Meteorological winter officially begins on December 1, but winter has begun a week early across much of North America, thanks to a significant cold blast that has broken dozens of daily low temperature records across much of western Canada and the Western U.S. Sheridan, Wyoming set a new record for the date this morning with -17°F, and Oakland California had its coldest November 24th with a reading of 34°F this morning. The cold blast is expected to be short-lived, though, with near-average conditions returning by the weekend. The long-range 1 - 2 week forecasts from the GFS and ECMWF models do not show the jet stream getting "stuck" in place for the beginning of meteorological winter next week, and it appears that the first two weeks of winter will be rather ordinary.
Figure 1. Forecast temperature and precipitation for the U.S. for the upcoming winter, as predicted by NOAA.
Latest winter forecast from NOAA
We currently have moderate La Niña conditions over the tropical Pacific ocean, which means that a large region of cooler than average waters exists along the Equator from the coast of South America to the Date Line. Cooler than average waters in this location tend to deflect the jet stream such that the Pacific Northwest experiences cooler and wetter winters than average, while the southern U.S. sees warmer and drier winter weather. NOAA's forecast for the upcoming winter issued on October 21 calls for a typical La Niña winter over the U.S.--warm and dry over the southern portion of the country, cool and wet over the Pacific Northwest, warmer and wetter than average over the Ohio Valley, and near average over the remainder of the country. According to NOAA's latest La Niña discussion, La Niña is expected to remain solidly entrenched throughout the coming winter and into spring.
Figure 2. Observed temperature and precipitation departures from average for the last three winters with a La Niña in the "moderate" or "strong" category. The current La Niña is right at the borderline between "moderate" and "strong." The anomaly patterns from the past three La Niña winters were dominated by the winter of 1999 - 2000, which was the warmest winter in U.S. history, and 1998 - 1999, which was the 2nd warmest in U.S. history. Image credit: NOAA/ESRL.
What happened during the last three La Niña winters?
The last three winters with moderate to strong La Niña conditions occurred in 2007 - 2008, 1999 - 2000, and 1998 - 1999. These winters were extremely variable. The most recent La Niña winter, in 2007 - 2008, was near average in temperature and precipitation; the other two winters were the two warmest winters in U.S. history. The winter of 1998 - 1999 set a world record for the greatest seasonal snowfall in history, when a seemingly endless parade of winter storms across the Pacific Northwest left an astonishing 1,140 inches (95 feet) of snow at Mt. Baker in northwestern Washington. It's worth noting that two of these three La Niña winters (2007 - 2008 and 1998 - 1999) saw record levels of tornado activity. Of the three winters, I believe that the winter of 2007 - 2008 may be the best historical analogue for the coming winter, since Arctic sea ice loss, which can significantly affect winter weather, was most similar to the conditions observed this year.
A look back at the winter of 2007 - 2008
The La Niña winter of 2007 - 2008 started slowly, but ended up piling up quite a bit of snow across much of the U.S. New York experienced its wettest winter on record, and Colorado, Connecticut, Pennsylvania, and Vermont had their second wettest winter on record. As is typical during a La Niña winter, Texas was drier than normal, but the rest of the south had near-average precipitation.
According to The Northern Tier Rules: The 2007-2008 Snow Report by David Robinson, Weatherwise, Mar-Apr 2009, eleven major cities reported more than 125 percent of average snowfall. This compares with only three in 2006-2007, and was the most since thirteen cities in 2003-2004.
Record high snow seasons occurred in Madison, Wisconsin (101.4 inches, previous record of 76.1 inches in 1978-1979); Youngstown, Ohio (102.8 inches, previous record of 90.2 inches in 2005-2006); and Caribou, Maine (197.8 inches, previous record of 181.1 inches in 1954-1955). Two stations came very close to establishing seasonal seasonal records; Spokane, Washington, 92.6", 0.9" below the 1949-1950 record, and Flint, Michigan, 82.8", just 0.1" below the record set in 1974-1975.
Figure 3. Snowfall totals for the winter of 2007 - 2008. Image credit: The Northern Tier Rules: The 2007-2008 Snow Report by David Robinson, Weatherwise, Mar-Apr 2009.
Wildcard number 1: What will the NAO do?
