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12/26-12/28 Potential Snow Threat


CooL

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IIRC the December 2010 storm was a disaster (OTS) and within 24 hours the models flipped to what actually happened. Not that it'll happen again, but you never know.

...It was more like 60 hours out. The first model to flop was the 12z NAM...I remember it so vivdly.

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Well, we'll have to see what January has in store. 18z atrocious for the entire area.

There is a follow-up storm forming in the Mississippi/Tennessee Valley area Saturday the 29th with much colder air in place...-10C 850s over NYC on the 18z GFS and a storm brewing down south. Could we close the year with a New Year's snowstorm after seeing some light snow on Christmas?

I definitely think the pattern holds some promise, and all the models are showing a PNA spike near the New Year which should bode well for us. Tropical forming argues for a wintry stretch between December 25-January 15 this time around, so one of these storms should track favorably.

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IIRC the December 2010 storm was a disaster (OTS) and within 24 hours the models flipped to what actually happened. Not that it'll happen again, but you never know.

That was more of a complicated situation though with multiple interacting shortwaves and one was in data sparse NW Canada til late, as soon as that got sampled the models caught on. This case the best we can probably hope for is that the upper disturbance winds up less amplified over the Rockies and Plains than the models currently are thinking, if that happens the system would go negative later.

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IF this does come to fruition....it proves that the pattern and modeling TRENDS with that pattern are much more reliable than what a model SHOWS....and how for the most part the modeling even beyond just 48 hours can be used best to give an idea as to what type of storm and approximate timing/direction it is headed.....not specifically what states and counties get snow or rain, etc

From 96/120-240 hrs there is the Euro ensemble mean and the OP Euro vs everyone else. There seems to be

very little use for even the OP GFS at this range, though the ensemble means can have some valuable

teleconnection info at times.

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From 96/120-240 hrs there is the Euro ensemble mean and the OP Euro vs everyone else. There seems to be

very little use for even the OP GFS at this range, though the ensemble means can have some valuable

teleconnection info at times.

I think that too many people, too many times....myself included...look at the GFS and if its maybe within the 140 hour range or so...feel as if it is catching on to something and zeroing in on the outcome. Could it be close to what becomes reality sometimes ? Sure....lottery numbers that we pick may come very close to but....we know what we end up getting

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I think that too many people, too many times....myself included...look at the GFS and if its maybe within the 140 hour range or so...feel as if it is catching on to something and zeroing in on the outcome. Could it be close to what becomes reality sometimes ? Sure....lottery numbers that we pick may come very close to but....we know what we end up getting

It's disappointing that after all this time they couldn't make the GFS more useful at those longer ranges.

I can still remember the old post 84 hr truncation problems years ago that DT always used to rant about.

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I think that too many people, too many times....myself included...look at the GFS and if its maybe within the 140 hour range or so...feel as if it is catching on to something and zeroing in on the outcome. Could it be close to what becomes reality sometimes ? Sure....lottery numbers that we pick may come very close to but....we know what we end up getting

Once inside 108 hours or so I trust the GFS increasingly as time goes by. Prior to that time its subject to major changes and volitility from run to run. Its still dangerously volatile even from 48-96 at times, especially with Miller A type setups, Miller Bs it seems to generally have less wild changes inside 5 days.

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Amazingly poor trend on the GEFS today. Look how less dominant the ridge is over Central Canada at 108 hours. It is now an extension of a North Atlantic ridge -- exactly what we've been seeing all fall.

Todays GFS: http://www.meteo.psu.edu/~fxg1/ENSHGTAVGNH_18z/f108.gif

Last Nights GFS: http://www.meteo.psu.edu/~fxg1/ENSHGTAVGNH_0z/f120.gif

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I am not buying the center bombing out all the way to the lakes . The block is there , some runs have it stronger and others have it weaker .

A surface reflection will come up west into the Tenn Valley , IT SHOULD DIE and the primary shouldnt continue to deepen all the way to Buffalo . A secondary should show up off the mid atlantic coast . I dont buy the JMA or Canadian idea of a full fledged snowstorm ,BUT I dont buy 50 and rain either . I am hopeful tonites 0z runs come fruther east which is more in line with there Ensembles .

If I am wrong it will not be the first time .

