Saturday, June 25, 2022

Winter '22 / '23 - Snowmageddon Weather in North America More Influenced by Tropics Than Arctic

"Winter weather patterns in North America are dictated by changes to the polar vortex winds high in the atmosphere, but the most significant cold snaps are more likely influenced by the tropics ..."

"The study, published in Geophysical Research Letters on December 27, 2019, also revealed that, unlike in Europe, the most extreme cold snaps affecting the whole of North America are not most likely to occur after a weak (polar) vortex. Instead, the shape of the vortex and conditions in the tropics were identified as stronger influences of these conditions"

More ...

Sunday, April 17, 2022

Winter '21 / '22 - 23nd Annual 'Regular Season' Snowfall Forecast Contest: FINAL Results

VT
After FIVE contest-worthy snow storms ... under the ‘two-thirds’ rule … forecasters who entered at least FOUR 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).


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

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Top 10 Forecasts - All Storms (Error statistic:  Sum of Squared Errors Z - 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.

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Top 10 Forecasts - All Storms (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.

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Top 10 Forecasts - All Storms (Error statistic:  R-squared Z - 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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Forecaster's Skill Score (Forecaster Z-score - NWS ER WFOs Z-score) / ER NWS WFOs Z-Score

Skill score measures forecaster performance against a standard (NWS ER WFOs).  Positive (negative) values indicate better (worse) performance compared to the standard.  0% for NWS does not indicate 'no skill.'

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19 unique forecasters submitted a total of 1,623 station forecasts.
6 forecasters entered all 5 contests.
4 forecasters entered 4 contests.
5 forecasters entered 3 contests.
1 forecasters entered 2 contests.
3 forecasters entered 1 contest.

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Hope to see y'all again next winter!

Wednesday, April 13, 2022

Winter '21 / '22 - 21st Annual 'Season-total' Snowfall Forecast Contest: FINAL Results

ACY
01-FEB-28

Congratulations to Any.Wx for issuing the best season-total snowfall forecast for Winter '21 / '22.

Complete forecaster verification table at the Contest web site.
http://www.newx-forecasts.com/NEWxSFC_23/season-total/season_total_verification_2122.htm

Forecasters ranked ascending by their Total Absolute Error (TAE).

BLUE ==> 1st Quartile
WHITE ==>  Interquartile range
RED ==> 4th Quartile
ORANGE:  Winter '21 / '22 Chief 'Season-total' Forecaster (winner of  '20 / '21 contest)

The '%MPRV over PORN' metric indicates how much the forecast was an improvement over Period-Of-Record-Normal (PORN).  Skillful forecasts beat PORN.

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Forecasters' stations having the lowest absolute error.

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Winter '21 / '22 ranks 12th among the 18 Contest seasons since Winter '04 / '05 ... the winter when BGR and BGM were added to the station list.

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Season-total snowfall for Winter '21 / 22 for all forecast stations (818") came in 12% below the Period-Of-Record Normal (925").

Station Climo ... Observed Snowfall ... Departure from Normal ... and Percent of Normal Snowfall

DEC snowfall totals:
https://newxsfc.blogspot.com/2022/01/winter-21-22-season-total-snowfall.html

JAN snowfall totals:
https://newxsfc.blogspot.com/2022/02/winter-21-22-season-total-snowfall.html

FEB snowfall totals:
https://newxsfc.blogspot.com/2022/03/winter-21-22-season-total-snowfall.html

MAR snowfall totals:
https://newxsfc.blogspot.com/2022/04/winter-21-22-season-total-snowfall.html

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Season-total snowfall analysis courtesy NOHRSC

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Teleconnections


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PRIZES
1st place prize (delivered post-paid right to Any.Wx/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 '22 / '23
... a well-deserved place of honor with past Contest winners

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

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

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

Friday, April 8, 2022

Winter '21 / '22 - 'Season-total' Snowfall Forecast Contest: MAR Snowfall Totals

Flat Iron Building ... NYC (1905)

MAR-22 snowfall summary by forecast station.

Rank ordered descending by percent of monthly period-of-record-normal (P-O-R-N). 

Green ==> 4th quartile
White ==> less than 4h and greater than 1st quartile (inter-quartile range)
Red ==> 1st quartile

Obs reported as 0.05" denote a Trace amount (observed but not measurable)

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MAR Forecast Station Highlights
2 stations at or above normal monthly snowfall.

