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

Winter '09 / '10 - Pig Spleens as Predictors

Norbert Schulz - North Dakota pig farmer:

“It is a bad winter... It’s going to turn real nasty.
“In March it looks even worse than it does (in January)...”

"Mr. Schulz uses the width and height of pig spleens to determine if the up-coming winter will be mild and dry or cold and snowy.

"His outlook this year: buy a new shovel."

More ...

Winter '09 / '10 - Quasi-biennial Oscillation - October

-11.70.

A stronger negative value was expected b/c the cycle is five months into its easterly phase.

1991 continues to be the best YTD-analog...followed by 1986...1981...2000...and 1967.  Note its close fit...including the slight upturn through NOV before resuming its decline into spring.

Other 1991 Teleconnections

Strong +ENSO...as measured by MEI...was in excess of +1.5 and reached a max value of +2.248 during spring 1992.  The analog year is the highest-ranked of those matching the top-5 QBO years.

PDO was weakly positive during the winter...dipping close to zero in JAN before turning strongly positive by mid-spring.  It/s the fourth ranked analog.

1991 is the top analog for AO and 4th for NAO.  AO was above zero NOV through MAR...and above +1 DEC and FEB.  Similar tale for NAO...altho JAN/s dip to -0.13 did little to affect the winter/s +0.568 index average.

Sunspots for the period D-J-F-M totaled 576...not a good match for this year/s extreme minima values.

The two tables show the top-5 analog years for QBO.  The top table displays the rank of the corresponding years for other teleconnection indexes, i.e., the 1991 PDO is ranked fourth of all PDO analog years.  The 'Total' column sums all 'rank' values for the analog year.  Low score wins with this decision analysis scheme.  North American snow cover (NA SN) is not included in the scoring b/c data are not available for all analog years.

The bottom table assigns a score relative to all rankings in the same column and assumes every column carries equal weight.  Further refinement to this decision analysis table would assign relative weights to each teleconnection index.  MEI might be weighted 35% and the contribution from sun spots set to 10%.

Note the 1991 PDO is ranked 1st among the other PDO years and has the top score of 1.  The 1991 'Sun Spots' has a low score of 0.10 b/c more sun spots are not associated with colder winters.  1986 has the lowest sun spot count and is scored 1.

1991 QBO has the highest total score of 4.01.  Its score is more than twice as high as the second best analog year 1986...50% higher than 2000...and a strong choice when paired with other teleconnection indexes.

The winter of 1991 produced much below normal snowfall in the mid-Atlantic and southern New England...as is typical for QBO-east and +ENSO winters.

Richmond...VA - 0.9"

DC - 6.6"
Baltimore...MD - 4.1"
Philadelphia...PA - 4.7"
NYC - 12.6"
Binghamtom...NY - 56"
Boston...MA - 19.1"
Concord...NH - 33.6"

Previous QBO post here.

Winter '09 / '10 - NHEMI Snowcover - October

Snow cover over-spread EURASIA rapidly in October...just as it does every year.

NHEMI snow cover is above normal...a somewhat common phenomenon this decade.  Recovery was rapid...after falling ~2% below normal seven or so days into the month.

Snow cover anomaly is over land areas between 35°N and 55°N is currently +6%.

Good autumn snow cover over EURASIA plays an important role in defining winter's character. It perturbs the troposphere in such a way as to weaken the polar vortex (PV).  Arctic air masses are better able to drain into lower latitudes when the PV is weak. The PV is also weaker when the QBO is east...as it will be this winter.  More about EURASIAN snowcover/s predictive role in winter/s wx here.

The combination of rich snow cover in EURASIA and QBO-east could provide the impetus for hi-latitude blocking and a persistently negative state of the northern annular oscillations known as the Arctic Oscillation and the North American Oscillation... which favors above-normal season-total snowfall in the NE and mid-Atlantic regions.  +ENSO-related +PNA and an active lo-latitude / southern-tier storm track should provide ample opportunity for phasing and strong Miller-A cyclogenesis along the eastern seaboard.

More global snowcover charts @ FSU...NOAA...and Rutgers

Winter '09 / '10 - SOI - October

-14.7 and falling!

October registers a rather robust value compared to historical values for the month (data) and a sharp decline from September (+3.9).  Last month's SOI is almost two standard deviations (2STD = -19.5) below the period of record normal. 

The Southern Oscillation index (SOI) has been oscillating about 0 since early spring...in contrast to Multivariate ENSO Index (MEI) which has been bullish on +ENSO during the same period.

With the addition of October's SOI...the 'Top-5' analog years (using a least-squares and coefficient of determination method) are...

1 - 2001 (also top-ranked analog year for NHEMI snow cover and 4th for NOAM snow cover)

2 - 1984 (also 5th rank for NOAM snow cover)

3 - 1999 (also 3rd rank for NOAM snow cover and 5th rank for NAO)

4 - 1963

5 - 1967

SOI turned positive during the '01 / '02 winter.  Not a good match given the widespread expectation for a moderate +ENSO event.

1984 would be a slightly better analog.  QBO was east...as will be the case this winter; however...MEI indicated -ENSO conditions.

1999 was a moderate -ENSO winter.

1963 has a good association with MEI...which was moderate +ENSO.  QBO was west and  PDO negative.

1967 was not quite a moderate -ENSO winter.

Not a lot of corroborating support for choosing SOI as a leading indicator for the upcoming winter.