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Roads and trains were shut down across the New York area Monday night and into Tuesday, and for what? It snowed in New York, but only 9.8 inches fell in Central Park after predictions of a foot and a half or more. What went wrong? Forecasters, including yours truly, decided to go all-in on one weather model: the European model (or Euro).

And the Euro was way off. Other models had this storm pegged.1

Update after update, the Euro (produced by the European Center for Medium Range Weather Forecasting) kept predicting very high snow totals in New York. As of Monday morning’s run, the Euro was still projecting a foot and a half in the city. This consistency was too great for forecasters to ignore, especially because the Euro had been the first to jump on events such as the blizzard of 1996 and Hurricane Sandy. It also was one of the first to predict that a March 2001 storm was going to, like this one, be a bust. The Euro had a good track record.

That consistency, though, hid a great sense of uncertainty. The SREF (or Short-Range Ensemble Forecast), produced by the National Weather Service, collects 21 models (shown below). And Sunday night, the SREF indicated that the storm could be very different. Five of the 21 models in the SREF had (on a 10:1 snow-to-liquid ratio) less than 10 inches of snow falling. Nine of the 21 predicted a foot or less. Only eight could have been said to support 18 or more inches of snow in New York City.


In other words, 57 percent of the SREF members Sunday night suggested the forecasts were far too gung-ho. By Monday afternoon, 11 of the 21 members were on the 10-inches-or-less train. Eight of the 21 still supported big-time snow, but they were a minority.

The SREF members were not alone in being suspicious of so much snow. In Sunday’s 7 p.m. run, all of the other major models were against the Euro.

  • The American Global Forecasting System (GFS), which was recently upgraded, had only about 20 millimeters (or 8 inches of snow on a 10-to-1 ratio) falling for the storm. Although the GFS is considered inferior to the Euro by many meteorologists, the difference is probably overrated. Both models perform fairly well over the long term, as was pointed out in The New York Times this week. The GFS was showing the storm would stall too far northeast for New York to get the biggest snows. Instead, as we are seeing, those larger totals would be concentrated over Boston.
  • The GFS solution probably shouldn’t have been ignored given that it was joined by the Canadian’s global model, which had only 25 millimeters (or about 10 inches on a 10-to-1 ratio) falling as snow. The Canadian’s short-range model was slightly more pessimistic than the global. It predicted only about 20 to 25 millimeters (or 8 to 10 inches on a 10-to-1 ratio) of snow.
  • The United Kingdom’s model, which typically rates as the second-most accurate behind the Euro, was also on the little-snow train in New York. It had only 20 millimeters (or 8 inches on a 10-to-1 ratio) falling as snow.
  • Even the United States’ short-range North American Mesocale (NAM) model was on board with smaller accumulations, though it would change its tune in later runs and agree with the Euro for a time. On Sunday night, the NAM went with the 20 millimeters of snow.

Put it all together, and there was plenty of evidence this storm wouldn’t be record-setting in New York. Of course, forecasters are going to miss on occasion. Forecasting weather is very difficult. Models aren’t perfect, and forecasters should be practicing meteorology and not “modelology.”

That said, there are a few lessons to be learned:

  1. I’m not sure forecasters (including amateurs like myself) did a good enough job communicating to the public that there was great uncertainty in the forecast. This has been a problem for media forecasters who have historically been too confident in predicting precipitation events. A study of TV meteorologists in Kansas City found that when they predicted with 100 percent certainty that it would rain, it didn’t one-third of the time. Forecasters typically communicate margin of error by giving a range of outcomes (10 to 12 inches of snow, for example). In this instance, I don’t think the range adequately showed the disagreement among the models. Perhaps a probabilistic forecast is better.
  2. No model is infallible. Forecasters would have been better off averaging all the model data together, even the models that don’t have a stellar record. The Euro is king, but it’s not so good that we should ignore all other forecasts.
  3. There’s nothing wrong with changing a forecast. When the non-Euro models (except for the NAM) stayed consistent in showing about an inch or less of liquid precipitation (or 10 inches of snow on a 10-to-1 ratio) reaching New York and the Euro backed off its biggest predictions Monday afternoon, it was probably time for forecasters to change their stance. They waited too long; I’m not sure why.

