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December 26-27 Winter Storm Part 2


Hoosier

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So recapping the last 3-4 days of model runs for here. First its too far SE to see any snow, then its good, then too NW for comfort, and now trending SE again. Im certainly safe for now...but trends arent in the favor of SE MI...but now that its been sampled, I have to believe the chances of this being a complete miss are extremely low. Also note how much slower than NAM is...the latest run has snow starting here around 2pm Wed and lasting through something like 8am Thur. Previous runs were more like 7am Wed to 3am Thu. As long as we get a nice blanket of snow I will be happy. Its also looking increasingly likely that it will be my favorite kind of snow, powder. If we miss the jackpot...no big deal. If the NAM clown maps dont verify...again, if anyone hoped they would...THATS the problem. But if I get NO snow from this...I will be EXTREMELY pissed off.

Your last sentence is how I feel. I think you guys will get some decent snow. Your far enough east that you seem to get at least some snow from these systems. Enjoy!

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I'm pretty confident this will be a EVV to CLE/CMH special. I'll have to live with my 2-4" walloping.

The crux of our problem is the flow's too progressive...

1. The shortwave behind this system is hauling serious ass.

Compare the look at 500mb on the 06z NAM Sunday versus the 12z NAM today. Note how on the 06z Sunday run of the NAM the shortwave behind this system was still well off the west coast (arrow). As a result, there was enough room in between the two system to develop at least a modest ridge (red circle) along the west coast, which helped our trough dig further and caused more interaction with the northern stream wave (the red x). Fast forward a day of runs later, and the system is sitting over the west coast states (easily hundreds of miles inland) The cause of this is our long time friend the raging Pacific Jet. So even if, theoretically, there was less blocking/confluence over SE Canada (I'll get to that in point 2), the system probably still wouldn't get too much further north with the lack of connection the northern stream wave.

06z Sunday NAM

post-206-0-60360600-1356361552_thumb.png

12z Monday NAM

post-206-0-99052900-1356361713_thumb.png

2. The shortwave ahead of this system is pure crap.

The Christmas Miracle event (more like the Christmas lump of coal) has, if anything, trended weaker over the last 1-2 days. Recall back late last week, all of the models at one point were showing a pretty potent shortwave with a quick hitting 2-4" of snowfall. The stronger wave was enoguh to shove the confluence NE, and thus helped the SE ridge ahead of this system to really amplify, which also helped the trough to dig more. Now, since this wave has trended weaker, it is struggling to completely get rid of the confluent flow in SE Canada which prevents the SE ridge from getting as amped. So instead of a storm cutting NNE to Cleveland/Toledo like the 06z NAM showed, we get a storm that more or less tracks NE from Memphis to OH/KY/WV and then it transfers to the east coast.

Note the flatter heights across the Ohio Valley on the 12z Monday NAM versus the 06z Sunday NAM. While not significant in the general sense that this will be a big storm, it is enough to rule out any chance at a NW trend, and more likely a SE adjustment.

06z Sunday NAM

post-206-0-93736600-1356363606_thumb.png

12z Monday NAM

nam_namer_018_500_vort_ht_s.gif

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I'm pretty confident this will be a EVV to CLE/CMH special. I'll have to live with my 2-4" walloping.

The crux of our problem is the flow's too progressive...

1. The shortwave behind this system is hauling serious ass.

Compare the look at 500mb on the 06z NAM Sunday versus the 12z NAM today. Note how on the 06z Sunday run of the NAM the shortwave behind this system was still well off the west coast (arrow). As a result, there was enough room in between the two system to develop at least a modest ridge (red circle) along the west coast, which helped our trough dig further and caused more interaction with the northern stream wave (the red x). Fast forward a day of runs later, and the system is sitting over the west coast states (easily hundreds of miles inland) The cause of this is our long time friend the raging Pacific Jet. So even if, theoretically, there was less blocking/confluence over SE Canada (I'll get to that in point 2), the system probably still wouldn't get too much further north with the lack of connection the northern stream wave.