Biggest Losers
15 stations with less then half their monthly normal snowfall.
ACY ... ORF ... RDU snow observed but not measured (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 925".
MAR-22 observed snowfall:  117" (64% of monthly P-O-R-N; 13% of season-total snowfall)

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

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Teleconnections

 


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DEC snowfall totals:
https://newxsfc.blogspot.com/2022/01/winter-21-22-season-total-snowfall.html

JAN snowfall totals:
https://newxsfc.blogspot.com/2022/02/winter-21-22-season-total-snowfall.html

FEB snowfall totals:
https://newxsfc.blogspot.com/2022/03/winter-21-22-season-total-snowfall.html

Thursday, March 10, 2022

Contest Status

Winter '21 / '22 - Snowfall Forecast Contests
23rd Annual 'Snow Storm' Snowfall Forecast Contest

Interim Standings here

Snow Storm #6
Synoptiscope in VCP32

Snow Storm #5 - (25/26-FEB-22)
FINAL Results and Storm Summary here

Wednesday, March 9, 2022

Winter '21 / '22 - 'Season-total' Snowfall Forecast Contest: FEB Snowfall Totals

Somerset County ... PA-Turnpike (c.1940)

FEB-22 snowfall summary by forecast station.

Rank ordered descending by percent of monthly period-of-record-normal (P-O-R-N).

Green ==> 4th quartile
White ==> less than 4h and greater than 1st quartile (inter-quartile range)
Red ==> 1st quartile

Obs reported as 0.05" denote a Trace (observed but not measurable)

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FEB Forecast Station Highlights
5 stations at or above normal monthly snowfall.

Biggest Losers
12 stations with less then half their monthly normal snowfall.
DCA ... RIC ... and ORF snow observed but not measured (trace)
RDU got skunked.

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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-22 observed snowfall:  185" (71% of monthly P-O-R-N; 20% of season-total snowfall)

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

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Teleconnections

AO / NAO / PNA data

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DEC snowfall totals:
https://newxsfc.blogspot.com/2022/01/winter-21-22-season-total-snowfall.html

JAN snowfall totals:
https://newxsfc.blogspot.com/2022/02/winter-21-22-season-total-snowfall.html

Friday, March 4, 2022

Winter '21 / '22 - Regular Season: Interim Standings #3

New Hartford ... CT
14-Feb-1899

After 5 contest-worthy snow storms ... under the ‘two-thirds’ rule  … forecasters who have entered at least 4 forecasts are included in Interim Standings #3.

Complete interim statistics table and chart at the Contest/s web site (direct link)
Forecaster statistics for Winter '21 / '22 contest snow storms (direct link)

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SUMSQ errors for each contest snow storm are normalized (i.e., standardized) with a 'Z-score' ... then averaged and ranked 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.

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Interim Standings #1
https://newxsfc.blogspot.com/2022/02/winter-21-22-regular-season-interim.html

Interim Standings #2
https://newxsfc.blogspot.com/2022/02/winter-21-22-regular-season-interim2.html

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NOTE:  MitchelVolk's 'Previous Rank(s)' should read '2,2 '

Sunday, February 27, 2022

Winter '21 / '22 - Snow Storm #5: 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

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Forecast by Observed Snowfall Scatterplots for Top 4 Forecasts
Forecast/s dotted blue line below (above) the Observed snowfall/s solid red line ==> under (over) forecast bias.

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Comparison of Top 4 Forecasts and Observed Snowfall by Station

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Forecast Skill Score measured against NWS ER WFOs
Positive skill values indicate a forecast/s improvement over the NWS forecasts.
Bias is the arithmetic difference between the average Forecast snowfall and the average Observed snowfall.

Saturday, February 26, 2022

Winter '21 / '22 - Snow Storm #5: Preliminary STP Verification

Preliminary verification of storm-total snowfalls for FRI and SAT from CDUS41 (CLI) ... CXUS51 (CF6) ... METARs ... and PNS bulletins.  Excellent coverage and reporting.

HYA
STP estimated from PNSBOX reports using inverse distance weighting of vicinity reports within 5 miles of the station.
http://en.wikipedia.org/wiki/Inverse_distance_weighting

Trace amounts for SAT derived from METARs.

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Snow-to-liquid ratio (SLR) not reported for some stations with measurable snowfall b/c significant liquid and / or freezing precipitation also occurred during the verification period.