The North Atlantic Oscillation (NAO) is a climate pattern in the North Atlantic Ocean of fluctuations in the difference of sea-level pressure between the Icelandic Low and the Azores High. It is one of oldest known climate oscillations--seafaring Scandinavians described the pattern several centuries ago. Through east-west oscillation motions of the Icelandic Low and the Azores High,the NAO controls the strength and direction of westerly winds and storm tracks across the North Atlantic. A large difference in the pressure between Iceland and the Azores (positive NAO) leads to increased westerly winds and mild and wet winters in Europe. Positive NAO conditions also cause the Icelandic Low to draw a stronger south-westerly flow of air over eastern North America, preventing Arctic air from plunging southward. In contrast, if the difference in sea-level pressure between Iceland and the Azores is small (negative NAO), westerly winds are suppressed, allowing Arctic air to spill southwards into eastern North America more readily. Negative NAO winters tend to bring cold winters to Europe, and the prevailing storm track moves south towards the Mediterranean Sea. This brings increased storm activity and rainfall to southern Europe and North Africa.
The winter of 2009 - 2010 had the most extreme negative NAO since record keeping began in 1950. The NAO index was -1.67, beating the previous record of -1.47 set in the winter of 1962 - 1963. The record negative NAO was responsible for unusual cold weather and snows over Eastern North America and Europe, and resulted in an upside-down winter: coldest in 25 years in the U.S., and warmest on record in Canada, with snow needing to be trucked in for the Winter Olympics in Vancouver. This "Warm Arctic-Cold Continents pattern" had occurred previously only three times in the past 160 years. If a strong negative NAO establishes itself this winter, we could have a winter like 1995 - 1996, which featured a weak La Niña and a strongly negative NAO. That winter featured many cold air outbreaks across the Eastern U.S., resulting in fifteen major cities setting new all-time seasonal snowfall total, including 75.6" at New York City's Central Park. Unfortunately, the NAO is not predictable more than about two weeks in advance.
Wildcard number 2: How will Arctic sea ice loss affect the winter?
NOAA issued their annual Arctic Report Card last month, and discussed the fact that recent record sea ice loss in the summer in the Arctic is having major impacts on winter weather over the continents of the Northern Hemisphere. The Report Card states, "There continues to be significant excess heat storage in the Arctic Ocean at the end of summer due to continued near-record sea ice loss. There is evidence that the effect of higher air temperatures in the lower Arctic atmosphere in fall is contributing to changes in the atmospheric circulation in both the Arctic and northern mid-latitudes. Winter 2009-2010 showed a new connectivity between mid-latitude extreme cold and snowy weather events and changes in the wind patterns of the Arctic; the so-called Warm Arctic-Cold Continents pattern...With future loss of sea ice, such conditions as winter 2009-2010 could happen more often. Thus we have a potential climate change paradox. Rather than a general warming everywhere, the loss of sea ice and a warmer Arctic can increase the impact of the Arctic on lower latitudes, bringing colder weather to southern locations." As a specific example of what the Report Card is talking about, Francis et al. (2009) found that during 1979 - 2006, years that had unusually low summertime Arctic sea ice had a 10 - 20% reduction in the temperature difference between the Equator and North Pole. This resulted in a weaker jet stream with slower winds that lasted a full six months, through fall and winter. The weaker jet caused a weaker Aleutian Low and Icelandic Low during the winter, resulting in a more negative North Atlantic Oscillation (NAO), allowing cold air to spill out of the Arctic and into Europe and the Eastern U.S. Thus, Arctic sea ice loss may have been partially responsible for the record negative NAO observed during the winter of 2009 - 2010, and the emergence of the "Warm Arctic-Cold Continents pattern." This pattern is kind of like leaving the refrigerator door ajar--the refrigerator warm up, but all the cold air spills out into the house. If the Arctic Report Card is right, we'll be seeing more of this pattern during coming winters--possibly even during the winter of 2010 - 2011.
Summary
I'm often asked by friends and neighbors what my forecast for the coming winter is. My reply is usually, "Flip a coin. We don't have the capability to make very skillful predictions of the coming winter." I'll share with you my hunch for this winter, though--we are due for a rather ordinary La Niña winter like we had in 2007 - 2008. After a year of some extraordinary extreme weather, we are overdue for a relatively quiet season or two of weather.
For more information
Golden Gate Weather has a nice set of imagery showing historic La Niña winter impacts, based on whether it was a "weak", "moderate", or "strong" event.
