The U.S. and European cold blast: blame the NAO

By: Dr. Jeff Masters , 4:00 PM GMT on January 07, 2010

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The Deep South shivered through another frigid morning today, with low temperature records crumbling again over much of Florida. Lakeland hit 27°F, smashing the old record of 34°F; Melbourne hit 28°F, eclipsing the old record of 32°F; and West Palm Beach bottomed out at 37°F, besting the old record of 38°F. The cold wave is being driven by an unusual sharp and persistent kink in the jet stream that is being blocked from moving by a strong ridge of high pressure over Greenland. As a result, an exceptionally strong surface high pressure of 1055 mb over the North Central U.S. is pushing large amounts of cold, Arctic air southwards from Canada. No coldest January temperature records have been set yet from the cold blast, but the 500 largest U.S. cities have been averaging about 11 new daily low temperature records per day the first five days of January, according to the National Climatic Data Center. The cold will ease Friday in the Deep South, but return with a vengeance Saturday night though Monday morning, as another push of cold air descending from Canada promises to bring a cold wave that will approach the December 1989 and January 1977 cold waves in intensity, and may being some new all-time January low temperature records to the South.

Colder in Florida than Alaska and Greenland
The sharp kink in the jet stream has brought record warm temperatures to a few stations in Alaska and the Pacific Northwest this week, making much of coastal Alaska warmer than Florida. Cold Bay, Alaska, set a record high yesterday of 47°F, after recording a low temperature of 30°F. This made Cold Bay warmer than Pensacola, Florida, which had a high of 47°F and a low of 24°F. In fact, most of Florida--including Jacksonville, Tampa, Melbourne, and Tallahassee--recorded lows at or below the 27°F low recorded in Anchorage, Alaska yesterday. The jet stream kink has also brought temperatures more than 30°F above average to Greenland. The temperature in Narsarsuaq, Greenland at 10am EST today was 46°F, far warmer than most of Florida.


Figure 1. Departure of the surface temperature from average for the first three day of 2010 shows much colder than average conditions were present over the Southeast U.S., much of Europe, and Central Asia. Much warmer than average temperatures were present over the Northwest U.S., Greenland, the Arctic, and Southern Asia. A sharp kink in the jet stream was responsible for the temperature anomaly pattern. Image credit: NOAA/ESRL.

Snow in Florida?
It doesn't snow very often in Florida, and the Wikipedia list of snow events in Florida lists only seven such events over the decade of the 2000s. This weekend's cold wave may be able to generate some snow over isolated regions of Central Florida, though it appears that the odds of this happening are less than 30%. The most widespread snowfall in Florida history occurred on January 19, 1977, when snow fell over much of the state, with flurries as far south as Homestead. Snow flurries also fell on Miami Beach for the only time in recorded history.


Figure 2. North Atlantic Oscillation (NAO) index for September 9, 2009 - January 6, 2010 (black line) and forecast from the GFS model (red lines). The NAO index was strongly negative, near -2.0, for much of December and January. Image credit: NOAA/CPC.

The winter cold blast: blame the North Atlantic Oscillation (NAO)
Why has the winter been so cold over Eastern North America and northern Europe? Well, don't blame El Niño. El Niño winters are rarely this cold. Instead, blame the the North Atlantic Oscillation (NAO). The 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 has seen a very strong negative NAO, causing much of our cold weather over Eastern North America and Europe. The NAO index for the month of December 2009 was -1.93, which is the third lowest NAO index since 1950 for a winter month (December, January, or February). The only winter months with a lower NAO index were February 1978 (-2.20) and January 1963 (-2.12). January 1963 was one of the coldest months on record in the UK and the Eastern U.S.. February 1978 was the coldest February on record for five U.S. states, and featured the historic blizzards in both the U.S. and UK. The NAO so far for January 2010 has continued to stay strongly negative, ranging between -1.5 and -2.1. However, the blocking ridge over Greenland is forecast to weaken next week, allowing the sharp kink in the jet stream to straighten out. This will increase the NAO index to more typical values, allowing a return of more ordinary winter weather to the U.S. and Europe.

Jeff Masters

From The Porch 1 (suzi46)
from our porch view of sunrise this morning..totally different from the 'splendiferous' shots 1-8 taken from the top of our field overlooking the mountains
From The Porch 1
First snow (Rowdyblue)
of winter in South Mississippi.
First snow
Wind blown snow (bikesnapper)
Like sand dunes or Antelope Canyon
Wind blown snow

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Look up regional radar on Wunderground. That shows sleet in broward right now. I am seeing it on my car
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2027. IKE
From Jacksonville,FL....

Statement as of 9:30 am EST on January 9, 2010

... Long lasting cold spell could set new temperature records...

As of today... Saturday January 9th at 9 am... there have been 7
consecutive days with minimum temperatures less than or equal to 32
degrees at Alma Georgia and Gainesville Florida and 6 days at Saint
Simons Island Georgia with the streaks still in tact. The temperature at
Jacksonville last night only reached 34 degrees... ending their streak
of consecutive days at 6.

The most recent event with such long lasting cold temperatures was
in the winter of 2000-2001 when a week long period of sub-freezing
temperatures was seen around the New Year.

With another Arctic airmass over the region the consecutive
number of days with sub-freezing temperatures will last into the
middle of next week for most sites and will likely number between 10
and 12 days. This will likely break historical records at most local
climate sites.

The records for consecutive days with 32 degrees or less at local
climate sites are listed below...

