Winter '20 / '21 - 22nd Annual 'Regular Season' Snowfall Forecast Contest: FINAL Results

DC (30-JAN-66)

After FOUR snow storm forecasting contests ... under the ‘two-thirds’ rule … forecasters who entered at least THREE forecasts are included in this season's FINAL standings.

Full table with all other error statistics at the Contest/s web site here (direct link).
Individual forecaster's storm statistics here (direct link).

Best Forecasts by Storm (lowest SUMSQ Error Z-Scores)

Top 10 Forecasts (Error statistic:  SUMSQ Z)

 

SUMSQ Error Z is the primary measure of forecaster skill (lower the better).
Accounts for the magnitude and distribution of the storm-total snowfall for all stations.

Top 10 Forecasts (Error statistic:  Total Absolute Error Z - TAE)

 

TAE Error Z is the secondary measure of forecaster skill (lower the better).
Accounts for the magnitude of snowfall forecast errors at each station.

Top 10 Forecasts (Error statistic:  RSQ Z) 

RSQ is a measure of the how well the 'forecast' snowfall captured the variability of the 'observed' snowfall (higher the better).

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28 unique forecasters submitted a total of 2,036 station forecasts.
14 forecasters entered all 4 contests.
5 forecasters entered 3 contests.
8 forecasters entered 1 contest.

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Hope to see y'all again next winter!

Snow chaos in Europe caused by melting sea-ice in the Arctic

"A 50% reduction in Arctic sea-ice cover has increased open-water and winter evaporation to fuel more extreme snowfall further [sic] south across Europe.

"When analyzing the long-term trends from 1979 onwards [sic], researchers found that [sic] for every square meter of winter sea-ice lost from the Barents Sea, there was a corresponding 70 kg increase in the evaporation, moisture, and snow falling over Europe."

Science Daily ... 

Winter '20 / '21 - 20th Annual 'Season-total' Snowfall Forecast Contest: FINAL Results

BOSOX Opening Day
(14-APR-53)

Congratulations to MillVilleWx for issuing the top forecast among forecasters in the 'Season-total' Snowfall Forecast Contest.

Climatology (Period-of-Record-Normal) followed by Consensus verified 1st and 2nd for the first time in the Contest's 20 year history.

Forecasters ranked descending by their Total Absolute Error (TAE)

RED ==> 4th Quartile
WHITE ==>  Interquartile range
BLUE ==> 1st Quartile 

The '%MPRV over PORN' metric indicates how well the forecast improved over climatology.
Skillful forecasts beat climatology.

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Forecasters' stations having the lowest absolute error

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Season-total snowfall from all stations (895") came in 4% below the Period-Of-Record Normal (929").

Winter '20 / '21 ranks 11th among the 17 Contest years since winter '04 / '05 ... the season when BGR and BGM were added to the station list.

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Climo ... Observed ... Departure ... and Percent of Normal Snowfall
...
Forecaster verification table at the Contest web site (direct link)

http://www.newx-forecasts.com/
http://www.newx-forecasts.com/NEWxSFC_22/season-total/season_total_verification_2021.htm

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Teleconnections

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PRIZES
1st place prize (delivered post-paid right to MillVilleWx/s front door):
... pick of the litter from NEWxSFC/s library of meteorology and weather publications
... the august title 'Chief Season-total Snowfall Forecaster' for Winter '21 / '22
... a well-deserved place of honor with past Contest winners

2nd place prize (delivered post-paid right to kc2dux/s front door):
... second pick at NEWxSFC/s library of meteorology and weather publications

3rd place prize (delivered post-paid right to Shillelagh/s front door):
... third pick at NEWxSFC/s library of meteorology and weather publications

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Prizes winners: please contact (newxsfc [at] comcast [dot] net) with a USPS address.

Winter '20 / '21 - 'Season-total' Snowfall Forecast Contest: MAR Totals

VT - Stowe
(Marion Post Wolcott - 1940)

MAR-21 snowfall summary by forecast station.
Rank-ordered descending by percent of monthly period-of-record-normal (%MAR).

Green ==> 4th quartile
White ==> Inter-quartile range
Red ==> 1st quartile

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MAR Forecast Station Highlights
Stations at or above normal monthly snowfall:  none

Biggest Losers
BDR .. MDT ...PHL ... ACY ...BWI ... DCA ... SBY ... RDU (not even a Trace)

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Season-Total-to-Date

MAR P-O-R-N contributes 184" (20%) toward the season-total snowfall (D-J-F-M) of 929"
MAR-21 observed snowfall:  19" (90% below P-O-R-N; 2% of season-total snowfall)
Image courtesy NOHRSC @ http://www.nohrsc.noaa.gov/nsa/

Teleconnections

AO / NAO / PNA data
https://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/daily.index.ascii

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DEC totals
https://newxsfc.blogspot.com/2021/01/winter-20-21-season-total-snowfall.html
JAN totals
https://newxsfc.blogspot.com/2021/02/winter-20-21-season-total-snowfall.html
FEB totals
https://newxsfc.blogspot.com/2021/03/winter-20-21-season-total-snowfall.html

Explosive origins of 'secondary' ice and snow

"... "rime splintering" isn't nearly the whole story.
 