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For those that have been around for awhile, most times during the 120-168 HR period, it's a good sign if you see someone's first call image with a foot of snow throughout VA. From my experience, the best storms for the metro are usually identified on several inconsistent runs (normally 12z or 00z) with majority of GFS runs showing a VA/DC hit. Once within the 90-120 Hr period, a NW trend ensues. Also, NOGAPS is basically useless. SREF mean from PSU website is king IMO.

Once inside 108 hours or so I trust the GFS increasingly as time goes by. Prior to that time its subject to major changes and volitility from run to run. Its still dangerously volatile even from 48-96 at times, especially with Miller A type setups, Miller Bs it seems to generally have less wild changes inside 5 days.

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For those that have been around for awhile, most times during the 120-168 HR period, it's a good sign if you see someone's first call image with a foot of snow throughout VA. From my experience, the best storms for the metro are usually identified on several inconsistent runs (normally 12z or 00z) with majority of GFS runs showing a VA/DC hit. Once within the 90-120 Hr period, a NW trend ensues. Also, NOGAPS is basically useless. SREF mean from PSU website is king IMO.

Alot of those upstream rules work. One big no no for this area is if OKC sees a snowstorm upstream, which they are appearing they will with this event, its extremely rare for this area to see snow from the same system that gives OKC a snow event, generally that means the system is cutting west or its a suppressed southern wave.

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Amazingly poor trend on the GEFS today. Look how less dominant the ridge is over Central Canada at 108 hours. It is now an extension of a North Atlantic ridge -- exactly what we've been seeing all fall.

Todays GFS: http://www.meteo.psu...NH_18z/f108.gif

Last Nights GFS: http://www.meteo.psu...GNH_0z/f120.gif

Cool comparison. Amazing to see on the spaghetti plots how last night there were only a few spaghetti strand 534mb contours (or whatever pressure level that chart plots) in southcentral Canada at 120hours. Today they are almost all clustered there for that time period. Pretty significant 12 hour change. And it once again highlights the precariousness of ensemble modeling.

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Definitely true. Historically, most major I-95 hits were modeled in the medium range to either miss east or hit south (VA/MD/NC). Very rare to see a NW solution correct SE.

The enitity that modeling is playing catchup with is the stagnancy of polar airmasses. Forecasted high temps have been creeping up all week. Confluence over the NE has been modeled too strong.

Alot of those upstream rules work. One big no no for this area is if OKC sees a snowstorm upstream, which they are appearing they will with this event, its extremely rare for this area to see snow from the same system that gives OKC a snow event, generally that means the system is cutting west or its a suppressed southern wave.

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Definitely true. Historically, most major I-95 hits were modeled in the medium range to either miss east or hit south (VA/MD/NC). Very rare to see a NW solution correct SE.

The enitity that modeling is playing catchup with is the stagnancy of polar airmasses. Forecasted high temps have been creeping up all week. Confluence over the NE has been modeled too strong.

There was one event that notably corrected SE in either 09-10 or 10-11 (I think 09-10)...everything sucked, the NAO/confluence yet somehow the storm took a coastal track, 5-7 days out every model was a cutter and had been one since day 10. I remember posting continulously there was no way the storm could go to the coast.

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Migh make sense given the closed H5 trof goes negatively tiled really early and appears to be much stronger than previously modeled. We all know how people will yell and scream "don't judge until the energy reaches land so that it can be sampled appropriately"...well it's been sampled alright....

SREFS tonight have a legitimate lakes cutter. Drive the storm into the Ohio Valley.

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Migh make sense given the closed H5 trof goes negatively tiled really early and appears to be much stronger than previously modeled. We all know how people will yell and scream "don't judge until the energy reaches land so that it can be sampled appropriately"...well it's been sampled alright....

It's not looking good. Euro has never shown a snowy solution for us and the GFS has been somewhat consistent and trending away from any type of 50/50 helping us.

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Migh make sense given the closed H5 trof goes negatively tiled really early and appears to be much stronger than previously modeled. We all know how people will yell and scream "don't judge until the energy reaches land so that it can be sampled appropriately"...well it's been sampled alright....

As Ron Darling would say when people say it is too early to judge a ballplayer: 'Sometimes you know.'

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