Swiss Alps - Biggest Snowfall in 55 Years

Starved of snow the past few years...the Swiss Alps are making up for lost time this month. Up to 120 cm (~4') have been observed during the past ten days...with 62 cm (~2') falling in one 24-hour period in eastern Switzerland (elev. 1,560 m...~5200').

More...

Snowstorm Contest Season

The season starts when the storms start and continues until it/s obvious winter is over. The season runs normally from early December through the middle of March; however, IIRC, the earliest contest storm occurred in late November and the latest storm was in April. Most years there have been ten contest storms.

Not every snowstorm that affects the forecast area will trigger a contest. The criteria used to decide whether a storm is contest-worthy are loosely defined as one that/s expected to:

1. Affect at least six to eight forecast stations and
2. Produce more than a nuisance snowfall (>= 4") and
3. Be well-progged by NWP ~36 to 48 hours before snow is observed at any one station.

Visit the website for more information about how to enter a forecast and how forecasts are verified and scored.

Base Leg...Turning Final - Part II

In addition to the 500 mb time-series of 'MEI-preferred' La Nina years presented in a previous post...these examples also generally depict much different flow regimes than are presently observed...altho '75 is ballpark-ish.

1950...1955...1973...1975
500 mb time-series for early NOV from prior La Nina years.

Will have to look into the winter of '75 / '76 to see how the forecast area was treated.

Bump: Winter '07 / '08 Season-total Snowfall Forecast Contest

Visit NEWxSFC/s web site to enter. Follow the link to 'Enter Season-total Forecast.'

Deadline: 30 November 2007 @ 11:59 PM EST

Details

Base Leg...Turning Final

Climo...2007...1988...1970
Time series of SLP CLIMO...current wx...and 'preferred' MEI-analog Novembers.

First half of NOV 2007 SLPs mimic CLIMO/s low pressure signature over E-PAC. Both 'preferred' MEI-based 'La Nina' analog years are similar but they show a lower correlation with 2007...although '70 leans a bit more toward current conditions at end of period over E-PAC.

Current SLP time-series raises a measure of doubt about this year/s developing consensus for the "warm 'n dry" version of Nina-style winters.

Even stronger evidence of how useless analog forecasting can be...can be seen at 500 mb...


500 mb Climo...2007...1988...1970

Early winter at least...lookin/ more-n-more normal as December approaches.

Heresy in Harrisburg

"...colder than average and snowier than average..."

CBS-affiliate WHP-21/s wx heretic Tom Russell jumps into the winter forecast fray with both boots by taking the contrarian view.

His is the perennial favorite...'cold 'n snowy.' What/s not to like about that?

Bastardi Bold

"...(F)orecaster Joe Bastardi of AccuWeather on Tuesday reiterated his forecast for a warm winter in the Northeast, although the weather has been running colder than normal since Nov. 1. In an interview with MarketWatch, he said it will stay cold until the middle of December and then run about four degrees above normal in the northeastern U.S."

Rather BOLD prediction given December/s temperature departures during past -ENSO events. Much of NE has been one-half to one standard deviation below normal...the same being true for large portions of the M-A.

Nieves de La Nina

Take your pick.



D-J-F snowfall maps for seven La Nina Years Selected by Climate Predition Center using ocean criteria (1942-43...1950-51...1955-56...1970-71...1973-74...1975-76...1988-89)

Make your own.

November/s ENSO Anomaly Forecast

Latest consensus ensemble mean forecast for ENSO Region 3.4 this MET winter (D-J-F) is ~-1.8°C...indicating 'strong' La Nina conditions are expected. Five of the six latest model runs are less than or equal to the forecast ensemble mean. Forecast values have delined each month since May (-0.6°C). Last month/s forecast was -1.6°C.

Winter '07 / '08 - Place Your Bets

Plenty-o-conventional wisdom underfoot this fall about a moderate-to-strong La Nina holding court over the upcoming winter. There/s even more CW obviously based on multi-event composites about how "warm 'n dry" it/s gonna be for the CONUS east of the much 'wetter' Lucky Ducks in OH / TN River valleys.

Too bad there/s no emoticon for skeptical chin-stroking with deep furrowed brow; otherwise...it might go here. Instead...take a look at the long-term composites for temperature and precipitation...

Temperature.................Precipitation

Mean temperature normal to 1°F above normal and mean precipitation '-2" to normal' extreme southern forecast area to 'normal to +2"' elsewhere.

The La Nina Analogs
The current MEI index 'trend match' has its best fit to '70 / '71...although the subsequent winter was almost over before the -ENSO event became strong. The latest numerical and statistical model output forecast a strong event (le -1.5°C) throughout all of met winter.


Note the highly ranked precipitation area (blue) across the GOM states and greater than median values along the EC and interior NE.

The next best MEI matches occurred prior to the non-Nina winters of '78 / 79 and '59 / '60. That leaves '88 / '89 as this winter/s runner-up MEI analog.


The '88 / '89 analog winter is closer to this year/s CW 'La Nina' winter forecast of 'warm and dry.'


Other Indices and MEI -- BFF or What?
PDO - '70 / '71 was 'warm' during its long-term 'cool' phase. This year/s PDO is 'cool' during a 'warm' phase. No benefits from these friends.

QBO...perhaps? The '70 QBO analog is ranked 5th; however...considering its 'E phase' in '70 / '71 flipped to W in March...two months earlier than the expected change in direction this winter. This flip/s timing could well be important this year b/c the QBO/s E phase is a leading indicator for a -AO and its associated increase in EC cold / storminess through the process of downward wave propagation.

AO...NAO...PNA...EP...and other like indices are thought to have skillful forecast ranges of about two weeks. There could be some utility in LR forecasting with these values if a multi-year trend is present.

The '70 / '71 analog demonstrates the variability of La Nina winters and suggests the coming winter won/t wind up 'warm and dry' in the NE or M-A.