Francis, J. A., W. Chan, D. J. Leathers, J. R. Miller, and D. E. Veron, 2009: Winter northern hemisphere weather patterns remember summer Arctic sea-ice extent. Geophys. Res. Lett., 36, L07503, doi:10.1029/2009GL037274.
Honda, M., J. Inoue, and S. Yamane, 2009: Influence of low Arctic sea-ice minima on anomalously cold Eurasian winters. Geophys. Res. Lett., 36, L08707, doi:10.1029/2008GL037079.
Overland, J. E., and M. Wang, 2010: Large-scale atmospheric circulation changes associated with the recent loss of Arctic sea ice. Tellus, 62A, 1.9.
Petoukhov, V., and V. Semenov, 2010: A link between reduced Barents-Kara sea ice and cold winter extremes over northern continents. J. Geophys. Res.-Atmos., ISSN 0148-0227.
Seager, R., Y. Kushnir, J. Nakamura, M. Ting, and N. Naik (2010), Northern Hemisphere winter snow anomalies: ENSO, NAO and the winter of 2009/10, Geophys. Res. Lett., 37, L14703, doi:10.1029/2010GL043830.
Next post
Thanksgiving break is at hand, and I plan to spend it enjoying family and friends, eating far too much delicious food, and watching the invincible juggernaut that is my favorite football team, the Detroit Lions, demolish yet another hapless opponent on Thanksgiving Day (not!) I'm also looking forward to seeing the season's first snowflakes here in Michigan on Friday--winter has been late arriving here this year. I'll be back with a new post on Monday. Have a great Thanksgiving, everyone!
Jeff Masters
The snow just keeps on coming.
Blizzard made strange designs on Boone Creek, these are around 6 feet high.
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Its Snowing...still
Arctic Front on its way through Texas.
Yikes... ;-)
I think we may be seeing a real impact of Global Warming, if these patterns are repeated, especially as the Pacific has entered a different phase of the ESNO. I think the Winter of 2011, the climatological beginning date for which is 1 December, may bring some even more interesting weather than that seen last winter. Here's an article which discusses the Winter of 2010 as seen from a European perspective:
http://en.wikipedia.org/wiki/Winter_of_2009-10_in_Europe
Also there was this:
http://www.timesonline.co.uk/tol/news/weather/article6982249.ece
Got woke up at 530 am from our tornado sirens going off, supposed to snow tonight. gotta love it
Nothing says Happy Thanksgiving like that lol
Lol yeah, for a minute it looked like a tornado was gonna develop right over my town
Happy Thanksgiving!
Have a good holiday everyone! Hey, hydrus, just to let you know, turkey tastes much better than dinosaur meat. Used to take weeks to defrost those things. Stay happy and healthy everybody.
Thought you would get a kick out of this, hydrus.
Link
Happy Thanksgiving to all! Enjoy the day.
A minor quibble for you. I suppose you aren't concerned with climate, only weather. As Dr. Masters noted above, meteorological winter starts 1 December. Now, given the fact that the calendar is an arbitrary division of the solar year, it's rather obvious that it is more appropriate to speak of that date as being the beginning of the Winter of 2011, especially since 2 of the 3 months included in this definition are actually in the calendar year 2011. Of course, the "official" start of Winter is said to be the Winter Solstice, which may be a good match to European climate, given the effects of the Atlantic Ocean, but that date is a bit late for the US, IMHO.
While we are at it, please also consider the fact that low pressure in a fluid flow can not be said to cause the flow. That's because a fluid, such as the atmosphere, can not exert a tension force, only a pressure force. In the atmosphere, gravity does the pulling. My favorite analogy is trying to push on a stretched rope, which can't be done as a rope transfers force via tension. There are also viscous forces due to the flow of one portion of a fluid across a surface or across a different layer. With this perspective, I take exception to Dr. Master's statement above:
"Positive NAO conditions also cause the Icelandic Low to draw a stronger south-westerly flow of air over eastern North America, preventing Arctic air from plunging southward...."
I think that the pressure differences seen in the NAO index are the RESULT of the flows, not the CAUSE. If the low pressure actually did "draw" the air from one place to another, the low would rapidly be filled in, would it not? My understanding is that a more negative NAO just tells one that the storm tracks did not pass over Iceland, but took a different path, so the pressure at the surface averaged over a period of time appears higher.
Which came first, the chicken or the egg???
Thanks Grothar, you too!
This is true. One could remedy the statement by saying that "The extreme hemispheric pattern associated with the record negative NAO was responsible for unusual cold weather and snows over Eastern North America and Europe..."
