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December pattern/forecast thread

weathafella

By weathafella,
in New England

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Typhoon Tip

Typhoon Tip

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44 minutes ago, snowgeek said:

LARGE CHANGES WERE NECESSARY IN THE TEMPERATURE OUTLOOK, DUE TO A HIGHLY AMPLIFIED RIDGE FORECAST OVER THE BERING SEA WITH A DOWNSTREAM AMPLIFIED TROUGH ACROSS THE CONTINENTAL U.S. LIKELY PERSISTING THROUGH THE FIRST HALF OF DECEMBER. THIS LONGWAVE PATTERN YIELDS A MUCH COLDER OUTLOOK ACROSS THE CONTINENTAL U.S. AND ALASKA THAN WHAT THE DYNAMICAL MODEL GUIDANCE INDICATED AT MID-MONTH.

this paragraph, right here, that you've bolded is why I've always been sort of on the fence with 86'ing winter patterns downstream over N/A based on the "Aleutian Low" phenomenon.  

there's merit to that argument...of course. BUT, more importantly the AL shares domain space with the BSR phenomenon.  both's axis tend to wobble east and west and those perturbations tend to send signals downstream over the continent often enough to make the correlation between either to distributions of temperature and precipitation anomalies less than clean and clear.  I have seen noreasters on the EC with and without stronger SPVs near the Aleutians ... 

it really just comes down to wave lengths, nothing more.  you can have a 3 wave, or 4 wave, or 5 wave pattern around the hemisphere.  AL may be bad for 4 wave patterns, but good for 5 wave (as far as what it means for us here...)  I don't think we can really see an AL modeled and autopilot freak out. 

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CoastalWx

CoastalWx

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I think people just need to understand it's sort of a high stakes pattern. We are near the battle line. It could be an awesome run, or something where we we're just a bit too far southeast for the good stuff. Saying that a pattern is good or bad is basically just summarizing the overall 500mb look. We simply cannot determine the exact nuances the govern cyclogenesis in the near term. So, that's why some patterns that initially look good may not work out, or in the case of 2015 look decent overall.....but wound up giving us a record run. 

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Typhoon Tip

Typhoon Tip

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again, the "start" (trend) of this was in the 00z run... 

whether this turns out to be a red herring or the GFS ' last three cycles are onto something will be interesting to test.   i saw some suggestion actually in the 00z GGEM that it was also trying to go more progressive... it's overall evolution is typically absurd looking still, but it is seemingly ready to acknowledge the southern height wall and deflecting things more E there - we'll see how this run turns out.

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Typhoon Tip

Typhoon Tip

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6 minutes ago, Ginx snewx said:

Dec 6- 8th 1996 came to mind again looking at the 12Z GFS, now that would be a great surprise

96120800.gif

gfs_T850_us_24.png

 

that was an amazing storm... 36 hours there were two of them - if i got it right.  Jim Cantore of the WC was out in Worcester for the 2nd one in thundersnow.  

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4 minutes ago, ORH_wxman said:

 

Yeah the 2nd one looks kind of similar to Dec 7, 1996...not the first one around 132 hours.

 

Either way, it's clown range being 7 days out.

honestly ... i don't think of D7 as 'clown range' 

i know, i know. it's subjective terminology and all that.  

but, fwiw, i think of d7's today as d10's around the year 2000 if that makes any sense. 

probably not, but when the teleconnectors are ganging up on a signal and a d7 seems to fit, it's less like a clown and more like one of the three stooges say. heh

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Typhoon Tip

Typhoon Tip

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anyway, funny we mentioned the 36 hour, 1996 series. 

typically, that's too close in time for theta-e recovering in the atmosphere.  we've seen countless times, wasted follow-up dynamics because some shrapnel of lead vorticity gobbled up all the water and dumped prolifically...then the dynamics arrive and it's windy snizzle.  that can happen... 

1996 was a freak couple of storms.  December and possibly March into early April are the times of years to bunch them together if your going to succeed in doing so (most likely) because there's usually a richer source of moisture at those particular times of years.  in '96' ...a late blooming NJ Model low/dynamics dumped a surprise 4-10" of cake batter on the region, and then some 18 to 24 hours later, there was another that did thunder snow bands.  in between, the sky remained gray, and there were grains in still air, with trees heavily stenciled with white/black contrast. it just felt sort of ominous.   no melt,...2nd system was wet snow on top and the between the two, power outages were common in the interior.  