06z Sunday NAM

post-206-0-60360600-1356361552_thumb.png

12z Monday NAM

post-206-0-99052900-1356361713_thumb.png

2. The shortwave ahead of this system is pure crap.

The Christmas Miracle event (more like the Christmas lump of coal) has, if anything, trended weaker over the last 1-2 days. Recall back late last week, all of the models at one point were showing a pretty potent shortwave with a quick hitting 2-4" of snowfall. The stronger wave was enoguh to shove the confluence NE, and thus helped the SE ridge ahead of this system to really amplify, which also helped the trough to dig more. Now, since this wave has trended weaker, it is struggling to completely get rid of the confluent flow in SE Canada which prevents the SE ridge from getting as amped. So instead of a storm cutting NNE to Cleveland/Toledo like the 06z NAM showed, we get a storm that more or less tracks NE from Memphis to OH/KY/WV and then it transfers to the east coast.

Note the flatter heights across the Ohio Valley on the 12z Monday NAM versus the 06z Sunday NAM. While not significant in the general sense that this will be a big storm, it is enough to rule out any chance at a NW trend, and more likely a SE adjustment.

06z Sunday NAM

post-206-0-93736600-1356363606_thumb.png

12z Monday NAM

nam_namer_018_500_vort_ht_s.gif

Nice analysis Powerball. And excellent point about the kicker off the WC. I hadn't noticed that but I agree, that's probably playing a big factor in why the models are demurring from their earlier solutions.

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As weak as it is (in comparison to the NAM), the GFS qpf line of 0.25"+ has actually expanded further NW in lower MI compared to the 6z run. My gut feeling right now is that both a major snowstorm or a complete miss are extremely unlikely scenarios.

The decreasing qpf is discouraging, but remember...this is NOT a wet snow folks. Ratios could still make this a very nice event. Stay tuned.

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That last NAM run was like reading Penthouse Forum. You know it's not going to happen to you (~2+"/hr snow rates for 4 hours at MIE), but it's fun to fantasize about.

Seriously, though, is there a significant danger of a warm nose cutting into snowfall totals out this way? I've seen a couple bufkits that hint at temps being close aloft, especially with some of the NAM runs. Thanks.

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You defiantly have to take that in consideration but also could yield higher snow ratios at the same time maybe 13/14 to 1?

That's not quite how it works.

While surface temps may be cooler, at the same time the gist of what decides one's snowfall ratios is how/where the snowflakes form aloft.

If lift is above/below the DGZ, or if moisture is lacking in the DGZ, you can still get pretty sucky low ratios.

We saw this with the GHD 2011 storm.

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there was less blocking/confluence over SE Canada (I'll get to that in point 2), the system probably still wouldn't get too much further north with the lack of connection the northern stream wave.

...

Good point...for those of us on the southeast flanks, I was hoping to see this become more closed off earlier and earlier. And over the last several runs, it started to do just that. Like you said, without as much of a northern stream connection, the storm will roll more east than north.

I won't rule out a nw trend back...more likely would be a stronger system that would throw more precip and warmth nw. Like I said, I'm not use to seeing a se trend like this...very strange so I'm naturally skeptical.

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12z GGEM barely grazes LAF. Things haven't trended in our direction so far today...for getting bigger totals. Still should get something, assuming things don't really get screwy. Taking it all into consideration...first call for a few Indiana sites. Might be conservative, but no time to shoot from the hip. We'll revise later.

LAF: 2-5"

OKK: 3-6"

IND: 5-8"

MIE: 5-8"

FWA: 3-6"

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Initial low to medium confidence call for LAF is 7-10". May not surpass the 12/15/07 event in terms of totals but factoring in the wind could make it the most impressive storm since VD 2007.

The NAM qpf could very well be overdone...however, given the system origin and strong low level flow off the Gulf into this system, I wouldn't be surprised to see the GFS trend wetter.

