would move ENE on the means...from SE KY at 168

That's because it's an ensemble mean, and it probably has many members with different positions an different intensities with the storm, which is what the Ensemble Mean does. It takes the mean of all of these individual members.

The image you posted above is a strong signal for a storm being that it is an Ensemble mean, and it is a 192 hour Ensemble Mean.

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It's painful even looking at those maps as we all know it's probably not going to happen.

Probably just bad as the GFS was for last weekend - 3 runs out in the medium range had a huge storm which in reality stayed way to our south. With this one run, even if this snowstorm doesn't show up again on any more models, some people's expectations have probably gone up for this possible storm.

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That's because it's an ensemble mean, and it probably has many members with different positions an different intensities with the storm, which is what the Ensemble Mean does. It takes the mean of all of these individual members.

The image you posted above is a strong signal for a storm being that it is an Ensemble mean, and it is a 192 hour Ensemble Mean.

Having seen the spaghetti plots, there are many members of the euro ensembles that are just as amped and even more amped then the operational.

Like you said, there are over 50 members of the ensembles and a lot of them show nothing and the mean on a day 7 product will reflect that.

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Probably just bad as the GFS was for last weekend - 3 runs out in the medium range had a huge storm which in reality stayed way to our south. With this one run, even if this snowstorm doesn't show up again on any more models, some people's expectations have probably gone up for this possible storm.

The euro had 2-3 runs in a row as well, which bought the low up the coast and affected NYC-BOS. People keep forgetting that.

Only the GGEM and the Nogaps never gave our area snow.

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The euro had 2-3 runs in a row as well, which bought the low up the coast and affected NYC-BOS. People keep forgetting that.

Only the GGEM and the Nogaps never gave our area snow.

the euro had the storm as a coastal many days before the event then went south and stayed there for several days until the storm - the gfs then followed the euro 3 days prior to the storm

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I'm already willing to say that the 18z GFS will look nothing like the 12z GFS.

Look at how much less the northern stream shortwave in western Canada is digging in the 18z compared to the 12z at 500 mb at 120 hours.

EDIT: Overall, the 18z GFS seems more amplified with more northern stream interaction with the southern branch.

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GFS is south by about 200-300 miles with the Low Pressure, and is significantly weaker with the Low Pressure area.

At almost 180 hours out, there's going to be plenty of changes from now until the short range, but even so the GFS is even worse than the ECM considering that there's practically no western ridging and any signs of blocking, and just as we've seen so many times this winter, rain or no storm are more likely outcomes than a snowstorm.

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18z GEFS mean looks very similar to the Euro ENS, strong signal for a coastal storm with a 1011 mb low off the coast and .25-.5" of precipitation over the area in a 12 hour period. There is more precipitation before and after this frame that falls because of this storm. The mean looks nothing like the operational. There probably are a few hits in the GEFS with the higher precipitation amounts near the coast.

18zgfsensemblep12180.gif

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