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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| 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.
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| MDT 07-FEB-67 |
BLUE ==> 25th percentile
RED ==> 75th percentile
WHITE STP cells range between the 25th and 75th percentile
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| NYC 19-DEC-45 |
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.
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.
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?
Forecasters: 22
Forecasters also compete against the Period-of-Record-Normal (P-O-R-N) and Consensus.
Forecaster table ranked by season-total snowfall
 |
| NEWxSFC/s Director of Season-total Snowfall Forecasting |
Verification:
NWS climate reports (CLM or CF6)
Low. Score. Wins.
Deadline for entries: MON ... 30-NOV-20 @ 11:59 PM EST (01-DEC-20 @ 4:59 UTC)
Visit the Contest's website to enter your forecast.
Follow the link at the top right corner of the page to 'Enter Season-total Forecast.'
Update your forecast as often as you want prior to the deadline.
Only your last entry gets verified.
No surprise ... all cool ENSO winters are not created equal.
Some are weak or moderate or strong.
Some associated with QBO-East and some with QBO-West.
During the analysis period between 1950 and 2012 ... most La Niña winters occurred with QBO-E.
Of the winters depicted below ... 15 of the 21 (~71%) were QBO-E.
Taken at face value M-A snow crows suffer the most ...
The NOAA analysis of Rutgers' Global Snow Lab data does not account for the different categories of La Nina episodes (weak ... moderate ... strong) and it has an end date of 12 years ago. Since then ... there have been three La Nina winters - '10 / '11 ... '11 / '12 ... and '17 / '18.
Relative to season-total snowfall at 28 NEWxSFC stations ...
'10 / '11 - well above average (moderate La Nina)
'11 / '12 - well below average (weak La Nina)
'17 / '18 - above average (weak La Nina)
Image courtesy NOAA Climate
Thread updated periodically as new outlooks and forecasts become available from a variety of credible sources.
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CDC - NOV ...
Analogs and weights for composites:
'70 / '71 (24)
'07 / '08 (5)
'88 / '89 (1)
'95 / '96 (1)
'64 / '65 (1)
MEI analog data table (unranked)
Analog statistic (not shown): sum of squared errors
The MEI is based on five variables:
Sea level pressure (SLP)
Sea surface temperature (SST)
Surface zonal winds (U)
Surface meridional winds (V)
Outgoing Longwave Radiation (OLR)
Analogs and weights for composites:
'61 / '62 (2)
'91 / '92 (0)
'95 / '96 (0)
'99 / '00 (1)
'03 / '04 (0).
Two analogs averaged < 0 over D-J-F
Three analogs averaged > 0 over D-J-F
Little in the way of consensus which isn/t especially unusual for analogs.
We assess NAO/s analog winters with the upcoming winter/s expected states of ENSO (moderate-to-strong La Nina) ... QBO-W ... and (cool) PDO.
Recall ... '95 / '96 of 'Storm of the Century' fame was one of the better winter/s evah; however ... despite its weak La Nina profile ... its QBO-E and warm PDO eliminates the strongest calculated match for Winter '20 / '21 from the running. Analog weight: 0
'91 / '92 drops out as well b/c its winter had a strong a El Niño ... QBO-E ... and a warm PDO. The '03/'04 La Nada winter doesn't make the cut either. Analog weights: 0
The two remaining winters '61 / '62 and '99 / '00 are strong analogs for Winter '20 / '21. Both were moderate La Nina (per MEI) ... QBO-W < 10 ... and a cool PDO. '61 / '62 set snowfall records in more than a few stations. Analog weight: 2
Season-total snowfall for '99 / '00 was above average for southern mid-Atlantic stations and generally below average elsewhere. Analog weight: 1
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The 500 mb and 2m T weighted analyses below are based on the winters of '61 / '62 and '99 / '00.
North Atlantic Oscillation (NAO) analog composites of 500 mb (5H) geopotential height anomalies (GPHa) and 2-meter air temperature anomalies (2m Ta) for Winter '20 / '21.
5H GPHa weighted-composite
Main features:
La Nina ridge over SE CONUS
-PNA
Positive geopotential height anomaly south of Greenland ==> -NAO (??? lo-lat action center)
Storm track across northern CONUS
2m Ta weighted-composite
Main features:
Above normal temperature across the Deep South and SE CONUS
Cold AK ==> warm East
Analog years and weights for composites:
'89 / '90
(3) ... '90 / '91 (2) ... '97 / '98 (2) ... '02 / '03 (1) ... and '15 / '16 (1).
Arctic Oscillation (AO) analog composites of 500 mb (5H) geopotential height anomalies (GPHa) and 2-meter air temperature anomalies (2m Ta) for Winter '20 / '21.
~ 11,000,000 SQ-KM
Under-performing all year ...
6% above P-O-RN (~10,320,000 SQ-KM)
9% above median (~10,080,000 SQ-KM)
Period-of-Record: 53 years
Rank: 19th
2nd lowest past 10 years
16 of past 20 years above P-O-R-N
OCT-19: ~12,700,000 SQ-KM
OCT-20: 14% less than last year
Eurasia snow analog years offer little if any guidance given this winter should have cool ENSO / PDO and QBO-W.
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P-O-RN ==> period-of-record normal
Data courtesy Rutgers University Global Snow Lab
http://climate.rutgers.edu/snowcover/index.php
"The La Nina phase will reach quite a formidable strength at its peak but is expected to start to weaken towards spring 2021."
"Historically, the most typical effect of a La Nina is a strong blocking high-pressure system in the North Pacific."
"North America winter forecast looks fairly solid to be a classical La Nina type winter. Most of western Canada is to expect colder and snowier conditions, along with Alaska.
"The United States expects to see a “dipole” pattern or a “two-faced” winter. The Northern [sic] United States are expected to be normal to colder and wetter. This increases the chance of more snowfall, but more likely towards the western half, and less likely in the eastern parts.
"The Southern [sic] United States can slowly prepare for warmer and mostly
drier than normal winter weather. This however does not imply that [sic] no
cold front can reach the southern states. It just implies that [sic] in a La
Nina pattern, it is much less likely to get frequent cold fronts down to
the very south."
"AER explains how accelerated Arctic warming, known as Arctic amplification, is increasingly disrupting the polar vortex, leading to widespread severe winter weather across the Northern Hemisphere’s mid-latitudes."
https://youtu.be/EMeI4N5dui4
Congratulations to Herb @MAWS for his 1st Place finish.
Herb also placed first in '03 / '04 and '09 / '10.
Forecasters ranked by their Total Absolute Error (TAE)
The '%MPRV over PORN' metric indicates how well the forecaster did compared to climatology [(Period-of-Record Normal (PORN)]. The most skillful forecasts beat climatology
Preliminary sum-total season snowfalls for the verification period 01-DEC-19 though 31-MAR-20 collected from monthly climate bulletins (CLMxxx; CXUS51 ... CXUS52).
MAR-20 snowfall summary by forecast station.
Rank ordered descending by percent of monthly period-of-record-normal (P-O-R-N).
FEB-20 snowfall summary by forecast station.
Rank ordered descending by percent of monthly period-of-record-normal (P-O-R-N).
JAN-20 snowfall summary by forecast station.
Rank ordered descending by percent of monthly period-of-record-normal (P-O-R-N).
DEC-19 snowfall summary by forecast station.
Rank ordered descending by percent of monthly period-of-record-normal (P-O-R-N).
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