CONTEST STATUS - Updated: SAT ... 11-APR-20 @ 8:30 PM EST

Winter '19 / '20 - Snowfall Forecast Contests
21st Annual 'Snow Storm' Snowfall Forecast Contest
Season ended as quickly as it started.
No winner this go'round ... too few storms (minimum of three required)

Snow Storm #1 (01-DEC-19)
FINAL Results here

---
19th Annual 'Season-total' Snowfall Forecast Contest
FINAL Results here

---
Winter '18 / '19 - Snowfall Forecast Contests
20th Annual 'Snow Storm' Snowfall Forecast Contest
FINAL Results here

---
18th Annual 'Season-total' Snowfall Forecast Contest
FINAL Results here
Forecaster verification table here

Sunday, December 15, 2019

Winter '19 / '20 - North Atlantic Oscillation (NAO): Leading Analogs' 5H and 2mT Composite Anomalies ... as of NOV-19

NOV-19 NAO:  +0.28

Same analog years as those associated with NAO/s OCT-19 analysis but with a shuffled ranking.
Winter / AVG NAO
80-81 / 0.487
08-09 / 0.077
12-13 / 0.227
14-15 / 1.197
16-17 / 1.113


Weighted NAO Analogs for Winter '19 / '20:  5H GPHa (l) & 2mTa (r)

- Positive 5H GPHa over west CONUS & negative 5H GPHa over eastern third of CONUS ==> Ridge-W / Trof-E flow regime
- Positive 5H GPHa INVOF Azores ==> NAO > 0
- Negative 5H GPHa over North Pole ==> AO > 0
- Negative 5H GPHa INVOF Great Lakes and along East Coast ==> Miller B-type storms
- Negative 2mTa along East Coast and most of New England

---
At the 95% confidence level ... the Chi-square 'Test of Independence' shows the state of NOV/s NAO and the average NAO state for the ensuing D-J-F period are not independent.  They are related and have predictive value.

Over the NAO/s 69 year period-of-record ... the data show when NOV/s NAO is positive  ... there's a 73% chance the winter/s average NAO will be also positive.

The present analog years add weight to the Chi-square analysis suggesting NAO/s average state this winter will be positive.  An important caveat:  four of the five NAO analogs years occurred during 'cold' ENSO winters.  Winter 14 / '15 was the exception with a weak El Nino (SSTa 0.6°C).  All forecast stations ... in total ... measured 50% above normal snowfall that winter.

---
Key
5H - 500 mb
2mTa - 2 meter temperature anomaly
GPHa - geopotential height anomaly
CONUS - continental United States
INVOF - in the vicinity of
ENSO - El Nino Southern Oscillation
SSTa -  sea surface temperature anomalies

No comments: