Winter '10 / '11 - Coastal Teaser #2
Look familiar?
GooFuS has a coastal storm on the 7th as well; however...its genesis is in the northern stream leaving the SW bowling ball behind.
Snowfall forecasting contests for 27 stations across New England and the Mid-Atlantic regions ... since 1999
Look familiar?
GooFuS has a coastal storm on the 7th as well; however...its genesis is in the northern stream leaving the SW bowling ball behind.
Beautiful imagery from NASA/s Earth Observatory showing surface air temperature anomalies resulting from persistently negative Arctic Oscillation. Red (blue) areas are warm (cold) surface air temperature anomalies. "This image shows the temperature of the land surface for December 3-10, 2010 compared to the average temperature for the same period between 2002 and 2009."
The monthly Arctic Oscillation index has been below zero...15 out of 18 months since JUN-09. The AO fell to an all time low of -4.266 in FEB-10. Last winter's D-J-F average was -2.587.
Persistent HIGH pressure...often associated with a weak polar vortex (PV)...over the north pole allows arctic air to drain into low latitudes. Daily AO values have been negative since mid-NOV. This goes against type considering the QBO is in its westerly phase where the AO is typically positive...a consequence of a strong...cold PV.
From the NYT...
"But for all its bluster and powder, the monster storm was technically a blizzard only outside of Manhattan. The winds in Central Park topped out at 36 miles per hour but were not sustained over a period of three consecutive hours, nor was the visibility under a quarter of a mile for that period — both requirements to qualify as a blizzard.Blizzard conditions were observed at JFK but not at LGA where the SFC visibility never went below 1/4SM.
“We didn’t quite make the criteria in Central Park,” said Matt Scalora, a meteorologist with the National Weather Service in Central Park. “But we did meet the criteria at J.F.K. Airport and La Guardia,” he added."
03z SFC analysis |
NYC/s 8th Avenue 27-DEC-47 |
15 entries
3 Intern forecasters
3 Journeyman forecasters
9 Senior forecasters including Chief Forecaster Iralibov
Great turn-out and a great storm for the season opener.
All 27 stations in play making this an excellent test of synoptic-scale snowfall forecasting ability.
All forecasts have been posted to the Contest's web site. Follow the link from Winter '10 / '11 Storm Contest > Forecasts > Storm #1.
Entries are ranked in ascending order by 'storm-total' snowfall. Please check you entry for accuracy.
Broad range of expected storm-total snowfall...
Min: 80" (Weathermbug)
Max: 354" (Roger Smith)
Avg: 233"
Median: 254"
STD: 77"
Off-shore waters of GA starting to churn...
MODEL DIAGNOSTIC DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
143 PM EST FRI DEC 24 2010
VALID DEC 24/1200 UTC THRU DEC 28/0000 UTC
INITIALIZATION ERRORS IN NUMEROUS DIAGNOSTIC QUANTITIES...INCLUDING HEIGHT/VORTICITY FIELDS/RH...ARE EVIDENT IN BOTH THE 12Z NAM/GFS WITH SMALL BUT LIKELY SIGNIFICANT SHORTWAVE TROUGHS OVER SOUTH DAKOTA/NEBRASKA ALONG WITH SASKATCHEWAN/MANITOBA...WITH THESE AREAS ALSO NOT PARTICULARLY
RESOLVED OR PREDICTED WELL BY THE 00Z ECMWF.
THUS...THE SPECIFIC PREDICTIONS BY ALL DETERMINISTIC GUIDANCE ARE IN QUESTION...WITH THE RECOMMENDATION TO FOLLOW CONTINUITY...WITH THE FINAL OUTCOME MOST BELIEVED TO LIE BETWEEN THE 06Z GFS AND 00Z ECMWF...WITH ALL
ENSEMBLE GUIDANCE INCLUDING THE SREF MEAN/GEFS MEAN (EXCEPT NOT
THE 12Z VERSION)/ECMWF ENSEMBLE MEAN ALSO CONSIDERED USEFUL TO
ADDRESS THE CONTINUED UNCERTAINTY.
THIS APPROACH DISREGARDS THE SUBSTANTIALLY DEEPER AND WESTWARD SHIFT OF THE 12Z GFS REGARDING THE POWERFUL LOW TRACKING UP THE EASTERN SEABOARD...AND TO A LESSER EXTENT THE 12Z NAM WHICH LIES NEAR THE FAST EDGE OF THE GUIDANCE WITH THE DEVELOPING LOW.
NYC 27-DEC-47 |
Last signal failed to pan-out. Probability a long-shot given the poor odds for warmings with QBO in its positive / west phase....except when sunspot activity is high.
ECMWF hinting again at a break in the polar vortex (PV) last next week.
Note 1) the PV's pending split with separate circulation developing over the pole / central Russia and 2) the yellow area north-west of the Hudson Bay. The yellow indicates warmer temperature at 100 mb which implies a very cold troposphere. The slug of warm stratospheric air originated --- and is usually found -- over Siberia.
Individual forecasts on the Contest web site here.
Extended-range progs from the ECMWF continue to suggest a warming event may be in the offing come mid-DEC...foretelling a cold start to 2011 as the bottom of the Arctic Oscillation (AO) falls out.
Note the forecast of two distinct hi-latitude cyclonic circulation centers at 100 mb...which could be in the process of ingesting the hi-amplitude tropospheric ridges positioned currently over the north Atlantic and the Bering Sea.
Long Island...NY 02-FEB-1934 |
Forecaster Summary
Forecasts in the table below are ranked by storm total precipitation (STP) in ascending order. Blue (red) STP values are below (above) the 25th (75th) percentile of all forecast STPs.
Forecaster Summary
Forecasts in the table below are ranked by storm total precipitation (STP) in ascending order. Blue (red) STP values are below (above) the 25th (75th) percentile of all forecast STPs.
Average STP (93.8") per average number of stations (25) forecast: 3.8".
Nine entries...including two Rookies... one Intern...and six Senior forecasters...issued 229 station forecasts for the winter/s 6th contest snow storm.
Everyone's station forecasts have been posted on the Contest's web site.
Interesting to note...three of the largest season-total snowfalls have occurred in the last 15 years...during a time when NHEMI areal snowfall has been generally well below average...especially during summer.How rare is this winter/s snowfall?