Winter '10 / '11 - Snow Storm #4 - Final Results

SFC Analysis
12z 21-JAN-11

1st - Brad Yehl
SUMSQ: 75.76
SUMSQ Z: -0.945
STP: 7.50 (3)
TAE: 26.50 (2)
AAE: 1.10 (3)

Bride's Maid - Shillelagh
SUMSQ: 79.91
SUMSQ Z: -0.890
STP: 0.80 (2)
TAE: 26.90 (3)
AAE: 1.08 (2)

3rd - TQ
SUMSQ: 95.25
SUMSQ Z: -0.686
STP: 11.50 (6)
TAE: 27.90 (4)
AAE: 1.16 (4)

Honorable Mention - donsutherland1
SUMSQ: 100.19
SUMSQ Z: -0.621
STP: 17.60 (8)
TAE: 24.50 (1)
AAE: 1.07 (1)

SUMSQ: sum of square errors
STP: storm-total precipitation error
TAE: total absolute error
AAE: average absolute error
(rank)

---
Full forecast verification and summary at the Contest/s home page.

Winter '10 / '11 - Snow Storm #4 - Preliminary Verification

Preliminary storm-total snowfalls for Friday from CDUS41...CXUS51...and PNS...as of 8 AM Saturday.

No snowfall report was carried in the NWS PNSBOX bulletin for HYA. Verifying storm-total snowfall of 0.5" was estimated from HYA/s Pxxxx METAR data.

A field formatting error in the data table shows ACY and IAD with 0.1".  Actual STP was a 'trace' (0.05") at both locations.
---
Three new daily records.
FRI...21-JAN-11
BDR BGR - 17.3" (4.3"; 1946)
BOS - 7.3" (6.4"; 2001)
EWR - 4.5" (4.2"; 2001)

---
Please report errors and drop a link to the correct data in Comments.
Final results and storm summary on Sunday.

Winter '10 / '11 - Snow Storm #4 - The Forecasts

11 entries

1 Rookie
2 Intern forecasters
2 Journeyman forecasters
6 Senior forecasters

Snow storm #4...while tame compared to the first three events...put down down respectable storm-total snowfalls over several New England stations.

---
All forecasts have been posted to the Contest's home page.
Follow the link from Storm #4.

Entries are ranked in ascending order by 'storm-total' snowfall.
Please check you entry for accuracy.

Broad range of expected storm-total snowfall...
Min: 72" (donsutherland1)
Max: 147" (MarkHofman)
Avg: 95"
Median: 90"
STD: 21"

Heaviest snowfall axis expected to fall inside BGR - PWM - BOS - PVD - BDL - ORH - CON - BGR

Winter '10 / '11 - Snow Storm #4 - Raw Forecasts

Raw forecasts here.

Winter '10 / '11 - December Snow Cover

From NCDC...

"The Northern Hemisphere snow cover extent during December 2010 was much above-average, marking the fourth largest December snow cover extent on record — behind December 2009, 1985, and 1970."

"During December 2010, the North American snow cover extent was above average, ranking as the seventh largest on record. This marks the fourth consecutive December with above-average snow cover extent for the continent."

Global Snow Report here.
National Snow and Ice Report here.

Winter '10 / '11 - Snow Storm #4 - Call for Forecasts

Union...Maine
JAN-1926

Miller-B (.pdf) cyclogenesis forecast to occur off the Delmarva peninsula early FRI morning.

Progs aren/t all that juiced nor are the powerhouse dynamics we/ve seen with previous storms evident until the system lifts out to the NE.

Even so...the storm appears to be contest-worthy.

The contest may be canceled prior to the deadline if NWP indicates a fizzling event.

-----
Deadline for entries: 10:30 PM EST THU...20-JAN-11
Forecast element: storm-total snowfall

Verification begins: 12:01 AM EST FRI...21-JAN-11
Verification ends: 11:59 PM EST FRI...21-JAN-11

Enter your forecast at the Contest's home page here.
Follow the link from 'Enter Storm Forecast.'

