NE.Wx Snowfall Forecast Contest

Complete Results @ http://www.newx-forecasts.com/

Follow the left-panel link from '26^th Annual Snow Storm Contest > Verified Forecasts > ‘Storm #2’ to see the complete forecasters’ verification table by station.

In the table ...

Yellow cells indicate the best score in the category.

Forecast STP cells: yellow if within +/- 5% of observed STP.

Blue (Red) cells indicate the 1^st (4^th) quartile

SUMSQ: sum of square errors (measure of forecast accuracy accounting for magnitude and distribution of snowfall)

STP: storm total precipitation

TAE: total absolute error
AAE: average absolute error

Final Standings and Measures of Skill - all Forecasters

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Station by Station Comparison of Top 4 Forecasts and Observed Storm-total Snowfall (STP)

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Perfect Forecasts (Batting Average - Forecast Stations with No Error)

Best Station Forecasts (Batting Average - Forecast Stations with Lowest Absolute Error)

Best Station Forecast Busts (Batting Average - Forecast Stations with Highest Absolute Error)

Skill v. NWS ER WFOs

SKILL: positive (negative) skill value indicates a forecast/s improvement (degradation) relative to the current NWS forecast at entry deadline.

BIAS: arithmetic difference between the average Forecast snowfall and the average Observed snowfall (averageForecast) – averageObserved).

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Consensus and Extrema Forecasts with Observed Snowfall

Consensus forecast best @ ABE

NWS forecast best @ BGR …ISP …ACY

MAX forecast best @ MDT

MAX forecast less than observed @

MIN forecasts best @ CAR …CON …HYA …PVD …BDR … ALB …JFK …PHL …EWR …BWI …IAD … DCA

MIN forecasts more than observed @ BDR …PHL … EWR … DCA

* all evaluated subjectively

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Total Absolute Error and SUMSQ Error

Strong correlation (R = 0.990) between SUMSQ and TAE Z-scores

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Forecast by Observed Snowfall Scatterplots (Top 4 Forecasts)

A Forecast’s dashed BLUE trend line above (below) solid RED Observed snowfall line ==> over (under) forecast

R² value indicates how well the forecast captured the observed snowfall’s variability … i.e., R² = 0.874 ==> the forecast captured ~87% of the observed snowfall’s variability.

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Storm-total Snowfall Verification

Verification of storm-total snowfalls for SUN and MON based on reporting from CDUS41 (CLI) ... CXUS51 (CF6) ... METARs ... and PNS bulletins issued by NWS.

Good coverage for station snowfalls but some spotty/questionable reporting of melt water.

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Missing/questionable melt-water values precludes accurate SLR calculations for some stations

HYA

STP derived from inverse distanced-weighted scheme based on vicinity reports from PNSBOX.

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Snow-to-liquid ratios (SLR) less than 8:1 are not reported for stations with measurable snowfall b/c significant liquid and / or freezing precipitation also occurred during the verification period.

The 'TOT SLR' field is a quantity-weighted AVERAGE of those stations with at least an 8:1 SLR.

A table of numbers and letters

Description automatically generated

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Stations observing >= Trace: 24 (89%)
Stations observing > Trace: 22 (81%)

Given a station had measurable snowfall; stations observing at least:
4” – 8 (30%)

6” – 3 (11%)

8” - 0 (0%)

MAX snow melt-water (minimum SLR 8:1)
- uncertain b/c multiple stations have missing or questionable melt-water data

MAX precipitation (frozen + freezing + liquid)
- uncertain b/c multiple stations have missing or questionable melt-water data

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New daily snowfall record(s)
None

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Daily snowfall data table

ORANGE cells: new daily record
GREY cells: data source(s) - PNS and / or METARs or inverse distance weighting
Trace amounts (displayed as 0.05") not included in STP

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