"The new results from the Arctic show ... larger supercooled water droplets, classified as drizzle, play a much more important role in producing secondary ice particles than commonly thought.

" "When an ice particle hits one of those drizzle drops, it triggers freezing, which first forms a solid ice shell around the drop," explained Fan Yang, a co-author on the paper. "Then, as the freezing moves inward, the pressure starts to build because water expands as it freezes. That pressure causes the drizzle drop to shatter, generating more ice particles."

"... drizzle freezing fragmentation can enhance ice particle concentrations in clouds by 10 to 100 times -- and even 1,000 on occasion!"

More ...

 

Winter '20 / '21 - 'Season-total' Snowfall Forecast Contest: FEB Totals

BWI
St. Paul St.looking N from Read St. (MAR-42)

FEB-21 snowfall summary by forecast station.
Rank-ordered descending by percent of monthly period-of-record-normal (%FEB).

Green ==> 4th quartile
White ==> Inter-quartile range
Red ==> 1st quartile

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FEB Forecast Station Highlights
16 stations at or above normal monthly snowfall
ABE
29.7" (400%) above FEB normal
BDR
21.7" (341%) above FEB normal
EWR
21.5" (336%) above FEB normal
NYC
17.1" (292%) above FEB normal
MDT
10.4" (212%) above FEB normal

Biggest Losers
ORF ... RDU (4% and 2% of FEB P-O-R-N)

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Season-Total-to-Date 

FEB P-O-R-N contributes 262" (28%) toward the season-total snowfall (D-J-F-M) of 929"

FEB-21 observed snowfall:  429" (64% above P-O-R-N; 46% of season-total snowfall)

Image courtesy NOHRSC @ http://www.nohrsc.noaa.gov/nsa/

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Teleconnections

AO / NAO / PNA data
https://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/daily.index.ascii

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DEC totals
https://newxsfc.blogspot.com/2021/01/winter-20-21-season-total-snowfall.html
JAN totals
https://newxsfc.blogspot.com/2021/02/winter-20-21-season-total-snowfall.html

Winter '20 / '21 - Snow Storm Contest: Interim Standings #2

 After FOUR contest-worthy snow storms ... under the ‘two-thirds’ rule … forecasters who have entered at least THREE forecasts are included in Interim standings #2.

Complete interim statistics table and chart at the Contest/s web site HERE (direct link)
Forecaster statistics for Winter '20 / '21 contest-worthy snow storms HERE (direct link)

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SUMSQ errors for each contest snow storm are normalized (i.e., standardized) with a 'Z-score' ... then averaged to compute the standings. If a forecaster has issued forecasts for more than two-thirds of all snow storm contests ... then Z-scores from their 'best two-thirds' forecasts are used to calculate the Interim and Final standings.  Similar idea as dropping the lowest test score before computing the final grade.

Winter '20 / '21 - Forecaster Statistics

Lincoln Memorial Reflecting Pool
and Washington Monument (c.1930)

For each contest-worthy snow storm ... the forecasts are verified against the observations of storm-total snowfall.

Statistics are calculated to determine how well each forecast captured the magnitude and distribution of the storm's snowfall.

Individual forecaster statistics for the first four snowstorms here.

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Statistics include:
The average normalized ‘SUMSQ error’ is the Contest/s primary measure of forecaster performance.

This metric measures how well the forecaster/s expected snowfall 'distribution and magnitude' for _all_ forecast stations captured the 'distribution and magnitude' of _all_ observed snowfall amounts.

A forecaster with a lower average SUMSQ Z Score has made more skillful forecasts than a forecaster with higher average SUMSQ Z Score.

Read more »

Winter '20 / '21 - Snow Storm #4: FINAL Results and Storm Summary

Complete forecaster verification table and the FINAL Results / Storm Summary available at NEWxSFC/s home page.

SUMSQ:  sum of square error (")
SUMSQ Z:  Z-score
STP:  storm total precipitation error (")
TAE:  total absolute error (")
AAE:  average absolute error (")
(#):  category rank

Forecast by Observed Snowfall Scatterplots for Top Forecasts
Forecast/s dotted blue line below (above) the Observed snowfall/s solid red line ==> under (over) forecast error.

Station by Station Comparison of Top Forecasters

An Overview of Thundersnow

"The purpose of this article is to summarize our current understanding about this unusual wintertime event.

"This article describes where and when thundersnow happens, the ingredients needed to make thundersnow, and new efforts at understanding and forecasting the occurrence of thundersnow."

http://www.newx-forecasts.com/reference/An%20overview%20of%20thundersnow.PDF