Christmas Grinch Storm Potential

[buckeye]

Farther it digs south, the further northwest it will end up.

 

more often than not....that is not the case

[Stebo]

It isn't going up the east side of the Appalachian Mountains, not with a long wave trough orientation being north-south like it is with very slow lateral movement to the east.

[buckeye]

also....that marquet discussion is odd.  Wouldn't a more neg tilted trough = a more western solution?

 

As far as depth of the trough.  Ask an eastcoaster their dream scenario....it's a deep trough going negative with a low closing off over or south of TN

[Hoosier]

Farther it digs south, the further northwest it will end up.

 

 

Not if the trough axis is far enough east by that point...that's what I meant.

[OntarioChaser]

Looks like we won't be seeing the 18z GFS or NAM runs today, as they are coming in blacked out on COD.

[Hoosier]

Looks like we won't be seeing the 18z GFS or NAM runs today, as they are coming in blacked out on COD.

 

Looks like the NAM came in on NCEP.

[Stebo]

also....that marquet discussion is odd.  Wouldn't a more neg tilted trough = a more western solution?

 

As far as depth of the trough.  Ask an eastcoaster their dream scenario....it's a deep trough going negative with a low closing off over or south of TN

Yes, but no 500mb low is closing off south of TN on any model except the DGEX and that model is what you look at to see what won't happen.

[Hoosier]

GFS/parallel GFS are coming in on NCEP.

[DAFF]

The track of the storm position is comparable to kids dreaming of Santa's gifts the week before Christmas... There will be winners and the Grinched crew.

 

The weather forecasting tutorial and debate continues.

[OHweather]

A couple of major rubs for an East Coast track...and even some issues for those on the southern fringes of the possible snow (such as southern lower MI, IN, OH, Ontario)...

 

 

 

One issue that has been discussed is the trough taking on a north-south and eventually negative tilt way to the west of the Appalachians. That will force a low pressure system that develops over the south to track more south to north as opposed to SW to NE, which makes even an eventual transfer to the East Coast unlikely as it looks now. The NAO is somewhat negative, but the height anomaly configuration is not good for the East Coast...there are positive height anomalies up the East Coast and into SE Canada. Although there are also positive height anomalies over Greenland with negative height anomalies south of Greenland, the negative height anomalies are too far east to help the East Coast. There's nothing to keep a storm from hooking essentially due north once the trough takes on a negative tilt. The ridging over the West Coast is also too far west for an East Coast low track.

 

One issue for those of us on the southern fringes will be the fairly mild antecedent airmass in place ahead of the storm thanks to a large scale southerly flow between the polar-jet shortwave and associated surface low diving into the Plains Sunday into Monday and high pressure moving off the East Coast. Again, with no negative height anomalies closer to 50N, 50W and hence no confluence over the northeast, this will allow warmth to freely travel northward. There won't be a "cold high" ahead of this storm. This means that those of us south of central WI and MI will have to wait until the Plains system phases with a STJ shortwave rounding the base of the trough Tuesday into Wednesday, which allows a southern surface low to develop, intensify, and eventually pull cold air in. There may be a period of time where the rain/snow line is abnormally far to the west of the low coming out of the south until the cold air can get pulled in.

 

Another issue is the next shortwave already knocking down the ridging on the West Coast as our storm is trying to go to town on Christmas Eve. This shortwave can not come in any faster than currently progged, or else the northern stream energy and trough won't carve out deep enough for anyone south of the upper Great Lakes.

 

So, if you're on the southern fringes, what you want to root for is the West Coast ridging to be a little stronger than progged on the ECM ensemble means, and for the next shortwave to not come in any quicker. This would allow for the northern stream trough to become deeper, and potentially allow for the storm to become stronger and pull in more cold air earlier on and allow for heavier snows to occur farther south. As someone mentioned earlier, the strong nature of the Pac jet associated with the shortwave that will dive into the Plains and carve out our trough in a few days may allow for a slightly deeper trough, and a storm that gets stronger farther south...however, the marginal strength of the West Coast ridging and shortwave getting ready to knock it down give me concern.

 

At this point I'd favor the upper Great Lakes for the heaviest snows in our region...however, a deeper trough would allow for things to work out farther south as well. For those on the eastern fringe, hope the whole evolution is a little more progressive than currently shown but still allows a very deep trough to carve out...which could occur depending on what the West Coast ridging does. Watch the evolution of the West Coast ridging and also the timing of the phase going forward for trends as I'm sure things will still change some from where they are now.

