Winter '20 / '21 - VCP 32: Another Month At Least

 

Winter '20 / '21 - 'Season-total' Snowfall Forecast Contest: DEC Totals

DEC-20 snowfall summary by forecast station.
Rank ordered descending by percent of monthly period-of-record-normal (P-O-R-N).

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Green ==> 75th - 100th percentile
White ==> less than 75th and greater than 25th percentile (inter-quartile range)
Red ==> 0 - 25th percentile

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DEC Forecast Station Highlights
15 stations above normal monthly snowfall
5 stations at least 200% of monthly normal

BGM
30" above normal
68% of its normal season-total snowfall

CON
53% of its normal season-total snowfall

ALB
47% of its normal season-total snowfall

Biggest Losers
RDU ... DCA ... ACY ... and ORF observed less than 10% of normal monthly snowfall

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Season-Total-to-Date

DEC P-O-R-N contributes 203.3" (22%) toward the season-total snowfall (D-J-F-M) of 929".
DEC-20 observed snowfall:  292" (44% above P-O-R-N; 31% of season-total snowfall)

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

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Teleconnections

AO / NAO / PNA data

Winter '20 / '21 - Coastal Teaser #1

UPDATE:  02-JAN-21 @ 9 AM EST
Not happenin' ...

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UPDATE:  01-JAN-21 @ 6:41 PM EST

Today/s 12z / 18z progs suggest too few stations in play for a contest-worthy snow storm.

Will evaluate 00z / 06z runs just in case ...

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Originally posted:  31-DEC-20 @ 6:41 PM EST

Cyclogenesis progged early this weekend in the Gulf of Mexico on the trailing end of a cold front attending FRI/s storm moving NE through the Mid-West ... Great Lakes ... and New England may turn into a long duration contest-worthy snow storm for the northern half of the forecast area come SUN.

Should the present trend in NWP output continue ...

Call for Forecasts:  FRI ... 01-JAN-21
Deadline for entries:  10 PM EST ... SAT ... 02-JAN-21
Verification period:  12:01 AM EST ... SUN ... 03-JAN-21 till flakes stop accumulating

Watch this space ...

Winter '20 / '21 - Snow Storm #1: FINAL Results

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

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

Station by Station Comparison of Top Forecasters

Winter '20 / '21 - Snow Storm #1: Preliminary STP Verification

Accumulation-weighted SN:H2O

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

HYA STP estimated by applying inverse distance weighting interpolation of five timely reports within 3 SM of the station carried by the BOSPNS bulletin.

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

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Stations observing >= 0.1"  20 (74%)

Given a station had measurable snowfall; stations observing at least ...
4" - 16 (76%)
8" - 11 (53%)
12" - 7 (33%)
18" - 3 (14%)
24" - 2 (10%)

MAX snow melt-water (minimum SLR 10:1)
BGM:  2.8"
ALB:  2.0"
BOS:  1.3"

MAX liquid precipitation (frozen + freezing + liquid):
BGM:  2.8"
ACY:  2.06"
ALB:  2.0"

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New daily record(s)
16-DEC-20
BDR - 6.5" (2"; 1970)
ISP - 5.7" (1.5"; 1995)
JFK - 3.8" (1.3"; 1981)

17-DEC-20
BGM - 26.4" (9.8"; 1973)
CON - 24.2" (8.6"; 1970)
ALB - 19.7" (11.1"; 1970)
BOS - 12.7" (6.4"; 2013)
ORH - 10.5" (9.9"; 1970)
BDL - 7.8" (6.5"; 2016)
PVD - 6.4" (4"; 1961)
EWR - 5.9" (3"; 2016)
JFK - 3.4" (3"; 2016)

Storm total snowfall
Image courtesy NOHRSC

SFC analysis:  09z ... 17-DEC-20
Image courtesy DOC / NOAA / NWS / NCEP / WPC

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Please report any errors in Comments along with a link to the correct data.
FINAL results expected NLT SAT evening.

