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Christmas/Post Christmas Threat

Nikolai

By Nikolai,
in Mid Atlantic

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aldie 22

aldie 22

Posted
Posted

just read his site. he is very bullish on the threat.

at 9am he was...thing is this event is still so far out there in time that we all know things will change...maybe for the better maybe not. I would imagine todays runs are a group of many possibilities with this thing so we just keep on watching. I am sure there is going to be plenty of joy and heartbreak for lots of us with this thing.

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Ender

Ender

Posted
Posted

Can you explain? The trend last night seemed to be pretty friendly

I know...and I'm thankful for the brief moments of happiness the models have accorded me. However the following is troubling:

  • The GFS has certainly backed off it's mega storm ideas of a few days ago.
  • The GEFS is starting to show a more and more southerly track, especially for the closer in forecast hours for instance:

00zgfsensemblep12120.gif

This^ has become this

12zgfsensemblep12108.gif

Same idea 12hr later:

00zgfsensemblep12132.gif

Is now more like this...

12zgfsensemblep12120.gif

Since all models seem to want to take this thing NE rather than NNE up the coast we really need it to exit as far north as possible (not yesterday's 18Z GFS, though). An exit in central SC isn't going to help us enjoy much in the way of over running...and, unless we find a way for the resulting surface, and H8, low to head up through the piedmont, we're going to have a pretty tough time here.

  • While last night's EC was in favor of a NC to NJ hugging system, that level of phasing appears to have been abandoned by the 12Z today. This is obviously not an encouraging trend, but, in making mattters worse it's still one of our most promising runs from today's 12Z. Having said that, we need to keep in mind that the EC hasn't exactly been spectacular this cold season along the SE and MIdAtl coast. Especially not between forecast hours 132 and 168...and that even excuses last week's one run disaster for forecast hour 72, which would have been yesterday's 6" at IAD.
  • The GGEM and JMA...two models that simply treasure the opportunity to phase and explode...especially in the OV and SE or coastal plane up through NC and VA...both are consistently disinterestted in this system.

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PhineasC

PhineasC

Posted
Posted

i think people can make a much stronger argument for this not being that big of a deal (except for the timing) than anything else at the moment. the seasonal trend as well as of course climo argues against it being a prolific snowmaker etc. i'd put all my eggs in the potential overrunning and hope things look better soon. the euro is probably still in an OK position for that part, as overrunning in my remembrance more often than not shifts north into gametime as opposed to the other way around.

Thanks for the analysis. How are things looking for CT?

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Ender

Ender

Posted
Posted

Well the Euro seems to imply a low traversing the florida panhandle and coming up through the outer banks. Frankly a 995 MB low over the outer banks typically yields good results for this area. I don't think it's time to throw in the towel just yet. I thought miller B's typically don't make it down to the florida panhandle. A typical miller B is centered over Tennessee, or northwest Georgia, and jumps the mountains to the coast. I guess we are splitting hairs here.

At the same time it should be noted that....

  • The OP EC had a 1004mb low centered very near the coastal border of SC/NC at 0Z on Sunday. It now has a 1008mb low over the central coast of GA.
  • The 0Z OP had a sub 996mb low very barely east of ECG/ORF at 12Z on Sunday, that's been replaced by a 996mb low about, hm, 75mi? ESE of HAT. As the low 12Z low passes the latitude of ORF its a good 200mi further east than the previous run.
  • Instead of a 988mb low just feet to the east of ACY at 18Z on Sunday the today's 12Z EC has 988mb low hundreds of miles to the east of Chincoteague.
  • We tend to do best up here when the surface low travels along or inside the Outerbanks, not well, well, east thereof. The track as shown is going to feature an 850mb low that too far east of our latitude while the low's exiting SC and, sadly, being drawn in even more tightly to the east as the explosive developed happens, but just a bit too far east to be of benefit to us.

At least IMO, of course.

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Terpeast

Terpeast

Posted
Posted

What exactly is "phasing"?

When the trough axes of the southern/pacific stream and the northern stream align into one trough axis, and both streams combine (phase) into one trough that swings around and south of the polar vortex. When the phase happens, the trough tends to go neg tilt and the sfc low bombs.

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Bob Chill

Bob Chill

Posted
Posted

Even with the most recent model runs, odds of at least some overrunning in the MA appear to be pretty good. It's going to be a juicy system moving across the country and will tap the gulf as it makes it's way across. Still a lot of time for just about any solution. As long as the front end overrunning stays, I'll be very happy. Sure a MECS+ on Xmas weekend would be a weenie dream but I have no problem at all with a 2-4" storm. Snow on Xmas around these parts is really rare so anything would be a treat.

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Kevin Druff

Kevin Druff

Posted
Posted

What exactly is "phasing"?

When the trough axes of the southern/pacific stream and the northern stream align into one trough axis, and both streams combine (phase) into one trough that swings around and south of the polar vortex. When the phase happens, the trough tends to go neg tilt and the sfc low bombs.

In layman's terms: 2 areas of energy (shortwaves) come together and form one combined area of energy.

What Terpeast means when he says the trough "goes negative tilt" is that the axis of the storm will run from the Northwest to the southeast versus a progressive tilt of Northeast to southeast or neutral tilt north to south.

