The pattern

[usedtobe]

There is a chasm between the gfs and euro solutions from last night's runs. The euro really breaks down the pattern quickly putting us in a ridge by 240 hours. You can see on the prog below how different the models are based on their 6-10 day means. Note how different the east pacific and western u.s. look on the two means. Obviously, this pattern is really tough for the models to handle.

The tendency is normally to go with the euro with its higher resolution and overall better performance. However, the euro ensemble mean say not so fast. It does not like the euro solution that puts us in the ridge.

Such a dichotomy between the two solutions will make watching the evolution interesting but also implies that hobbyists and mets should not lock onto any single solution too quickly with regards to individual storms or system evolution.

For kicks, today I again went to the NCEP superensemble D+11 centered mean and looked for how many of the periods dates picked had snow at DCA. The number had jumped from one yesterday to 3 today with the biggest being Dec 5-6 2005. Don't get caught up on the date. Centered mean products only give you and idea of the potential of the pattern if the mean forecast pattern is in the ball park. Last year it tended to be pretty stable. This year, the lack of consistency between runs makes it less useful. Still, it's fun to look at.

[Kmlwx]

Interesting read, Wes. Excellent as always thanks!

[midatlanticweather]

December 5 -6 .... this rings a bell!

Thanks for the info... always good to read!

Jimmy

[CarolineWx]

December 5 -6 .... this rings a bell!

Thanks for the info... always good to read!

Jimmy

Its best not to get caught up on one model run, but the Saturday 12GFS run has a winter storm on December 5th, at this time i think its unlikely, but its fun to look at it.

[usedtobe]

Its best not to get caught up on one model run, but the Saturday 12GFS run has a winter storm on December 5th, at this time i think its unlikely, but its fun to look at it.

With the models all over the place, it wise not to get too excited about a potential storm that's beyond day 10. Still it will be fun watching the pattern.

[CarolineWx]

With the models all over the place, it wise not to get too excited about a potential storm that's beyond day 10. Still it will be fun watching the pattern.

I am expecting the models will be like this all winter, all over the place, but i expect the Pacific will end up winning out, but like i have on my winter outlook, it would not surprise me if we see at least one winter storm in the mid Atlantic area, but its going to be a lot harder than it was last winter.

[Kmlwx]

Yeah, that far out it's like throwing darts randomly.

[RIC Airport]

Thanks for the post, Wes. Its been a bit boring for a while now so at least we have something to keep our interests.

[Wonderdog]

Nice write-up Wes, as usual. Would you surmise that the models are fairly reliable out to day seven at this time provided that they are basically in agreement?

[wxlady]

Interestingly, the latest spaghetti plot is decidedly showing below average 500mb heights over the eastern U.S. For the snow-birds out there, only one run (P007 lower left corner) shows a potential snow event (New England). Lastly, the NAO is looking negative through the end of November, but the latest output shows a trend back up toward the beginning of December.

Spaghetti

GFS Ensembles Surface

NAO Forecast

[Kmlwx]

At this point flurries would be nice for me. I'm not asking for a snowstorm quite yet just for an isolated snow shower or some flurries blowing around.

[MidlothianWX]

Nice read Wes. Thanks for the analysis!

[rainstorm]

http://moe.met.fsu.edu/cgi-bin/gfstc2.cgi?time=2010112206&field=Sea+Level+Pressure&hour=168hr

looks like a bit of a ridge.

[ioke09]

Is there any way to get rid of the -PNA pattern so more cold enters the East? Does increased tropical forcing help or a spike in the AAM?

[Dr No]

Is there any way to get rid of the -PNA pattern so more cold enters the East? Does increased tropical forcing help or a spike in the AAM?

Mass coordination of California households to open their windows?

[Dr No]

Or given the unfavorible angle of the cold, transient blocking, high December sun angle, warm ground, down sloping onto the coastal plain, a rogue sunspot, the decade, or the .1C above normal ocean temps at 56.65 degrees south latitude in the Atlantic, for here.

[rainstorm]

http://moe.met.fsu.edu/cgi-bin/gfstc2.cgi?time=2010112306&field=Sea+Level+Pressure&hour=168hr

hopefully low pressure will continue to trend over greenland.

[Wonderdog]

Or wait for the 12z run to show a lake cutter, instead of a coastal storm shown 12 hours earlier. It's madness to rely on these computer models farther than a week out. And that's probably too far out also.

Or given the unfavorible angle of the cold, transient blocking, high December sun angle, warm ground, down sloping onto the coastal plain, a rogue sunspot, the decade, or the .1C above normal ocean temps at 56.65 degrees south latitude in the Atlantic, for here.

[Analog96]

I am expecting the models will be like this all winter, all over the place, but i expect the Pacific will end up winning out, but like i have on my winter outlook, it would not surprise me if we see at least one winter storm in the mid Atlantic area, but its going to be a lot harder than it was last winter.

I tend to disagree and think the Atlantic will win out, HOWEVER, further South, in your area, the Pacific may very well dominate more.

[Analog96]

Or wait for the 12z run to show a lake cutter, instead of a coastal storm shown 12 hours earlier. It's madness to rely on these computer models farther than a week out. And that's probably too far out also.

It's pretty safe to say those days will be stormy, but anything other than that is speculation.

[usedtobe]

It's pretty safe to say those days will be stormy, but anything other than that is speculation.

True, but I think the pattern still favors storms going to the north and west of DC/Phl thru day 10 and probably even during the GFS Dec 5-6 storm. I don't see a shortwave digging that far south without more of a ridge in the west. Even using the cpc analogs, only 2 of 10 showed a winter storm in that time range, not a ringing endorsement for a possible storm. Before we get a storm in the mid atlantic, I think we need more of a low near Nova Scotia.

[Yeoman]

True, but I think the pattern still favors storms going to the north and west of DC/Phl thru day 10 and probably even during the GFS Dec 5-6 storm. I don't see a shortwave digging that far south without more of a ridge in the west. Even using the cpc analogs, only 2 of 10 showed a winter storm in that time range, not a ringing endorsement for a possible storm. Before we get a storm in the mid atlantic, I think we need more of a low near Nova Scotia.

I'd just like to have something to discuss, even if the chances for a sleet pellet are remote.