Winter '24 / '25 - 'Season-total' Snowfall Forecast Contest: FEB Snowfall Totals

US-13 to Penny Hill
New Castle ... DE (1922)

FEB-25 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 4th and greater than 1st quartile (inter-quartile range - IQR)
Red ==> 1st quartile

'Obs' reporting '0.05' denote 'Trace' amounts (observed but unmeasurable)

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Forecast Station Highlights - FEB
15 stations observed at least 100% of their monthly climo snowfall.
ORF and SBY led the way with over 400% and 300% ... respectively.
Even RDU got into the action with 113% of P-O-R-N.

Biggest Losers
6 northern M-A stations observed less than 80% of their P-O-R-N.

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Season-total-to-Date
FEB P-O-R-N contributes 266" (28%) toward the season-total (D-J-F-M) snowfall of 936".
FEB-25 observed snowfall:  308" (116% of monthly P-O-R-N; 33% of P-O-R-N season-total snowfall).

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Teleconnections

AO / NAO / PNA data

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DEC snowfall totals here
JAN snowfall totals here
FEB snowfall totals here
MAR snowfall totals here

Winter '24 / '25 - Snow Storm #4: FINAL Results and Storm Summary

BOS - Morrissey Boulevard
FEB-78

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

SUMSQ:  sum of square errors (")
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 error.

- R^2:  how well the forecast 'explained' the variability of the observed snowfall (i.e., an R^2 of 0.710 means the forecast explained 71% of the observed snowfall's variability).

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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 (negative) skill values indicate the degree of a forecast/s improvement (degradation)
compared to NWS forecasts.

- Bias:  the arithmetic difference between the average Forecast snowfall and the average Observed snowfall (avgForecast - avgObserved).

Winter '24 / '25 - Snow Storm #4: Preliminary STP Verifications

Presidents Day
19-FEB-79

UPDATED 18-FEB @ 10:30 AM ET to include snowfall for CAR ... BGR ... and BGM plus trace amounts for several other stations on 17-FEB.

h/t RS

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Preliminary verification of storm-total snowfalls based on reporting from CDUS41 (CLI) ... CXUS51 (CF6) ... METARs ... and PNS bulletins issued by NWS.

Good coverage and reporting.

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HYA
STP derived from an inverse distanced-weighting technique using vicinity STP reports
from Barnstable county carried in the BOXPNS bulletin as inputs.

Summary SLR value is quantity-weighted.
Station SLRs < 8 are not reported b/c of probable contamination from liquid and/or freezing precipitation.

Read more »

Winter '24 / '25 - Snow Storm #3: Preliminary STP Verifications

Knickerbocker storm
DC (28-JAN-1922)

Preliminary verification of storm-total snowfalls for FRI and SAT based on reporting from CDUS41 (CLI) ...CXUS51 (CF6) ... METARs ... and PNS bulletins issued by NWS.

Good coverage and reporting.

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HYA
STP derived from inverse distance-weighting technique using vicinity STP reports from Barnstable county carried in the BOXPNS bulletin as inputs.

Summary SLR value is quantity-weighted.
Stations with SLR < 8 are not reported b/c of probable contamination from liquid and/or freezing precipitation.

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Stations observing >= Trace:  25 (93%)
Stations observing > Trace:  18 (67%)

Given a station had measurable snowfall; stations observing at least:
4" - 10 (37%)
6" -  1 (4%)
8" - 1 (4%)
10" - 1 (4%)

MAX snow melt-water (minimum SLR 8:1)
BDR - 0.58'
ORH - 0.51"
PVD - 0.46"

MAX precipitation (frozen + freezing + liquid)
JFK - 0.72"
JFK - 0.69"
EWR - 0.64"

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New daily snowfall record(s)
None

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Daily snowfall data table

ORANGE: new daily record
GREY:  STP derived from PNS or METARs or inverse distance weighting

Trace amounts (displayed as 0.05") are not included in STP or SLR calculations.

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Areal distribution of storm-total snowfall

Image courtesy NOHRSC
https://www.nohrsc.noaa.gov/

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SFC analysis:  06z ... 09-FEB-25

Image courtesy DOC / NOAA / NWS / NCEP / WPC
https://www.wpc.ncep.noaa.gov/html/avnsfc.shtml

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Please report any errors in Comments along with a link to the correct data.
FINAL results expected NLT TUE evening on or about 9 PM ET.

Winter '24 / '25 - 'Season-total' Snowfall Forecast Contest: JAN Snowfall Totals

NYC
26-DEC-47

JAN-25 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 4th and greater than 1st quartile (inter-quartile range - IQR)
Red ==> 1st quartile

'Obs' reporting '0.05' denote 'Trace' amounts (observed but unmeasurable)

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Forecast Station Highlights - JAN
Over-achievers of the month:  SBY @ 283% of monthly P-O-R-N and ORF @ 190%.
9 stations observed at least 100% of its monthly climo snowfall.

Biggest Losers
4 stations observed less than 50% of their monthly climo.

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Season-total-to-Date

JAN P-O-R-N contributes 278" (30%) toward the season-total (D-J-F-M) snowfall of 936".
JAN-25 observed snowfall:  221" (79% of monthly P-O-R-N; 24% of P-O-R-N season-total snowfall).

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Teleconnections

AO / NAO / PNA data

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DEC snowfall totals here
JAN snowfall totals here
FEB snowfall totals here
MAR snowfall totals here

Winter '24 / '25 - Snow Storm #2: FINAL Results and Storm Summary

BWI - Mount Vernon Place (1938)

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

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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 error.