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psuhoffman

psuhoffman

Posted
Posted

I am upset by the trends, not that the models show a miss right now. I wanted to see the storm trend south not east. The problem is the models are morphing this storm into a northenr branch dependent storm again. Much less WAA snows initially and much more a storm dependent on a phase. In a nina patter that is a bad proposition for our area. However, I am not as down on this as the last storm because there is some pacific jet energy this time and it is coming across west to east...if that is a little further north then the models are showing it could facilitate a phase faster then what the 12z models indicate. That is what we need.

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Ender

Ender

Posted
Posted

Thanks Ender...hopefully 0z will show some other trends that are in our favor.

Don't get me wrong, I'm desperate for a decent storm. I'd be willing to sacrifice by 88yo grandmother for at least 4" on Christmas. Well, she's not actually doing all that well, so I guess I should sweeten the deal. I could throw in my little brother, and his dog that keeps crapping all over my house...and my dad...I've been tired of his sarcasm for decades now.

(No, I wouldn't really sacrifice all that just for a 4" snowstorm. I love my grandma way too much)

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ravensrule

ravensrule

Posted
Posted

Don't get me wrong, I'm desperate for a decent storm. I'd be willing to sacrifice by 88yo grandmother for at least 4" on Christmas. Well, she's not actually doing all that well, so I guess I should sweeten the deal. I could throw in my little brother, and his dog that keeps crapping all over my house...and my dad...I've been tired of his sarcasm for decades now.

(No, I wouldn't really sacrifice all that just for a 4" snowstorm. I love my grandma way too much)

Wow i wish i was in your family, it sounds amazing :popcorn: .

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Ender

Ender

Posted
Posted

What exactly is "phasing"?

Imagine if you will a stream flowing along from west to east. It's a very smoothly flowing stream as the culvert it's in is one of those big wide concrete rivers they have in places like Las Vegas. Now imagine that there's side culverts that can dump into, or along side, the rushing river of rain water. Some jack--- dumps his 20 sewage tankers into one of those side culverts and the ensuing slurry rushes down to meet the swiftly flowing river of crisp clean rain water. The result is a beautiful tapestry of brown and clear, and at the area of greatest laminar flow gradient you get complex whirls and even deep vortexes in the water.

Well, it's not precisely like that as it has a lot more to do with the linking of jet exit regions, one to the northern and the other in a more southern stream of flow, with the result being a region that's particularly favored for surface low deeping via outstanding UL divergence.

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Midlo Snow Maker

Midlo Snow Maker

Posted
Posted

Don't get me wrong, I'm desperate for a decent storm. I'd be willing to sacrifice by 88yo grandmother for at least 4" on Christmas. Well, she's not actually doing all that well, so I guess I should sweeten the deal. I could throw in my little brother, and his dog that keeps crapping all over my house...and my dad...I've been tired of his sarcasm for decades now.

(No, I wouldn't really sacrifice all that just for a 4" snowstorm. I love my grandma way too much)

Imagine if you will a stream flowing along from west to east. It's a very smoothly flowing stream as the culvert it's in is one of those big wide concrete rivers they have in places like Las Vegas. Now imagine that there's side culverts that can dump into, or along side, the rushing river of rain water. Some jack--- dumps his 20 sewage tankers into one of those side culverts and the ensuing slurry rushes down to meet the swiftly flowing river of crisp clean rain water. The result is a beautiful tapestry of brown and clear, and at the area of greatest laminar flow gradient you get complex whirls and even deep vortexes in the water.

Well, it's not precisely like that as it has a lot more to do with the linking of jet exit regions, one to the northern and the other in a more southern stream of flow, with the result being a region that's particularly favored for surface low deeping via outstanding UL divergence.

:lmao::unsure: good stuff

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Kmlwx

Kmlwx

Posted
Posted

Imagine if you will a stream flowing along from west to east. It's a very smoothly flowing stream as the culvert it's in is one of those big wide concrete rivers they have in places like Las Vegas. Now imagine that there's side culverts that can dump into, or along side, the rushing river of rain water. Some jack--- dumps his 20 sewage tankers into one of those side culverts and the ensuing slurry rushes down to meet the swiftly flowing river of crisp clean rain water. The result is a beautiful tapestry of brown and clear, and at the area of greatest laminar flow gradient you get complex whirls and even deep vortexes in the water.

Well, it's not precisely like that as it has a lot more to do with the linking of jet exit regions, one to the northern and the other in a more southern stream of flow, with the result being a region that's particularly favored for surface low deeping via outstanding UL divergence.

laugh.gif Awesome analogy man.

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Ender

Ender

Posted
Posted

...and just one last to the "trend is not my friend" theme. Our, evidently, second best medium range model seems to think the western ridge is going to be a bit less amplified, 100's of meters, than what the EC OP shows:

12zukmet500mbHGHTNA120.gif

UKMET ^

12zeuro500mbHGHTNA120.gif

EC ^

Not to mention the ridge axis is a tad bit further E than I believe the "ideal" position to be for a DC snowstorm. Wes would have to validate that for me, but if I'm right then that favors the more E rather than NNE tracks. It'd certainly favor a track further off the coast that is...

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