Winter '09 / '10 - Snow Storm #3 - Preliminary Verification

Preliminary storm-total snowfalls for Friday and Saturday from CDUS41...PNS...and CF6 bulletins.

No climate report for SBY at post-time. The Salisbury CO-OP observer's 220 PM report carried in AKQNS was used.  Value may be revised if CDUS41 or CF6 bulletins are issued before final verification.

Two new daily records.

SAT...30-JAN-10
ACY - 7.6" (3.6"; 1966)
ORF - 6.1" (5"; 1965)

Please report errors and a link to the correct data in Comments.

Final results and storm summary Monday evening.

Winter '09 / '10 - Snow Storm #3 - The Forecasts

12 entries...including three Rookies...two Interns...and seven Senior forecasters issued 151 station forecasts for this winter/s third contest snow storm.

Forecasts are ranked by storm total precipitation (STP) in ascending order. Blue (red) values are in the 25th (75th) percentile.

Forecasts at the Contest web site.

Consensus for a southern mid-Atlantic event.

Arctic Oscillation heading quickly south while NAO and PNA flat-line.

Surface LOW over LA FRI evening forecast to exit stage left late Saturday and kick-out into the western Atlantic off the coastal Carolinas.

Verification period ends 11:59 PM EST...SAT...30-JAN-10.
Preliminary storm-total snowfall totals will be posted the evening of SUN...31-JAN-10.

Winter '09 / '10 - Snow Storm #3 - Raw Forecasts

Raw forecasts here.

All forecasts will be posted to Contest web site and summary information on the web log by FRI evening.

This snow storm appears to be a marginally contest-worthy storm given its potential impact on a limited number of forecast stations.

Then again...there's an added wrinkle to the forecast with the likelihood of accumulating snowfall over a few northern forecast stations during the verification period.

Winter '09 / '10 - Imminent Stratospheric Warming Event

End of FEB temperature outlook: C-C-COLD!

Winter '09 / '10 - Snow Storm #3 - Call for Forecasts

January's second contest snow storm combines juiced-up southern stream energy and bitter arctic cold from the snowfields of northern Canada.

Precipitation coming from weak low-level warm-advection and jet level divergence...with less than impressive mid-level dynamics as streams phase in confluent zone off the mid-Atlantic coast.

Models have been trending farther south past the few runs such that the bare minimum of stations for a contest-worthy storm are expected to be affected.

Last-minute contest cancellation possible if NWP consensus for the frozen precipitation shield dips below the DC metro area. Cancellation notice will be posted to the Contest web site and web log.

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Deadline: 10:30 PM EST THU...28-JAN-10

Forecast element: storm-total snowfall

Verification begins: 12:01 AM EST FRI...29-JAN-10
Verification ends: 11:59 PM EST SAT...30-JAN-10

Enter your forecast at the Contest web site here.
Follow the link from 'Enter Storm Forecast.'

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

If you are issuing your first forecast this year...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) before submitting your entry.

Winter '09 / '10 - Coastal Teaser #3

NWP model solutions have been advertising a coastal storm late in the week with GooFuS starting the event a day sooner than the ECMWF.

PNA is forecast to peak near +2 STD...AO currently below -1 STD and decreasing...and the NAO is expected to rise sharply from -3 STD ahead of an event that could turn out to be a fair test of Archambault cool-season regime transition and its impact on NE precipitation (.ppt 3.5 mb)

A 'Call for Forecasts' may be issued late Wednesday with a 10:30PM EST deadline on Thursday...if shorter-range progs indicate a contest-worthy snow storm is likely to occur.

Stratosphere is showing signs of another warming during early FEB as the PV shifts away from the pole to a position over Great Britain where it splits in half with an anti-cyclone centered over extreme NE Alaska / NW Canada.

Oft times...it takes ~3 weeks for these signatures to work their way into the troposhere...heralding a return to bitter cold in the east by month's end featuring arctic air mass intrusions from the north pole.

Winter '09 / '10 - Cold Expected to Return in February

From Bloomberg...

"A strengthening El Nino pattern in the Pacific Ocean may lead to a colder February than some forecasters are predicting, according to Bastardi.

“El Nino has broken into moderate territory,” Bastardi said. “February could be brutal in the Northeast.”

"Jim Rouiller, the senior energy meteorologist with Planalytics Inc. in Wayne, Pennsylvania, said he expects cold to make a comeback with the arrival of February.

"Most of northern Europe, from the U.K. to Scandinavia, will be colder than average in February and March, said Andover, Massachusetts-based forecaster WSI Corp.