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CoastalWx

CoastalWx

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3 minutes ago, Typhoon Tip said:

 

anyway, funny we mentioned the 36 hour, 1996 series. 

typically, that's too close in time for theta-e recovering in the atmosphere.  we've seen countless times, wasted follow-up dynamics because some shrapnel of lead vorticity gobbled up all the water and dumped prolifically...then the dynamics arrive and it's windy snizzle.  that can happen... 

1996 was a freak couple of storms.  December and possibly March into early April are the times of years to bunch them together if your going to succeed in doing so (most likely) because there's usually a richer source of moisture at those particular times of years.  in '96' ...a late blooming NJ Model low/dynamics dumped a surprise 4-10" of cake batter on the region, and then some 18 to 24 hours later, there was another that did thunder snow bands.  in between, the sky remained gray, and there were grains in still air, with trees heavily stenciled with white/black contrast. it just felt sort of ominous.   no melt,...2nd system was wet snow on top and the between the two, power outages were common in the interior.  

We actually had TSSN from the first low south of Boston over in interior SE MA(Taunton-Brockton area). That was a surprise 4-6" of pure mash potatoes when the call was down the drain. I had a slab of snow pasted on the side of my car that must have slowly slid down to the ground. It looked like a wall of paste from the roof of my car straight to the pavement. Could not tell where window, door, and base of my car ended lol.  Following storm was rain. 

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Typhoon Tip

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3 minutes ago, CoastalWx said:

We actually had TSSN from the first low south of Boston over in interior SE MA(Taunton-Brockton area). That was a surprise 4-6" of pure mash potatoes when the call was down the drain. I had a slab of snow pasted on the side of my car that must have slowly slid down to the ground. It looked like a wall of paste from the roof of my car straight to the pavement. Could not tell where window, door, and base of my car ended lol.  Following storm was rain. 

huh, follow-up'er was rain down there.  

yeah, it was mid size aggregate thunder storms for several ours on that 2nd one from Acton up through the Merr. Valley at college.  must have been 9::1 or even less... 10 or 12" of pure blue magic.  the kind you cleave the shovel into and it's a Nat geo special on interior Greenland looking -

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12 minutes ago, Dan said:

 

They had a power failure, which has now been corrected.  All products will be delayed approximately 3 hours.

that's how you know it's going to be an important run... 

we did a statistical analysis up at uml when i was an undergrad and found a like ... .8 and change correlation coefficient existed between outages and 'what people wanted to see' in models... granted, the sample size wasn't appreciably large given to the fact that 'modeling' was all over 20 years old at that time...still, creepy -

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dendrite

dendrite

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28 minutes ago, Typhoon Tip said:

honestly ... i don't think of D7 as 'clown range' 

i know, i know. it's subjective terminology and all that.  

but, fwiw, i think of d7's today as d10's around the year 2000 if that makes any sense. 

probably not, but when the teleconnectors are ganging up on a signal and a d7 seems to fit, it's less like a clown and more like one of the three stooges say. heh

I think you mean d10 today is like d7 in 2000.

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ORH_wxman

ORH_wxman

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1 hour ago, Typhoon Tip said:

honestly ... i don't think of D7 as 'clown range' 

i know, i know. it's subjective terminology and all that.  

but, fwiw, i think of d7's today as d10's around the year 2000 if that makes any sense. 

probably not, but when the teleconnectors are ganging up on a signal and a d7 seems to fit, it's less like a clown and more like one of the three stooges say. heh

 

Well I mean "clown range" in terms of operational model output...I definitely agree that you can ascertain a "signal" for a storm within 7 days...sometimes even at longer leads around D10. We do this all the time as you note...typically with teleconnections and ensembles.

 

But this specific evolution we're seeing on the GFS is clearly dependent on a bunch of moving parts like the timing of the Mexican ULL ejecting, etc, etc...we only know that there will be a solid trough over the Plains/Midwest at some point around D7...but parsing the specifics is probably a fool's errand at this lead time.

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