CONTEST STATUS - Updated: WED ... 01-NOV-17 @ 7:30 PM EDT

Winter '17 / '18 - Snowfall Forecast Contests
19th Annual 'Regular Season'
Season starts when the first flakes start a'flyin'

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17th Annual 'Season-total'
Entries accepted between 01-NOV-17 and 30-NOV-17
Verification period: 01-DEC-17 through 31-MAR-18
Details here

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Winter '16 / '17 - Snowfall Forecast Contests
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18th Annual 'Regular Season'
FINAL results here
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16th Annual 'Season-total'
FINAL results here


Saturday, November 18, 2017

Winter '17 / '18 - Arctic Oscillation Analog Years


 
To date ... 1973 is the leading analog year for the Arctic Oscillation (AO) in the run-up to the coming winter.

The average AO for Winter '17 / '18 would turn out negative should this come to pass.  The analog forecast has winter's AO/s minimum extent in FEB then continues its decline into meteorological spring and suggests a late-winter stratospheric warming event.

One problem.
Winter '73 / '74 ENSO/s signal was strong La Nina (-1.8°C temperature anomaly) yet a weak La Nina appears in the cards for this year and unlike this year ... the corresponding PDO analog year was negative (this year it's positive; trending negative) and QBO was west-positive (this year it's east-negative and trending same).

And herein lies the problem with analogs.
Analog years don't exist in a vacuum.
'08 / '09 weak La Nina; cool PDO trending warmer; QBO west [REJECTED]
'54 / '55 weak La Nina; cool PDO trending cooling; QBO east trending west [REJECTED]
'95 / '96  weak La Nina; warm PDO trending cooler; QBO west trending east
'94 / '95 moderate El Nino; warm trending cooler;  QBO east trending west [REJECTED]

Other teleconnection indexes frequently confound the potential predictive value of a particular index.

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Other correlation-type analysis techniques can also provide insight into the likely state of important winter teleconnection indexes.

Analysis of the Arctic Oscillation (AO) index's period-of-record reveals a statistically significant association (Chi-square Test for Independence; alpha = 0.05) between its sign for the month of NOV and the sign of the average AO index during a subsequent meteorological winter (D-J-F).

Period-of-record correlation analysis finds if NOV/s AO is negative (positive) ... then there's a 72% (52%) probability the winter's average AO/s sign will also be negative (positive).  The analysis false alarm rate is 28% (48%).

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Historical note:  this is NEWxSFC web log's 1000th post!

Thursday, November 16, 2017

Winter '17 / '18 - Outlooks

Thread updated periodically as new outlooks and forecasts are issued from a variety of credible sources.
 
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Judah Cohen (AER) via National Science Foundation
"The combination of cold and wet could result in an above normal snow season for parts of the northern U.S., including the large population centers of the northeastern U.S.
 
"... indicators suggest ... the polar vortex will break down later this winter, potentially unleashing an extended period of severe winter weather." (ED:  not necessarily over the Western Hemisphere)
 
 
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Cohen (AER):  DCA 17"; BOS 64"; all large cities in the NE and M-A above normal
Bastardi (WxBell Analytics):  PHL 30"; DCA near normal
Crawford (Wx Co.):  DCA 17"
Rogers (Commodity Wx Group):  DCA below normal
Tolleris (WxRisk):  DCA near normal
Capital Wx Gang:  DCA 11"; IAD 16"; BWI 16"
Accu-Wx:  I-95 corridor near normal; NYC/BOS >=6" above normal
NECN:  New England near normal 
 

Wednesday, November 15, 2017

Winter '17 / '18 - NOV/s Arctic Oscillation: Winter/s Leading Indicator

The sign of NOV/s Arctic Oscillation (AO) index has a statistically significant (Chi-square Test for Independence; p <= 0.05) association with the sign of the average AO index during meteorological winter (D-J-F).

 AO Contingency Table
 p = 0.046 Nov + Nov - Total
 D-J-F + 16 10 26
 D-J-F - 15 26 41
 Total 31 36 67
 True + 52% 28% False -
 False - 48% 72% True +

'True + (-)' indicates a true (false) prediction.

IOW ... if NOV/s AO is negative ... then there's a 72% chance the winter's average AO/s sign will also be negative ...