“Winter will be coming back with a vengeance in February,” Todd Crawford, WSI’s chief meteorologist..."

WSI/s NE CONUS forecast issued in November called for above-normal temperatures in DEC and below-normal in JAN.

Bastardi piles on...

"February is going to go down in memory as a month that was as cold and stormy as December,” predicts Joe Bastardi, chief long-range meteorologist for Accuweather. “It might turn out to be one of the coldest Februaries in the last 115 years.”"

Joe D'Aleo adds...

"“The latest GEM [Global Environmental Multiscale] and ECMWF [European Center for Medium Range Weather Forecasts] model runs are showing colder weather for the remainder of the winter. By the last week of January, we should see cold filling into Canada and then diving back down into the states,”..."

WSI  expects the same in Europe...

"WSI expects temperatures for the approaching period (February-April) to average colder than normal across Scandinavia, UK and most of the mainland, with the exception of parts of Iberia and the Mediterranean states.


"After a brief respite from the bitter cold in late January, this rather extreme winter appears to be gearing up for an encore in February," said WSI Chief Meteorologist Dr. Todd Crawford. "All of the important weather and climate factors that we monitor suggest winter will be coming back with a vengeance in February. This transition back to much colder temperatures is already showing up in two-week forecasts from our computer models, lending more confidence to the colder forecast trend."

True enough...models have been suggesting strong infusions of arctic air from Siberia as February rolls in.

Caveat Consensus.

VCP32 - Now She Says Come In

Winter '09 / '10 - Snow in Spain

"Snow fell in parts of Spain for the first time in half a century Monday as a wave of Arctic cold that has killed scores of people and caused billions of euros in damage to Europe's economy swept southwards.

 

"The southern Spanish city of Seville, which normally enjoys temperatures in January of around 15 degrees Celsius (59 degrees Fahrenheit), shivered under its first snowfall in half a century."

 

Elsewhere...

"Prague has had its heaviest snowfalls in 17 years and hundreds of homes across the Czech Republic were without electricity.

"Meanwhile Albania has been contending with a different type of extreme weather, as disastrous floods engulfed more than 10,000 hectares of farmland."
More...

Turning out to be a memorable winter after a long series of miserable seasons.

Winter '09 / '10 - December Snowfall - New Record for NOAM

Short 44 year period-of-record...

December snow cover over NOAM and the lower 48 rank #1 out of 44...as well as 10th for all months.  Second highest snowcover over the NHEMI.

Area units:  thousand sq. km

North America 
Rank Area Departure Mean
1/44 18137 1523 16615

Contiguous United States
Rank Area Departure Mean
1/44 4161 1292 2869

Canada
Rank Area Departure Mean
4/44 10277 221 10056

Northern Hemisphere
Rank Area Departure Mean
2/44 45862 2660 43202

Eurasia
Rank Area Departure Mean
7/42 27725 1138 26587

Source: Rutgers University Global Snow Lab

Winter '09 / '10 - CONUS Snow Cover

With the mid-point of meteorological winter a week away...

CONUS current areal coverage by snow:  62.7%
CONUS areal coverage by snow last month:  55.5% 

Impressive!

Above normal snow cover in the OH and TN River valleys.

Image courtesy NOHRSC

Winter '09 / '10 - Winter Temperatures and the Arctic Oscillation

From NASA/s Earth Observatory...

"This image illustrates how cold December was compared to the average of temperatures recorded in December between 2000 and 2008. Blue points to colder than average land surface temperatures, while red indicates warmer temperatures. Much of the Northern Hemisphere experienced cold land surface temperatures, but the Arctic was exceptionally warm. This weather pattern is a tale-tell sign of the Arctic Oscillation."

More...

The AO is a response to forcing...not a forcing in and of itself.

What caused the cold outbreak was a stratospheric warming event during late NOV / early DEC.  This caused the polar vortex to slow...split in two...and reverse direction...creating an anti-cyclonic (clock-wise) circulation aloft. The reversal took ~3 weeks to propagate to the surface...creating HIGH pressure over the pole....which in turn created favorable conditions for arctic outbreaks and high-latitude blocking...such as the one currently observed.

These reversal events occur preferentially during years (such as this one) where an east wind is observed in the tropical stratosphere...the quasi-biennial oscillation - QBO...and solar activity (sunspots) is low. Above normal snowfall in eastern Eurasia this fall played a significant role in initiating the stratospheric warming event.

