White Christmas?

[bzukajo]

I came here to see if any one is predicting a white Christmas for New England, and was very surprised that no one had posted and white Christmas predictions. Did I miss something?......any ways.....any predications for this year?

[gboudx]

Here's a thread:

viewtopic.php?f=22&t=99104

[sphinx]

There is still hope.

The 00 UT ECMWF, 00 UT GEM, and 12 UT GFS are all predicting that a major winter storm will affect the northeastern United States on the 16th and/or 17th of December. While its not unusual to see one model predict something big this far out it is unusual to see three models show a storm this far out.

[Squarethecircle]

Models generally seem to be more accurate in forecasting monsters than weaker storms, but I would say to discard it unless the pattern continues for the next few days; 10 days out means squat in the real world.

[sphinx]

As to how much weight to give a model run:

From today's discussion, which is probably pretty typical, one simulation by an operational model get 5-10% weighting. I suspect the weighting is even smaller when they predict an extreme event; however.

What is the difference between the 06Z GFS ensemble mean and the 06Z GFS super ensemble mean? Do ensemble runs use perturbed initial conditions while superensemble runs use different convective algorithms? Not sure. Of course ensemble means wash out all the interesting stuff! They only tell you wetter or dryer than normal and warmer or colder than normal.

FWIW, I've never seen a 10 day forecast of a storm come close to verifying. I've been watching for quite a few years. On rare occasions 6-8 day storms verify.

THE OFFICIAL 8-14 DAY HEIGHT PROG CONSISTS OF 10 PERCENT OF TODAY'S OPERATIONAL 0Z GFS CENTERED ON DAY 11...5 PERCENT OF TODAY'S OPERATIONAL 6Z GFS CENTERED ON DAY 11...20 PERCENT OF TODAY'S 0Z GFS ENSEMBLE MEAN CENTERED ON DAY 11...25 PERCENT OF TODAY'S 6Z GFS ENSEMBLE MEAN CENTERED ON DAY 11...30 PERCENT OF TODAY'S GFS SUPERENSEMBLE MEAN CENTERED ON DAY 11...AND 10 PERCENT OF TODAY'S CANADIAN ENSEMBLE MEAN CENTERED ON DAY 11.