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Comparison of Top 4 Forecasts and Observed Snowfall by Station

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Forecaster Skill Score (measured against NWS ER WFOs)

- Positive (negative) skill values indicate the degree of a forecast/s improvement (degradation) compared to NWS forecasts.
- Bias:  the arithmetic difference between the average Forecast snowfall and the average Observed snowfall (avgForecast - avgObserved).

Winter '24 / '25 - Snow Storm #2: Preliminary STP Verifications

NYC - West Broadway at Spring Street
(1983)

Preliminary 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 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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Summary SLR value is quantity-weighted.
Stations with SLR < 8 are not reported b/c of contamination from liquid or freezing precipitation.

Read more »

Winter '24 / '25 - 'Season-total' Snowfall Forecast Contest: DEC Snowfall Totals

DC
Connecticut Ave and Chevy Chase Circle - 1942

DEC-24 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 4th and greater than 1st quartile (inter-quartile range)
Red ==> 1st quartile

'Obs' reporting '0.05' denote 'Trace' amounts (observed but not measurable).

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DEC Forecast Station Highlights
1 station observed at least 100% of its monthly climo snowfall (BGM).

Biggest Losers
9 stations with less than 10%.
2 stations observed trace amounts (displayed as 0.05").
3 stations not a single flake ... ice pellet ... or hailstone observed.

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Season-total-to-Date
DEC P-O-R-N contributes 207" (22%) toward the season-total (D-J-F-M) snowfall of 936".
DEC-24 observed snowfall:  130" (63% of monthly P-O-R-N; 14% of P-O-R-N season-total snowfall).

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Teleconnections

AO / NAO / PNA data

Winter '24 / '25 - Snow Storm #1: Preliminary STP Verification

Smithstonian - 1920s

Preliminary 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 and reporting.

Exceptions
SBY
NWS Climatological Report (Daily - CLI) carried 'MM' for SAT snowfall-total and 0.53" liquid.

NWS WFO Monthly/Daily Climate Data (CF6) carried 8.5" and 'M' for liquid.

STP derived by an inverse distance weighting scheme with AKQ and PHI vicinity reports carried in their PNS bulletins for Sussex county ... DE and Worcester and Wicomico counties in MD came to 8.5".

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Read more »

Winter '23 / '24 - 23rd Annual 'Season-total' Snowfall Forecast Contest: FINAL Results

BWI - Park Avenue (1948)

Congratulations to Senior Forecaster WXCHEMIST for issuing the best 'season-total' snowfall forecast for Winter '23 / '24.  WXCHEMIST also issued the best 'season-total' snowfall forecast for Winter '13 / '14.

Complete forecaster verification table at the Contest/s web site.

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

BLUE ==> 1st Quartile
WHITE / GREY ==>  Interquartile range
RED ==> 4th Quartile
ORANGE:  Winter '22 / '23 Chief 'Season-total' Forecaster (winner of  '21 / '22 contest)

The '%MPRV over PORN' metric indicates how much the forecast was better or worse than the Period-Of-Record-Normal (P-O-R-N).  Skillful forecasts beat P-O-R-N.

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Read more »

Winter '23 / '24 - 'Season-total' Snowfall Forecast Contest: MAR Snowfall Totals

BOS - Adams Square
(14-FEB-40)

MAR-24 snowfall summary by forecast station.

Rank ordered descending by percent of monthly period-of-record-normal.

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

'Obs' reporting '0.05' denote 'Trace' amounts (observed but not measurable)

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Read more »

Winter '23 / '24 - Snow Storm #3: FINAL Results and Storm Summary

BOS - Fenway Park
(01-APR-97)

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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Forecaster Skill Score (measured against NWS ER WFOs)

Skill: positive values indicate the forecast/s percentage improvement over NWS forecasts.

Bias:  the arithmetic difference between the average Forecast snowfall and the average Observed snowfall (avgForecast - avgObserved).

Winter '23 / '24 - Snow Storm #3: STP Verification - Preliminary

VT - Marshfield cemetery (1953)

Preliminary verification of storm-total snowfalls for WED though FRI based on reporting from CDUS41 (CLI) ... CXUS51 (CF6) ... METARs ... and PNS bulletins issued by NWS.

Excellent coverage and reporting.

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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 the quantity-weighted average of those forecast stations with at least an 8:1 SLR.

Read more »

Winter '23 / '24 - Snow Storm #2: FINAL Results and Storm Summary

MA - Rte 128
FEB-1978

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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Forecaster Skill Score (measured against NWS ER WFOs)

Positive skill values indicate the degree of a forecast/s improvement over NWS forecasts.

Bias:  the arithmetic difference between the average Forecast snowfall and the average Observed snowfall (avgForecast - avgObserved).

Winter '23 / '24 - Snow Storm #2: STP Verification - Preliminary

NYC - Central Park
West Historic District (20-MAR-56)

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

Excellent coverage and reporting.

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HYA
STP derived by applying an inverse distance weighting scheme to BOSPNS vicinity reports from Barnstable county.

Snow-to-liquid ratios (SLR) less than 8:1 are not reported for some 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.

Read more »

Winter '23 / '24 - Snow Storm #1: STP Verification - Preliminary

BOS - Congress and Water Streets
13-APR-33

Preliminary verification of storm-total snowfalls from 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.

Snow-to-liquid ratio (SLR) less than 8:1 are not reported for some 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.

Read more »