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'

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

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

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%).

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.
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)
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).

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+

Data courtesy Rutgers University Global Snow Lab

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.

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?

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

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)

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.

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.

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

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 patron saint Mr. Joseph Bartlo's final request (RIP) ... trolls ... goats ... hat3-lsiters ... and psests need not apply.

Sunday, October 29, 2017

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

Winter '17 / '18 - Correlation of Eurasia's OCT Snow Cover and Season-total Snowfall in NE and M-A Regions 

Winter '17 / '18 - First Contact

Post-frontal ... elevation snows INVOF UVM associated with SFC LOWs

Boone ... NC (3146' MSL)
KTNB 291615Z AUTO 30013G25KT 4SM -SN SCT008 BKN014 BKN020 02/01

Richlands ... VA (2653' MSL)
KJFZ 291555Z AUTO 32004KT 3SM -SN SCT004 BKN007 OVC014 00/00 A2972 RMK AO2 T00011001

Wise county ... VA (2684' MSL)
KLNP 291555Z AUTO 31004KT 1 1/2SM -SN OVC003 00/00

Hot Springs ... VA (3793' MSL)
KHSP 291555Z AUTO 29014KT M1/4SM -SN OVC003 02/02

Bluefield ... WV (2856' MSL)
KBLF 291552Z AUTO 31008KT 1 3/4SM -SN BR BKN006 OVC012 00/M01

Bedford county ... PA (1161' MSL)
KHMZ 291555Z AUTO 32006KT 5SM -SN OVC010 07/06

Thursday, October 26, 2017

Saturday, October 7, 2017

Winter '17 / '18 - Correlation of Eurasia's OCT Snow Cover and Season-total Snowfall in NE and M-A Regions

The correlation between the areal coverage of Eurasia/s OCT snow cover and season-total snowfall has become broad-brushed conventional wisdom (CW) following the innovative research by AER climatologist Dr. Judah Cohen.

But ... just how well does the CW hold up for NEWxSFC/s forecast stations across New England (NE) and the mid-Atlantic (M-A) regions?

To find out ... monthly period-of-record areal snow cover data for Eurasia from Rutgers Global Snow Lab were correlated with season-total snowfall data for 27 of NEWxSFC/s stations.

A positive and statistically significant correlation means the greater the areal snow cover over Eurasia in OCT ... the greater the season-total snowfall for the following winter.

An Excel radar chart shown below depicts the results of the analysis.

DISCUSSION:  Stations between the inner and outer rings have a positive correlation coefficient statistically different than zero.  The coefficients range between 0.289 (CAR) and 0.424 (ORH).   Correlation values in this range are classified generally as 'low' (moderate:  >= 0.5 - 0.7; strong:  >= 0.7 - 0.9).  Even though the correlations are weak ... they can still provide useful information for seasonal snowfall forecasts.

The analysis also showed other significant correlations of interest.
- RIC/s season-total snowfall had a positive correlation with Eurasia/s AUG areal snow cover.
Eurasia/s AUG-17 snow over was well below normal ==> lower season-total snowfall @RIC this winter.

- NYC/s season-total snowfall had a negative correlation with Eurasia's JUN areal snow cover.
Eurasia/s JUN-17 snow cover was above normal ==> lower season-total snowfall @NYC this winter.

There may be other interesting artifacts lurking in the data when the full analysis is completed.

FINDINGS:  data analysis supports the CW for NE forecast stations but not so much across the M-A.

Controls for ENSO state and / or other teleconnection indices ... such as AO ... NAO ... MEI ... PDO ... etc. have not been applied.