12/23/2010 - 12/24/2010 Midwest storm

[Jeff Duda]

The long range models are picking up on a storm set to fly east across the center of the country on the 23rd and 24th. This could be a Christmas Eve storm for those east of the Mississippi, but the GFS, ECMWF, and GEM are not in agreement on timing. The 12Z GFS this morning accelerated the storm and tightened it up a bit from the 00Z run. The ECMWF and GEM are slower, not bringing most of the system past (at least my area...IA) until early on the 24th as opposed to late on the 23rd. This is a pacific system, so it is sure to have more moisture with it. It also resembles the same system that unofficially started winter in IA last year, remaining an open wave through a good portion of its travel across the CONUS. There don't appear to be any arctic outbreaks to clear the eastern half of the country between now and then, so the stage may be set for a big snow event across portions of the Midwest and Great Lakes regions as well as the mid-Atlantic.

 

[Robert Dewey]

I'm not convinced on a track yet, with the new 12/19 0z Euro trending further north, and a pretty solid spread among the 0z ensembles. In fact, the operational 6z GFS is the furthest south in the track envelope: http://www.emc.ncep.noaa.gov/gmb/tp...rack.aeperts.2010121906.east_coast.single.gif

If the storm ends up being stronger, I'd anticipate a further north track, which I'm certainly not opposed to

 

[Chris Carter]

Dewey, maybe you can help me out here, i'm looking at the 0z Euro model on the psu website. The system is taking a southern track from the panhandle of TX/OK to Tenn.

http://www.meteo.psu.edu/~gadomski/ECMWF_0z/ecmwfloop.html

Timing is still an issue with the Euro being slower and stronger and the GFS being faster and weaker. But with 120 hours away, still a lot of room for the models to flip back and forth.

 

[Robert Dewey]

Dewey, maybe you can help me out here, i'm looking at the 0z Euro model on the psu website. The system is taking a southern track from the panhandle of TX/OK to Tenn.

http://www.meteo.psu.edu/~gadomski/ECMWF_0z/ecmwfloop.html

Timing is still an issue with the Euro being slower and stronger and the GFS being faster and weaker. But with 120 hours away, still a lot of room for the models to flip back and forth.

The trend is between yesterday's 12z and last night's 0z. The low went from NW MS on the 12z, to central TN on the 0z, and now up toward KY on today's 12z. You're talking 150 miles over the course of 24 hours... While not as big of a jump as we saw with the 12/12, it's still important.

It should be noted that today's 12z Euro is in excellent agreement with the 12z GFS and the Canadian.

But, what concerns me is that the operational models are still on the south side of the ensemble envelope - http://www.emc.ncep.noaa.gov/gmb/tp...rack.aeperts.2010121912.east_coast.single.gif

Again, the spread isn't extreme, but for anyone along the low track it could definitely make-or-break your snow potential.

 

[Jeff Duda]

I've noticed the GFS is slowing the system down to better match the timing of the ECMWF and GEM models today. It looks to be more of a 24th event now for most of those who will be affected.

 

[DWest]

Looks like the potential for a major ice storm for my region of south central Missouri...right in time for Christmas. Admittedly I'm not any good with making my own forecasts, and have been reading the area forecast discussion; St. Louis office is pointing out that even the more conservative models placing at least 1/3" of the QPF into the freezing rain column. As much as I like wintry precipitation, not so big on ice given the high probability of service outages.

MODELS HAVE ALSO
COME IN LINE A BIT BETTER ON TIMING...PREFERRING TO HOLD OFF ON THE
FASTER TRENDS THAT WERE CHARACTERISING THE MORE RECENT RUNS...AND
INSTEAD SIDE WITH AN INITIAL ONSET THURS AFTN FOR THE WRN FA WITH AN
IMPACT FOR MUCH OF THE FA THEN ON THURS NGT INTO CHRISTMAS EVE
MORNING. MODEL QPF ALL SEEMS TO POINT TOWARDS AT LEAST A THIRD OF AN
INCH OF LIQUID TO CONVERT TO ICE...WITH THE ECMWF AND GFS SUGGESTING
MUCH MORE. MODELS THEN SUGGEST A TENTH OF A QUARTER INCH OF LIQUID
CONVERTED TO SNOW WILL THEN OCCUR AT THE END WITH SOME SLEET MIXED
IN AS WELL.

