Winter '09 / '10 - Do Different Flavors of +ENSO Affect BWI Snowfall?

"Looking back at past winters since 1950, approximately 17 were influenced by an El Niño episode.

"Seasonal snowfall averaged above normal for weak and moderate El Niño winters while below normal for strong El Niño episodes."

 - El Niño and DC/Baltimore Winters (WFO LWX - NOV-09)

Judging from the LWX chart...those conclusions would appear reasonable and true.  The lime green column is tallest of them all.  The red column is below climo.

Frank Royance...quoting LWX 'Warning Coordination' meteorologist Chris Strong in his Maryland Wx blog...

"With moderate strength El Nino's (sic) [like this one] we have statistically the greatest chance of above-normal snowfall."

"What they're saying is that not all El Niño winters are alike for the mid-Atlantic states. Some will be snowy; some not. Here's how they tend to break down, according to Klein:

"On average, weak El Niño winters bring below-average temperatures and below-average precipitation. Not generally conducive to lots of snow.

"Strong El Ninos, on average, bring us above-normal temperatures and precipitation. The cold air tends to remain well to our north, so most of the precipitation falls as rain rather than snow."

Sadly..no.

The LWX analysis lacks any significance testing to determine whether the average season-total snowfall for the various +ENSO states are statistically different from each other or climatology (1971 - 2000) or the period-of-record since 1950.

Bottom line up-front:  BS.  Despite appearances...they are not different.  There is no statistically significant difference...between average season-total snowfall observed during weak...moderate...or strong +ENSO winters when compared to each other nor to the period-of-record since 1950 or climatology (1971 - 2000).

The study's conclusions about the probability of observing more or less season-total snowfall relative to 'normal' is unsupported at the 95% confidence level.  There is weak evidence...at the 90% confidence level...to conclude 'moderate' +ENSO winters observed more snowfall...on average...compared to climatology (1971 - 2000) and the period-of-record beginning in 1950...which is pretty weak tea.

Data and analysis after the jump.

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Winter '09 / '10 - Outlook - Eric Horst

Eric Horst - Director...Wx Information Center  @Millersville University of Pennsylvania

"...we could see about 36 inches of snow this year, about 10 inches (ed:  ~40%) above normal, and about two to three times more than we've had in the last two winters combined.

"...I am anticipating...a greater frequency of coastal storms...

"That can have a notable effect on snowfall here. For example, last year...one nor'easter, on March 2...gave us 6 inches of snow.

"This winter, ...will be watching that southern storm track...  'That may mean four, five, six storms take that track.  It doesn't mean we get hammered four, five, six times, but there is going to be the opportunity to develop these.

"The only caveat...if the waters in the equatorial Pacific cool (sic) too much, we could have a "super El Niño" winter, which would be more wet than white."

More...

Eric Horst's '08 / '09 outlook here.

Winter '09 / '10 - WSI - Europe

Todd Crawford - WSI seasonal forecaster: 

"The combination of the current El Nino event, abundant Eurasian snow cover, and a favourable pattern of ocean temperatures in the Atlantic Ocean suggest that this winter will be a cold one across much of northern and central Europe, especially after the New Year...

 

"WSI also expects below normal temperatures during the three-month period in eastern and south-central parts of the United States..."

More...

Winter '09 / '10 - ENSO Rising

"This image was created with data collected OSTM/Jason 2 during a 10-day period centered on November 1, 2009. Red and white areas in the central and eastern equatorial Pacific were 100 to 180 millimeters (4 to 7 inches) above normal. In the western equatorial Pacific, blue and purple areas show where sea levels were between 80 and 150 millimeters (3 and 6 inches) below normal.

"Sea surface height is an indication of temperature because water expands slightly as it warms and contracts as it cools. The elevated sea levels in the central and eastern Pacific are equivalent to sea surface temperatures more than one to two degrees Celsius above normal (two to four degrees Fahrenheit)."

 More...

NASA image by the Jet Propulsion Laboratory Ocean Surface Topography Team

Winter '09 / '10 - Heavy Snow Across China

"At least 38 people have died in some of the worst snows to hit northern China in decades...

"Major highways in north China have been shut down, leaving at least 10,000 vehicles and up to 30,000 people stranded on roads in Shanxi alone..."