Winter '20 / '21 - Snow Storm #1: The Forecasts!

MDT
07-FEB-67

Forecasters
Rookie     2
Intern       1
Journey    1
Senior      15
GOVT     1
PWSP      1
TOT        21

NEWxSFC welcomes Rookie Forecasters NJTom and Leigh Rosenthal along with our returning veterans.  Congratulations to Briannavaught for her promotion to Intern Forecaster and kc2dux to Journeyman Forecaster.

Don Sutherland retains his title as Chief Forecaster this winter b/c there was only one 'contest-worthy' snow storm last winter -- minimum three storms required -- to hold a valid contest and declare a winner.

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Forecasters ranked by ascending storm-total precipitation (STP)

BLUE ==> 25th percentile
RED ==> 75th percentile
WHITE STP cells range between the 25th and 75th percentile 

Read more »

Winter '20 / '21 - Snow Storm # 1: RAW Forecasts

here ...

Winter '20 / '21 - Snow Storm #1: Call for Forecasts!

NYC
19-DEC-45

Rousing start to NEWx/s 22nd Annual 'Snow Storm' Forecasting Contest!

Rapidly deepening coastal LOW ... cold air damming ... and a potent fast-moving mid-level short wave combine mid-week for a rare 'contest-worthy' event in DEC.

Everyone is welcome to enter a forecast.

You also get the chance to see how well your forecast stacks up against NWS Eastern Region Weather Forecast Offices.  Turns out they/ve been fairly easy to beat!

Forecast element: each station/s storm-total snowfall

Deadline for entries: 10:00 PM EST ... TUE ... 15-DEC-20
Verification begins: 12:01 AM EST ... WED ... 16-DEC-20
Verification ends: 11:59 PM EST on the day when accumulating flakes stop flyin'.
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Enter your forecast at the NEWxSFC/s home page at http://www.newx-forecasts.com/
Follow the top-of-page link from 'Enter Storm 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).

The snowfall forecasting contest for Snow Storm #1 may be cancelled prior to the deadline if at least six-to-eight stations are unlikely to observe at least a 4" storm-total snowfall.

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

Winter '20 / '21 - North Atlantic Oscillation (NAO): Analog Composites of 500 mb Height and 2-meter Temperature Anomalies ... as of NOV-20

 NOV:  +2.54 🔥🔥🔥
Only two other NOVs had a higher index ('78 +3.04; '93 +2.56)

TL;DR  This winter/s average NAO index expected to be positive ( >0 ).

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Analogs and weights for composites:
'03 / '04 (1)
'99 / '00 (1)
'91 / '92 (1)
'93 / '94 (1)
'15 / '16 (1)

Each analog's average NAO for D-J-F was > 0.

NAO/s analog winters are assessed against the upcoming winter/s expected states of:
- ENSO (MEI moderate - trending weak La Nina)
- QBO-W < 10
- PDO (cool)

We removed '03 / '04 ... '91 / '92 ... and '15 / '16 from further consideration b/c they were +ENSO winters.  Winter '93 / '94 had QBO-E so it too drops out.

Winter '99 / '00 survives with its weak La Nina --- QBO-W < 10 ... and a cool PDO.

Read more »

Winter '20 / '21 - Snow Storm #1: Contest-worthy or What?

The winter/s first nor'easter has moved into the Canadian Maritimes but not before laying down an impressive stripe of early season snowfall across northern portions of the forecast area.

On occasion the prestorm NWP output and expert guidance suggest a snowstorm will not be contest-worthy only to turn out to have been a contender.

Did NEWxSFC miss the call on this one?

Not every snowstorm expected to affect the forecast area will trigger a contest. The criteria applied to decide whether a storm is contest-worthy are loosely defined as one expected to:

- Affect at least six to eight forecast stations ...
- Produce more than a nuisance snowfall (>= 4") ...
- Be well progged by NWP ~36 to 48 hours before snow is observed at any one station.

So ... did the weekend storm rise to the occasion or fall short as expected?

Read more »