The Winter of 1620-'21
"Nearly all historians describe the winter of 1620-'21 as mild, though the season began with harsh weather early in December just at the time the Pilgrims were exploring the unknown land."
Was that a La Niña year?
Orca - What's that white stuff on the ground in your photos? That can't be snow, isn't a little early for that?
Don't wish me that crap! lol, I for one realize that low pressure producing rain is needed to enjoy all the wildlife and forests that make our planet so amazing. If our barometers were always on the rise everywhere would look like the dang sahara desert.
Dang wimpy city people cry about rain and low pressure, but low pressure and rain is what makes our planet amazing. Jungles, forests, and vast amounts of wildlife, all would not exist if it weren't for rain.
Plus, if you don't like storms, why the heck would you post in a weather blog? I would hate living in very dry area of the world. I love rain and thunderstorms.
Again, let me try to be clear. According to my understanding of climate dating, which I attempted to explain above, Winter 2010 began in December 2009 and ended in February 2010. It really doesn't matter what terminology one uses, but, the story from the Times I linked to goes into more detail about last Winter. This Winter is starting out with a bang as the old saying goes and the conditions over the North of Europe and Britain look a lot like those last Winter.
Time will tell whether this year will be a repeat of last year. If so and if future years are similar, it's possible we have tipped into a new Earth climate. The Earth has been in a glacial period for about 3 million years. We are enjoying an interglacial, the last of which didn't span as much time as this one. The last one was slightly warmer than the recent past, which suggests that the end of that interglacial might have been associated with the warmer conditions. Have fun watching the weather...
Tornado Warning
TORNADO WARNING
TNC071-109-252300-
/O.NEW.KMEG.TO.W.0107.101125T2214Z-101125T2300Z/
BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE MEMPHIS TN
414 PM CST THU NOV 25 2010
THE NATIONAL WEATHER SERVICE IN MEMPHIS HAS ISSUED A
* TORNADO WARNING FOR...
HARDIN COUNTY IN SOUTHWEST TENNESSEE...
SOUTHEASTERN MCNAIRY COUNTY IN SOUTHWEST TENNESSEE...
* UNTIL 500 PM CST
* AT 414 PM CST...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
SEVERE THUNDERSTORM PRODUCING A TORNADO 9 MILES SOUTHWEST OF
SHILOH...OR 8 MILES NORTH OF CORINTH...MOVING NORTHEAST AT 40 MPH.
STORM SPOTTERS AND EMERGENCY MANAGEMENT REPORT A FUNNEL CLOUD
LOWERING TOWARDS THE GROUND. TAKE COVER IMMEDIATELY.
* LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO SAVANNAH
AND PICKWICK LANDING STATE PARK.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
.THE SAFEST PLACE TO BE DURING A TORNADO IS IN A STORM SHELTER. IF NO
STORM SHELTER IS AVAILABLE...SEEK SHELTER ON THE LOWEST FLOOR OF THE
BUILDING IN AN INTERIOR HALLWAY OR ROOM SUCH AS A CLOSET. USE
BLANKETS OR PILLOWS TO COVER YOUR BODY AND ALWAYS STAY AWAY FROM
WINDOWS.
IF IN MOBILE HOMES OR VEHICLES...EVACUATE THEM AND GET INSIDE A
SUBSTANTIAL SHELTER. IF NO SHELTER IS AVAILABLE...LIE FLAT IN THE
NEAREST DITCH OR OTHER LOW SPOT AND COVER YOUR HEAD WITH YOUR HANDS.
&&
LAT...LON 3509 8798 3500 8850 3500 8853 3510 8863
3542 8823
TIME...MOT...LOC 2214Z 233DEG 36KT 3508 8847
$$
I had my storms this morning, had a tornado warning at 530 a.m. rain will transition to snow in a few hours :pp crazy weather
SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE MEMPHIS TN
430 PM CST THU NOV 25 2010
TNC071-252300-
/O.CON.KMEG.TO.W.0107.000000T0000Z-101125T2300Z/
HARDIN TN-
430 PM CST THU NOV 25 2010
...A TORNADO WARNING REMAINS IN EFFECT UNTIL 500 PM CST FOR HARDIN
COUNTY...