"The 19-inch thick snow that fell in Hebei province's capital of Shijiazhuang was the heaviest ever recorded since 1955."

"Parts of southern China are now suffering low temperatures and snow, while almost all of northwestern China can expect continuing low temperatures and gales. Local governments are taking practical measures to cope with the cold weather and heavy snow.

"Meanwhile, parts of northwestern China, including Gansu and Shaanxi, are suffering a new round of snow storms, with temperatures in some areas dropping sharply by 20 degrees Celsius (36°F)."

"Early and heavy snow storms in north China have killed 32 people, destroyed nearly 300,000 hectares of winter crops, and caused nearly 7 billion yuan (about one billion US dollars)...

"More than 15,000 buildings collapsed..."

More about the 12-NOV event here...here...here...and here.

Image courtesy 'Image of the Day' from the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite.

Winter '09 / '10 - ENSO Outlook - November

From The International Research Institute for
Climate and Society (IRI)

"By mid-November 2009, the NINO3.4 SST anomaly index had risen to values indicative of the moderate El Niño category. Up until recently, the event had maintainined (sic) only a weak magnitude, but strong and persistent westerly wind anomalies during September, and especially those during October, substantially increased the SST anomalies in the central and eastern equatorial Pacific.

"Those wind anomalies also had a substantial impact on the sub-surface ocean, deepening the thermocline. This could allow for further growth and will certainly provide several months of persistence to the current event. The wind anomalies in the western Pacific have become easterly since early November, suggesting that much of the rrecent (sic) wind anomalies are due to passage of a very strong MJO, or intraseasonal (sic) variability.El Niño conditions are expected to persist through the end of the calendar year and possibly a few additional months.

"Out of a large set of dynamical and statistical forecast models, nearly all indicate maintenance of El Niño conditions during the Nov-Dec-Jan season currently in progress. Overall, based on model forecasts and current observations of the ocean surface and subsurface, for the coming Dec-Jan-Feb season the probability for El Niño conditions is estimated at 96%, and for ENSO-neutral conditions approximately 3%. The estimated strength of this El Niño event now appears moderate, and the most likely period of duration is through early 2010."

Recent performance trends show the models respond too quickly (slowly) when temperature anomalies are rising (falling).

Winter '09 / '10 - National Wx Circus - Final Call

The Climate Prediction Center issued its final winter outlook (0.5 month long-lead) today.  Essentially unchanged from last month's outlook.

Cooler in the SE...warmer in the Northern and Central Plains...Northern Rockies...and Alaska.

Above normal precipitation along the southern tier of states ...consistant with typical +ENSO storm track.

+ENSO has reached moderate strength in recent weeks.  Latest Region 3.4 weekly temperature anomaly is  1.7°C.  The 12-week moving average is 1.06°C.

The CPC's forecast for below normal temperatures in the SE suggests a winter where the average Arctic Oscillation below zero.

Winter '09 / '10 - Early Season Stratospheric Warming

Joe D'Aleo has a post up at ICECAP about an incipient warming event @50 and 30 mb that may herald an early start to winter.

He notes the current spike in temperature above the long-term average and draws upon an historical analog where the Arctic Oscillation (AO) collapsed.

Not much support found for warming in today/s 10 mb height field.  There is a small broad region of -45°C air over the northern Canada and NE Siberia.

Stratospheric forecasts from the ECMWF show a short-lived transient flow reversal on the 21st...but no warming in the height - latitude chart (not shown).  The closest to a bifurcated flow over the pole is projected for today...which the analysis from U of Wyoming indicates did occur.

NCEP GFS forecast offers a decidedly different solution @144 hours (NOV 23) and 240-hours (NOV 27). 

D'Aleo concludes with "(i)f this warming in the stratospheric persists, look for a rapid cooling to begin around Thanksgiving."

More from ICECAP (.pdf)...

50mb time-height cross section courtesy CPC Global Temperature Time Series
10mb planar temperature forecast courtesy CPC Stratospheric Analyses and Forecasts
Zonal wind anomalies courtesy CPC Stratosphere-Troposphere Monitoring

Amazing Snow

Gorgeous snow pr0n from all over the world.

Well worth a visit.

Amazing Snow

Winter '09 / '10 - European Snow Outlook - AccuWeather

Bastardi on Europe