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12z GGEM barely grazes LAF. Things haven't trended in our direction so far today...for getting bigger totals. Still should get something, assuming things don't really get screwy. Taking it all into consideration...first call for a few Indiana sites. Might be conservative, but no time to shoot from the hip. We'll revise later.

LAF: 2-5"

OKK: 3-6"

IND: 5-8"

MIE: 5-8"

FWA: 3-6"

There's a pretty clear discrepancy between the RGEM and GGEM with the track of the surface low... if you flip between 48hrs and 49hrs the low shifts directly east from there.

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I'm starting to dig OB's 2-4 call.

Yeah, I don't know. It's just a gut feeling. It's just that, with the exception of 2007-2008 and the first half of 2008-2009, it has been the northeast US which has been seeing the most snow in recent big winters.

I'm still thinking 4" maximum, with those closer to the lake getting more due to the southerly track of the storm. I think north Toronto and Markham should get about 2 or 3".

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There's a pretty clear discrepancy between the RGEM and GGEM with the track of the surface low... if you flip between 48hrs and 49hrs the low shifts directly east from there.

Yeah, I saw that. Not sure if the RGEM would come a little farther north, after 48, but looks like it might have..if it went that far.

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12z GGEM barely grazes LAF. Things haven't trended in our direction so far today...for getting bigger totals. Still should get something, assuming things don't really get screwy. Taking it all into consideration...first call for a few Indiana sites. Might be conservative, but no time to shoot from the hip. We'll revise later.

LAF: 2-5"

OKK: 3-6"

IND: 5-8"

MIE: 5-8"

FWA: 3-6"

Initial low to medium confidence call for LAF is 7-10". May not surpass the 12/15/07 event in terms of totals but factoring in the wind could make it the most impressive storm since VD 2007.

The NAM qpf could very well be overdone...however, given the system origin and strong low level flow off the Gulf into this system, I wouldn't be surprised to see the GFS trend wetter.

6" for LAF - Lock it.

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Guidance probably shifted a bit with the 12z batch as the storm is finally getting better sampled. I'd wait till the 00z runs are in before calling for specific amounts. I think by then we'll know if the shift southeast was legit, or if it was a temporary bump. With the last storm there were changes right up until the day it happened.

The difference in amounts over Oklahoma is pretty astounding between the varying models run to run. Some models have buried OK with over 20" of snow. Last night's Euro and this morning's GFS have WAAAY less snow in that area.

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Izzi threw in a little LAF tidbit in LOT's overnight AFD. Crappy snow growth and warm temps FTL.

BUFKIT

FORECAST SOUNDINGS FROM KLAF SUGGEST THAT THIS SYSTEM MAY NOT BE THE

MOST EFFICIENT SNOW PRODUCER WITH DEEP ISOTHERMAL LAYER AROUND -5C

FROM THE SURFACE TO OVER 700MB AND A FAIRLY SHALLOW FAVORABLE

DENDRITIC GROWTH LAYER. IN ADDITION...T/H CROSS SECTIONS SHOW STRONG

OMEGA WILL BE ABOVE THE MOST FAVORED SNOW GROWTH REGION.

FINALLY...SURFACE TEMPS ALSO LOOK MARGINAL AND POSSIBLY FLIRTING

WITH 32F OR JUST ABOVE OUTSIDE OF THE HEAVIER PRECIP WHICH WILL ALSO

TEND TO LIMIT ACCUMS AND BLOW-ABILITY OF THE SNOW. BASED ON CURRENT

FORECAST TRACK AND WHAT COULD BE A BIT GENEROUS 10:1 SLR USING A

CONSENSUS QPF VALUE THERE STILL LOOKS TO BE THE POTENTIAL FOR

COUPLE/FEW INCHES OF SNOW OVER FAR SE CWA WITH AMOUNTS QUICKLY

TAPERING OFF TO THE NORTHWEST.

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