---
As always...there/s no cost...or fee...or advertising...or annoying requests for personal information to enter a forecast. It's just a fun exercise among winter wx enthusiasts to see who can make the best synoptic-scale snowfall forecast.

If you are issuing your first forecast this winter...or you entered the 'season-total' forecast contest...you/ll need to create an account (user name / password / valid e-mail...if you want a copy of your forecast sent to your Inbox).

Want to be notified via e-mail when a 'Call for Forecasts' is issued?
Send your request to newx at newx-forecasts dot com.

Winter '10 / '11 - Northeastern Snowfall Impact Scale - Return Periods

The heavy snowfall of late December scored a 4.92 on the Northeastern Snowfall Impact Scale (NESIS).  It ranked 59th out of 76 events.

How often can a storm of this impact be expected to affect the NE?

Plotting the Gumbel distribution curve for the 76 NESIS events...we can estimate the return period of a 4.92 magnitude snow storm as 3.72 years.

What about the estimated return periods for the 'Top-5' NESIS storms?
Was the March-93 'Superstorm' really the 'Storm of the Century?' The Great Blizzard of JAN-96...ranked 2nd highest NESIS...was another memorable storm of the late 20th century.

How often can storms of such extreme impact be expected?

'Top-5' NESIS Events and Index...
12/14-MAR-93: 13.20
6/8-JAN-96: 11.78
2/5-MAR-60: 8.77
15/18-FEB-03: 7.50
2/5-FEB-61: 7.06

Gumbel distribution for 76 NESIS events

Return period...in years...for the 'Top-5' NESIS events...
12/14-MAR-93: 340
6/8-JAN-96: 153
2/5-MAR-60: 28.5
6/7-FEB-03: 14.2
2/5-FEB-61: 11.2

The return period for the MAR-93 Superstorm is more than twice as long as its nearest neighbor...the Great Blizzard of JAN-96.  Consider yourself lucky to have been alive when these genuinely historic storms occurred b/c it'll likely be a long...long time before a snow storm will have such a severe impact on the NE again.

Winter '10 / '11 - Interim Standings - #1

After three snow storms...

Under the 'two-thirds' rule...the best 'two out of three' z-scores are used to compute the interim standings.  After Snow Storm #4...your top three z-scores will be used.

Z-scores are used to standardize or normalize the errors from each storm so at the end of the season...the scores can be averaged.

An expanded data table with other measues of forecaster skill at the Contest's home page.

Winter '10 / '11 - Forecaster Master Database

The forecaster master database has been updated here.

The database (.html) has each forecast verification element by forecaster...such as Sum of Square Errors (SUMSQ)...Total Absolute Error (TAE)...Average Absolute Error (AAE)...and the Coefficient of Determination (RSQ).  These 'measures of skill' are described at the Contest's web site here as part of last year's interim/final 'regular season' standings (scroll down).

Winter '10 / '11 - Snow Storm #3 - Final Results

12z 12-JAN-11 

1st - emoran
SUMSQ: 423.59
SUMSQ Z: -1.115
STP: 1.20 (2)
TAE: 76.80 (2)
AAE: 2.84 (2)

2nd - donsutherland1
SUMSQ: 430.73
SUMSQ Z: -1.091
STP: 39.75 (6)
TAE: 72.35 (1)
AAE: 2.68 (1)

3rd - Donald Rosenfeld
SUMSQ: 430.92
SUMSQ Z: -1.090
STP: 4.40 (3)
TAE: 84.70 (5)
AAE: 3.14 (5)

00z 13-JAN-11

Honorable Mention - Brad Yehl
SUMSQ: 484.58
SUMSQ Z: -0.908
STP: 42.15 (7)
TAE: 84.05 (4)
AAE: 3.11 (4)

SUMSQ: sum of square errors
STP: storm-total precipitation error
TAE: total absolute error
AAE: average absolute error
(rank)

---
0.19" SUMSQ error difference between 2nd and 3rd place forecasts.

Mark Hofmann came within 0.1" of the observed storm-total snowall (214.9") for all stations.

Full forecast verification and summary at the Contest/s home page.