HIGH pressure @high-latitudes is indicative of negative NAO and negative Arctic Oscillation (AO); however...to blame the cold on -NAO / -AO is just plain wrong.

Winter '09 / '10 - ECHAM5

Latest hemispheric sea-level deviation forecasts from ECHAM5.

RED: negative deviations
BLUE: positive deviations

JAN:  Aleutian LOW pressure is forecast to persist as well as the current storm track into the Mediterranean Sea.  Strong HIGH pressure deviations centered over NW Russia suggesting a shift of the high-latitude block now east Greenland will continue to drift.

Pressure configuration over CONUS is suggestive of persistent +PNA flow regime...a continuation of arctic air masses sweeping through the east coast...and the potential for snow storms from 'Alberta Clipper' and Miller 'A' storms.

FEB:  HIGH pressure retrogrades to a -NAO-east position centered over Iceland.  LOW pressure deviations off the Canadian Maritime provinces supports the continued flow of arctic air masses into the eastern CONUS from the vicinity of Hudson Bay...and cold air damming.

Deviations near the Aleutian LOW weaken and split...with one action center moving to the Gulf of Alaska.

MAR:  Expansive LOW pressure deviations span much of the eastern Pacific.  HIGH pressure over eastern Alaska suggests the stream of arctic air shifts toward the western NOAM. 

JAN/s storm track through the Mediterranean is replaced by HIGH pressure deviations suggesting an end to the persistently negative Northern Annular modes of late.

Winter '09 / '10 - Snow Covers All of England

Snow covers most...if not all...of England...as shown by this image taken by NASA.

The BBC reports widespread 6 - 12" snowfalls in recent days have left much of what's left of the British Empire under a blanket of deep snow.

Unusually cold temperatures have also been observed in a country unaccustomed to extended spells of frigid winter weather.

Winter '09 / '10 - Snow Storm #2 - Final Results

NEWxSFC Senior forecaster Shillelagh has won this season/s second snowfall forecast contest with a SUMSQ error of 570.6"...a 32% improvement over the average SUMSQ error of 836".  His Z-score was a very strong -1.707.

Shillelagh also placed 1st for 'total absolute error' 47.7" (Z-score:  -1.600) and 2nd for 'average absolute error' with 2.51" per station (19 stations forecast).  He had the lowest station errors @BTV...JFK and perfect forecasts @ABE...EWR.

Congratulations Shillelagh!



2nd Place: millersville_bauers* (SUMSQ error: 663.9"; Z-score: -1.107)
3rd Place: Raven (721.6"; -0.736)
Honorable Mention: Dryslot* (735.4; -0.647)

*Rookie

Full forecast verification...storm summary...and final results at the Contest web site here.

Winter '09 / '10 - Snow Storm #2 - Preliminary Verification

Preliminary storm-total snowfalls for Saturday and Sunday from CDUS41...PNS...and CF6 bulletins.

No specific report for HYA.  Interpolated between Chatham (5") and Marston Mills (3.5") from BOX PNS bulletin.

Six new daily records.

SAT...02-JAN-10
CAR - 8.5" (5.8"; 1972)
BGR - 12.1" (9.1"; 1995)
BTV - 19" (7.5"; 1947)
ISP - 3" (1"; 1987)

SUN...03-JAN-10
BTV - 16.4" (7.7"; 1996)
ISP - 2.1" (0.9"; 1988)

Please report errors and a link to the correct data in Comments.

Final results and storm summary Tuesday evening.

Winter '09 / '10 - Snow Storm #2 - The Forecasts

17 entries...including four Rookies...two Interns...one Journeyman...and 10 Senior  forecasters issued 239 station forecasts for this winter/s second contest snow storm.

Forecasts are ranked by storm total precipitation (STP) in ascending order. Blue (red) values are in the 25th (75th) percentile.

Forecasts at the Contest web site.

Consensus for a northern New England event.

Northern annular modes still well below zero providing well-chilled air masses for dendrite production.  Not the typical NE CONUS snow storm morphology where westerlies amplify and long-wave length shortens...evidenced by flat PNA.

Surface LOW forecast to retro-grade and stall in the Gulf of Maine during next 24 hours...which will likely create a tight baroclinic zone and strong forcing from coastal frontogenesis.

Verification period ends 11:59 PM EST SUN 03-JAN-10.
Preliminary storm-total snowfall totals will be posted the evening of MON 04-JAN-10.

Winter '09 / '10 - Snow Storm #2 - RAW FORECASTS

RAW FORECASTS here

 

All forecasts at the Contest web site and summary statistics at the web log will be posted NLT SAT evening.