...and the association between the AO/s negative sign for NOV and D-J-F has a 28% 'false alarm rate' (FAR).

The relationship is nowhere near as strong when NOV/s AO is positive (48% FAR).

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Interesting ... albeit different ... relationship between NOV/s North Atlantic Oscillation (NAO).

Tuesday, November 7, 2017

Winter '17 / '18 - Eurasia Snow Cover - OCT

12,052,000 km2
18% above 52-year P-O-R-N (10,225,000 km2)

Rank: 11th
Lowest in five years

Eight of the last nine October above period-of-record-normal

Analog years for winter '17 / '18
Rank Winter ENSO
1 06-07 W-
2 69-70 W-
3 77-78 W-
4 00-01 C-
5 98-99 C+

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Data courtesy Rutgers University Global Snow Lab
http://climate.rutgers.edu/snowcover/index.php

Sunday, November 5, 2017

Winter '17 / '18 - Eurasia Snow Cover - OCT - Snow Advance Index (SAI)

OCT-17's snow advance index is negative.
Snow Crow suicide watch now in effect.

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AER reports a statistically significant correlation between their 'winter severity index' and how quickly Eurasian snow cover advances during OCT.

They define the 'winter severity index' by the state of the North Atlantic Oscillation / Arctic Oscillation (N/AO) and interpret it as an indicator of 'high latitude' blocking potential during D-J-F.

More blocking.
More winter.
More better.

Here's the model ...
"When snow cover advances rapidly (slowly) across Eurasia in October, this is an indication that the upcoming winter will be more severe (milder) for the Eastern US [sic], Europe and East Asia.


Study period seems surprisingly short seeing how contiguous monthly Eurasian snow cover data begins in 1970.  How well does the SAI correlate with the N/AO index prior to 1988?

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Snow Advance Index (SAI) backgrounder from AER here.
Earlier Eurasia snow cover posts here.

Wednesday, November 1, 2017

Winter '17 / '18 - 17th Annual 'Season-total' Snowfall Forecast Contest - Call for Forecasts!

NE.Wx/s 17th annual ‘Season-total' Snowfall Forecast Contest is the absolute best ... biggest ... and probably ONLY chance to be recognized for your long-range forecasting acumen ;/

And it's easy.

All you have to do is issue the best forecast for the season-total snowfall at 25 east coast stations from RDU to CAR!

Deadline: THU ... 30-NOV-17 @ 11:59 PM EST

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Visit the Contest's website to enter your forecast.
Follow the link at the top of the page to 'Enter Season-total Forecast.'

1st place prize (delivered post-paid right to your front door):
"The Snow Booklet" by Nolan J. Doesken and Arthur Judson (paperback) and
"Snow in America" by Bernard Mergan (hardcover)

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As always ... NO cost ... NO fees ... NO advertising ... NO annoying requests for personal information to enter the contest.  NEWxSFC is just a fun exercise for winter wx enthusiasts to see who can make the best season-total snowfall forecast.

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Forecast element: sum-total season snowfall @ each station
Forecast period: 01-DEC-17 through 31-MAR-18
Verification: NWS preliminary climate reports (CLM or CF6)

Error statistic: total absolute error [Σ abs(forecast - observed)]
Low score wins.

Update your forecast as often as you want prior to the deadline.
Only your last entry gets verified.

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The reigning NE.Wx ‘Season-Total’ Snowfall Forecasting Champ-een is TQ
Last year's 'Season-total' forecast summary ... verification ... and final results ==> here

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The Contest is open to amateur and professional forecasters; broadcasters with or without trained Seals; any and all weather-biz types and / or wanna-bees; wish-casters ... astrologers ... along with any other universally recognized classes of dreamers; Pollyannas or Cassandras ... registered Nostradamusts ... non-violent megalomaniacs ... woolly-bear caterpillars or their agents ... pest detectives ... NE.Wx NG veterans and lurkers; refugees from AmericanWx ... USWeather survivors ... including self-imposed exiles from Eastern Wx ... and of course ... meteorologists.

In honor of USENET/s ne.weather/s patron saint Mr. Joseph Bartlo's final request (RIP) ... trolls ... goats ... hat3-lsiters ... and psests need not apply.