NE.Wx Snowfall Forecast Contest

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

Follow the left-panel link from '25^th Annual Snow Storm Contest > Verified Forecasts > ‘Storm #1’ to see the complete forecasters’ verification table by station.

In the table ...

Yellow cells indicate the best score in category.

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

Blue (Red) cells indicate the 25% (75%) percentile.

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 - 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 (decline) over the NWS forecast.

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

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Consensus Forecasts … Extremes … and Observed Snowfall

Consensus forecast best @ CON … PVD

MAX forecast best @ PWM … BTV … ORH

MAX forecast less than observed @ PWM

MIN forecasts best @ BGR … BOS

MIN forecasts more than observed @ none

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Total Absolute Error and SUMSQ Error

Strong correlation (R = 0.975) between SUMSQ and TAE Z-scores

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Forecast by Observed Snowfall Scatterplots (Top 4 Forecasts)

A Forecast dashed 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 SAT and SUN based on reporting from CDUS41 (CLI) ... CXUS51 (CF6) ... METARs ... and PNS bulletins issued by NWS.

Excellent coverage and reporting.
HYA

Derived from PNS vicinity report carried by BOS ... inspection of NOHRSC digital snowfall plot ... and METARs.

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

The 'TOT SLR' field is a quantity-weighted average.

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Stations observing >= Trace: 23 (85%)
Stations observing > Trace: 14 (52%)

Given stations had measurable snowfall; stations observing at least:
4" - 8 (30%)
8" - 5 (19%)
12" - 2 (7%)

MAX snow melt-water (minimum SLR 8:1)
BTV - 1.25"
BGM - 0.32
BGR - 0.25

MAX precipitation (frozen + freezing + liquid)
PVD - 2.91"
BOS - 2.55"
ORH - 2.20"

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New daily snowfall record(s)
none