AT 428 PM CST...TRAINED WEATHER SPOTTERS REPORTED A FUNNEL CLOUDS
LOWERING TOWARDS THE GROUND AS THE STORM PASSED NEAR GUYS IN MCNAIRY
COUNTY. NATIONAL WEATHER SERVICE DOPPLER RADAR ALSO INDICATES
ROTATION WITH THIS STORM. THIS TORNADO WAS LOCATED NEAR PITTSBURG
LANDING...OR 8 MILES NORTHWEST OF PICKWICK LANDING STATE
PARK...MOVING NORTHEAST AT 40 MPH.
LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO CRUMP...
SALTILLO...SAVANNAH...FIVE FORKS...CERRO GORDO...BUCKTOWN...
PHILLIPS...WALKERTOWN...CENTER STAR...MADDOX...LOWRYVILLE...BRUTON
BRANCH...SIBLEY AND COFFEE LANDING.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
THE SAFEST PLACE TO BE DURING A TORNADO IS IN A STORM SHELTER. IF NO
STORM SHELTER IS AVAILABLE...SEEK SHELTER ON THE LOWEST FLOOR OF THE
BUILDING IN AN INTERIOR HALLWAY OR ROOM SUCH AS A CLOSET. USE
BLANKETS OR PILLOWS TO COVER YOUR BODY AND ALWAYS STAY AWAY FROM
WINDOWS.
IF IN MOBILE HOMES OR VEHICLES...EVACUATE THEM AND GET INSIDE A
SUBSTANTIAL SHELTER. IF NO SHELTER IS AVAILABLE...LIE FLAT IN THE
NEAREST DITCH OR OTHER LOW SPOT AND COVER YOUR HEAD WITH YOUR HANDS.
.A SEVERE THUNDERSTORM WATCH ALSO REMAINS IN EFFECT FOR THE ALERT
AREA.
&&
LAT...LON 3509 8798 3505 8838 3521 8837 3542 8823
TIME...MOT...LOC 2228Z 237DEG 37KT 3514 8829
$$
haha yeah it's been windy too
here is the tornado warning from this morning, I live in Washington, Indiana:
337
WFUS53 KIND 251025
TORIND
INC027-101-251100-
/O.NEW.KIND.TO.W.0060.101125T1025Z-101125T1100Z/
BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
525 AM EST THU NOV 25 2010
THE NATIONAL WEATHER SERVICE IN INDIANAPOLIS HAS ISSUED A
* TORNADO WARNING FOR...
SOUTHERN DAVIESS COUNTY IN SOUTHWEST INDIANA...
WESTERN MARTIN COUNTY IN SOUTHWEST INDIANA...
* UNTIL 600 AM EST
* AT 523 AM EST...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO. THIS DANGEROUS
STORM WAS LOCATED NEAR WASHINGTON...OR 11 MILES NORTHEAST OF
PETERSBURG...AND MOVING EAST AT 65 MPH.
* THIS DANGEROUS STORM WILL BE NEAR...
CANNELBURG...MONTGOMERY AND ALFORDSVILLE AROUND 530 AM EST...
LOOGOOTEE AND WEST BOGGS LAKE AROUND 535 AM EST...
BURNS CITY AROUND 540 AM EST...
PRECAUTIONARY/PREPAREDNESS ACTIONS...
TAKE COVER NOW. MOVE TO AN INTERIOR ROOM ON THE LOWEST FLOOR OF A
STURDY BUILDING. AVOID WINDOWS. IF IN A MOBILE HOME...A VEHICLE OR
OUTDOORS...MOVE TO THE CLOSEST SUBSTANTIAL SHELTER AND PROTECT
YOURSELF FROM FLYING DEBRIS.
THIS LINE OF THUNDERSTORMS IS CAPABLE OF PRODUCING TORNADOES AND
WIDESPREAD SIGNIFICANT WIND DAMAGE. DO NOT WAIT TO SEE OR HEAR THE
TORNADO. FOR YOUR PROTECTION MOVE TO AN INTERIOR ROOM ON THE LOWEST
FLOOR OF YOUR HOME OR BUSINESS.
LAT...LON 3853 8717 3855 8721 3864 8725 3865 8725
3868 8727 3885 8688 3857 8676 3853 8711
3853 8713 3852 8717
TIME...MOT...LOC 1025Z 250DEG 54KT 3862 8712
Happy Thanksgiving to you too!
This next system looks like it could be pretty impressive as well, just not sure yet.
Did you notice the storm speed from this morning? 65mph
yeah, it was right along the warm front
Viewing: 101 - 151
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