Meteorology deals in probabilities and uncertainty. Models, and the forecasters who use those models, aren’t going to be perfect. In this case, there was a big storm. It just so happened to be confined to eastern Long Island and southern New England. But that’ll do little to satisfy New Yorkers who expected a historic blizzard.


Reposted from WUWT

Massive Nor’easter bigger than Hurricane Sandy expected to bring winds, snow, cold blast to Northeast for late March

March came in like a lion, and it looks like the lion isn’t leaving, but you can’t blame the “polar vortex” this time.

As a massive winter storm at sea known as a Nor’easter prepares to skirts the Northeast coast of the USA,  bringing with it high seas and bitterly cold weather in its wake, Dr. Ryan Maue writes:

Massive Nor’easter will develop a warm-core thru a seclusion process.

Compare previous image w/Hurricane Sandy– same 850-mb Wind speed & MSLP. Nor’easter wind field much stronger/larger.

[It is] maybe 4 times more powerful than Sandy based on integrated KE of wind field.

The image of the storm is quite stunning for it’s sheer size. Images and animation follow.



Compare that to these satellite photos of Hurricane Sandy:

Hurricane Sandy satellite image

Hurricane Sandy winding up before making landfall Image: NOAA

Hurricane Sandy near Landfall. Image: NOAA

Watch this animation of the storm as it is forecast to develop, click it to get it to animate full size.


The biggest difference here is the track, Sandy made landfall in NYC, this nor’easter is not expected to there, but will skirt the coast and will make landfall later in Newfoundland,  But, it will have a significant effect on the northeast USA due to its ability to transport air mass.

He adds:

Not the #polarvortex this time. Textbook tropopause fold & baroclinic wrapup


What that will do is act like a pump, and pull bitterly cold air in behind it (note the stream in the rendering above). The result will be a late March like no other, possibly the coldest late March on record for the area:


2012-10-19: The massive cyclonic low churning over Lake Superior, coupled with the jetstream will funnel deep cold arctic air into the central US over the coming week. Fed by Pacific moisture, cold snowy conditions could be on the table for the upper Midwest states. There is enough energy here to channel that frigid arctic air right around to the central eastern states. Brrr!

AWCN11 CWTO 300114
Updated weather summary for all of Southern Ontario and the
National Capital Region issued by Environment Canada
At 8:15 PM EST Tuesday 29 November 2011.

==weather event discussion==

A moisture laden low pressure area that originated over the
southeastern states will move across Eastern Ontario into Southern
Quebec by Wednesday morning. This system brought a large and well
organized area of rain with it. Southwestern Ontario was soaked the
most with rainfall amounts as high as 81.2 mm at Windsor airport.
Freezing rain has appeared as expected over areas east of
Northern Georgian Bay into Algonquin Park.

Below are some unofficial total rain amounts as of 7.00 PM today
unless otherwise noted.

Location rainfall amount (mm)

Windsor 81.2
Harrow 67.7
Sarnia 57.3
Thedford (S Grand Bend) 21.0 (as of 8 AM)
Goderich 31.1
Mount Forest 43.8
Ridgetown 72.2
New Glasgow (se Rodney) 47.0
London 58.8
Tillsonburg 25.6 (as of 8 AM)
Dorchester 24.6 (as of 8 AM)
Delhi 49.5
Waterloo intl airport 53.1
Elora 44.9
Hamilton 44.0
Hamilton botanical gardens 42.3
Grimsby mountain 46.1
Beamsville 35.4 (as of 6 PM)
Port Weller 28.4
Welland 22.4
Toronto Pearson 45.6
Buttonville airport 41.4
Toronto Island 44.9
Toronto city 42.5
Toronto East York 39.4 (as of 6 PM)
Oshawa 39.8
Cobourg 27.7
Peterborough 43.6
Trenton 28.7
Collingwood 38.3
Orillia 39.8 (as of 5 PM)
Barrie 38.1
Muskoka 32.9
Beatrice 24.2
Parry Sound 20.8 (possible freezing rain)
Algonquin Park 34.6 (freezing rain since 5 PM)
Bancroft 39.6
Petawawa 23.0
Pembroke 29.3
Ottawa airport 21.2
Ottawa city 19.9

This weather summary contains preliminary information
And may not constitute an official or final report.


KBUF is down again for a day at least, apparently. This station is developing a fairly poor reliability record….

NOUS61 KBUF 191727
Message Date: Oct 19 2011 17:27:28



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