[Stebo]

Excellant points OHweather.

[Hoosier]

Significant changes so far on the 18z GFS.

[Gilbertfly]

Significant changes so far on the 18z GFS.

 

18Z...

 

 

12Z....

[A-L-E-K]

Ugly at 850

[Gilbertfly]

18Z GFS seems to look like the 12Z Canadian at first glance

 

looks like a pretty good thumping for wisco

 

even some snow showers all the way down to nearly Atlanta Christmas eve night......

[Thundersnow12]

Can someone post the link to the PGFS on NCEP on here? Thanks 

[OntarioChaser]

Can someone post the link to the PGFS on NCEP on here? Thanks 

Ya, I'd like to get the NCEP link as well.  I'm having trouble navigating from their homepage and I'm used to using COD, meteocenter, Twisterdata, and e-wall.

[Stebo]

http://mageval.ncep.noaa.gov/model-guidance-model-parameter.php?group=Model%20Guidance&model=gfs&area=namer&cycle=20141219%2018%20UTC&param=200_wnd_ht%2C500_vort_ht%2C1000_500_thick%2C850_temp_ht&fourpan=yes&imagesize=&ps=model#

[Thundersnow12]

http://mageval.ncep.noaa.gov/model-guidance-model-parameter.php?group=Model%20Guidance&model=gfs&area=namer&cycle=20141219%2018%20UTC&param=200_wnd_ht%2C500_vort_ht%2C1000_500_thick%2C850_temp_ht&fourpan=yes&imagesize=&ps=model#

 

Thanks.

 

992mb near/east of SBN at 105hr. Looks like it will be a decent hit here depending on sfc temps 

[OntarioChaser]

http://mageval.ncep.noaa.gov/model-guidance-model-parameter.php?group=Model%20Guidance&model=gfs&area=namer&cycle=20141219%2018%20UTC&param=200_wnd_ht%2C500_vort_ht%2C1000_500_thick%2C850_temp_ht&fourpan=yes&imagesize=&ps=model#

Thanks!

[Thundersnow12]

Precip on the cold side early on across IL fizzles quicker than I would think it would on this run of the PGFS

[Gilbertfly]

Precip on the cold side early on across IL fizzles quicker than I would think it would on this run of the PGFS

 

yeah...pretty stout atlantic feed wrapping in the top....but still the QPF fizzles down this way

[RCNYILWX]

Just a heads up, PGFS won't be running tonight through tomorrow afternoon because of maintenance at NCEP.

Edit: from what we were told by NCEP, I'm assuming the P-GFS outage will start with the 00z run, but if it does run tonight, it definitely won't be running 12z and 18z tomorrow.

[buckeye]

for such an impressively modeled trough this whole thing turns into a hot mess of close calls, flip flops, and wtf's.....hopefully models will come together soon on an impressive hit for someone  other than cabin dwellers and sasquatches.

[Hoosier]

Something I noticed when looking at CIPS analogs for the 12z GFS...the scores are pretty low.  Usually several of these will have a final score above 10.  Notice one of them even has a negative final score yet it still made the list. 

 

 

 

[Stebo]

Something I noticed when looking at CIPS analogs for the 12z GFS...the scores are pretty low.  Usually several of these will have a final score above 10.  Notice one of them even has a negative final score yet it still made the list. 

 

 

 

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Certainly tells me we are in rare air here with this one.

[weatherbo]

Certainly tells me we are in rare air here with this one.

can you explain stebo, I don't understand this.

[Hoosier]

Certainly tells me we are in rare air here with this one.

 

 

FWIW, I clicked around the other sectors valid same time and the scores seemed about what you'd normally see.  Something about the MV sector that threw it I guess. 

[Stebo]

can you explain stebo, I don't understand this.

Well the fact that the CIPS analogs aren't finding anything close to what the GFS is showing means we haven't seen a system too similar to this in the analog time period. I don't know how far back the analog period goes on the CIPS but one listed is 1979. So you are looking at 35 years without a storm too similar to the one forecasted by the GFS. Just taking a stab in the dark my guess is that the analogs go back to 1979, because I think if they went further back the blizzard of 78 would probably be up near the top of the list in similarities, not to say they are the same but there are some similarities.

[A-L-E-K]

yeah, it's an exotic phase, not surprising there aren't many analogs