 

[Chris Carter]

I don't know what to say.

The models now have the track so far south its outrageous. Its pretty much into the TX/OK panhandle then along the gulf coast and then rides NE as a classic Nor' Easter for the holidays. Both the 12z GFS and EC confirm this.

 

[Jesse Risley]

I don't know what to say.

The models now have the track so far south its outrageous. Its pretty much into the TX/OK panhandle then along the gulf coast and then rides NE as a classic Nor' Easter for the holidays. Both the 12z GFS and EC confirm this.

I suspect that we'll continue to see run to run changes in the models until the system is adequately sampled by the network of upper-air observations, which looks to be another 36-48 hours away.

Right now, if I were to take a guess, some sort of a solution between the GFS/NAM/GEM would probably be prudent, though timing and track differences have yet to be resolved.

Speaking just based on anecdotal observations, the late period medium into the long-range model outputs tend to start off with a more southerly placement of these systems, and then as the event draws closer the models slowly bring the systems back more northward. If that's going to happen, the rough extent as to what, if any, northward track the system is going to take should be a bit clearer by 12z THUR.

 

[DWest]

The southern track is a double edged sword; takes many areas out of the ice zone but at the same time it's absolutely killed the QPF for my area. The GFS was at one point looking at around an inch of liquid equivalent, which then trended progressively less with each subsequent run...0.9",0.6", 0.5", 0.4", now even slightly less than that. Still have hope that this storm picks up on the more northerly track as Jesse alluded to. If it doesn't, this thing may turn out to be somewhat disappointing in terms of total accumulations, even if the liquid to snow ratio is somewhat higher deeper in the cold sector.

 

[Jesse Risley]

The southern track is a double edged sword; takes many areas out of the ice zone but at the same time it's absolutely killed the QPF for my area. The GFS was at one point looking at around an inch of liquid equivalent, which then trended progressively less with each subsequent run...0.9",0.6", 0.5", 0.4", now even slightly less than that. Still have hope that this storm picks up on the more northerly track as Jesse alluded to. If it doesn't, this thing may turn out to be somewhat disappointing in terms of total accumulations, even if the liquid to snow ratio is somewhat higher deeper in the cold sector.

Given a look at the forecast upper-level pattern for FRI-SAT, it would appear that the southern impulse will be shunted further south than the models were showing a few days ago.

If you look at the position of the upper-level features across the eastern CONUS, coupled with the ridge in place over the southern Continental Divide region, it would appear that the southern phase of energy will take some sort of a more southerly track (than shown 48-72 hours ago on the GFS), though it may or may not be immediately proximal to the Gulf Coast.

 

[Chris Carter]

Most of the models i have seen, really drain the moisture out of this system and don't even develop a low pressure at all once it comes out of the southwest. It doesn't even turn into an actually system until its close to FL and veers wide right of the east coast, just like the last storm.

We'll get our few inches of snow here, but this could have been a lot better with more gulf moisture feeding into this thing.

 

[Jeff House]

I look for a good swath of snow right under the 700mb low from eastern Nebraska into Iowa. Being north of the surface trough (not really a low) but south of the 700/850 will be a real bummer for Christmas in much of Kansas and western Missouri. Freezing drizzle or plain drizzle anyone? I used to live in Wichita and saw that way too much for this snow fan. I have doubts even for Kansas City getting snow. Without splitting hairs on things like 850 temps, and which PVA lobe will dominate, basic pattern recongition points to disappointment in Kansas with the 700/850 lows north.

I would issue the same caution points for those from Missouri into the Tennessee Valley. The 700/850 low is tracking north over Kentucky. Will not comment beyond that, because anything can happen on the East Coast with lows phasing and redeveloping.

Merry Christmas y'all!

 

[Chris Carter]

Sleet pellets have started to fall near Offutt AFB south of Omaha, very isolated, but atleast we know its making it to the ground unlike earlier this morning.

 

[DWest]

Current total snowfall at my locale is a solid 2.5", with light graupel falling and a temperature of 33F. That completely blows away the 4AM snowfall graphic (1.4"). They've updated it now to put parts of my county at warning criteria snowfall totals, with the majority hanging around 5.7"...I won't hold my breath, but I can always hope.

 

[Chris Carter]

We probably got under an inch as even the grass is still showing in the yard. Not a white Christmas in my book.