Jacksonville, Florida... 8 days... January 17-24, 1977
Gainesville, Florida... 9 days... December 16-24, 1960
Alma, Georgia... 11 days... December 16-26, 1960
St Simons Island, Georgia... 8 days... December 29 to January 5, 2001
Member Since: June 9, 2005 Posts: 23 Comments: 37860
Its is really sleeting hard and the temp is droping. Its bouncing off everything.
Member Since: August 11, 2008 Posts: 0 Comments: 2315
2025. IKE
Quoting TheMom:
WE GOT SLOP!!!! Bout 9 we were just getting rain and ice pellets then it started having sleet and snow mixed in, now is sleet and rain with occasional ice pellets.


Picture?
Member Since: June 9, 2005 Posts: 23 Comments: 37860
Quoting AwakeInMaryland:
Good Morning, Orca. How are you, sir?
Did South Florida get snow? Is South Florida going to get snow? What did the Chief Say?


Central did.. not sure where they consider "South Florida" to start... from here.. you are all in the deep south... so to me.. that would be the ummm I don't know.. deepest deep south? Zoo only had rain.
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2023. TheMom
WE GOT SLOP!!!! Bout 9 we were just getting rain and ice pellets then it started having sleet and snow mixed in, now is sleet and rain with occasional ice pellets.
Member Since: August 3, 2006 Posts: 5 Comments: 672
Sleet came down this morning, but that's all I saw; however, snow was repoerted in SW Palm Coast.. So close. Overcast right now with some freezing drizzle, God I hope this system budges north one more time so I can get some pictures.
Member Since: July 1, 2008 Posts: 13 Comments: 7423
Good Morning, Orca and everyone. How are you, sir?
Did South Florida get snow? Is South Florida going to get snow? What did the Chief Say?
Member Since: August 19, 2008 Posts: 32 Comments: 1918
2019. eddye
i found some baby sleet in davie florida
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Quoting IKE:
And that's probably about the end of that event.

No storm reports for awhile.



I don't think it's reaching the ground.


Agree with Ike-radar looked like that over Tally this a.m.but nothing at all in the air.
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2016. IKE
Member Since: June 9, 2005 Posts: 23 Comments: 37860
Quoting StormChaser81:
seeing little snow flakes now mixed with sleet


Happy Dance Happy Dance Happy Dance Happy Dance

Umm I mean.. sorry to hear your getting SNOW in the deep south
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seeing little snow flakes now mixed with sleet
Member Since: August 11, 2008 Posts: 0 Comments: 2315
Quoting nrtiwlnvragn:


You never did fix that latent negative feedback loop in "your work", so you thought last summer was hot in BC, well....



Now now..I meant hot in cancun :)
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Sleeting heavy now. Winter Park, FL. 33.9 degrees
Member Since: August 11, 2008 Posts: 0 Comments: 2315
Quoting Orcasystems:
Now that Florida got snow.. I will get KOG to turn off the fans... our work is done :)
Need it to warm up now.... want it really hot for next week :)


You never did fix that latent negative feedback loop in "your work", so you thought last summer was hot in BC, well....

Member Since: September 23, 2005 Posts: 14 Comments: 11274
Woke to heavy sleet at 6:30 am in Merritt Island, woke up the kids and we actually saw a few tiny flakes mixed in with the sleet/rain. Keep looking out the window hoping to see more flakes, but only seeing rain. Currently 36 degrees here.
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2009. chawk
Well today I will for the first time in 20 years have to build a tent over my 20' high mango trees or else lose them tonight. It has had foliage loss due to frost before but never anything below 32f. I'm off to Lowes.
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I don’t think global warming is a very good description of what is happening to the planet. More like climate change, human-induced climate change. And the Earth is not threatened. We are, the erstwhile CO2 spewing inhabitants. Cooling is part of the change. Weird weather is part of the change. And yes, CO2 is released naturally, but not in the quantities humans have increasingly created in the past 200 years.

Then there are the natural cycles we can’t even understand as we really are just beginning to put together a good historical picture. So given all this, it might be prudent to alter our habits to preserve what we have as it is most hospitable for our kind. Ideas like using the northern shipping route when it opens will just lead to more heat, more melt, and who knows maybe we’ll contribute to a mini-ice age.

Majority of climate scientists think something not easily reversible is going on, but even if it is natural, wouldn’t it make sense to stop aggravating it? All of Florida was once under water, naturally. But I sure wouldn’t like to see that happen again—well, unless the Gulf came right up to my backdoor in central Florida. That would be sweet. Our property values could fund our retirement. Hmmmm, maybe I’ll rethink this and contribute something to climate change.
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Here in Altamonte Springs, it started sleeting at about 7 AM (could swear I saw a few flakes too). This then changed to rain with the occasional ice pellet mixed in. I am anxiously waiting for it to change over to snow...here's hoping!
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rain/ice pellets here... 35 degrees....
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hi, 36 degrees feel like 34 in fort myers, maybe an isolated sleet local met said nit down to broward county
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2004. Nimitz
Quoting unf97:


Just overcast in Jacksonville, It is too dryin the mid-upper levels for precip to reach the surface up here.

Temp 29.6 degrees at my home currently.


A steady 32 in San Marco since 0700.
Member Since: August 17, 2008 Posts: 0 Comments: 99
Was just about to say nothing but rain in Hudson FL (just north of tampa) but walked out side and you can hear it more than see it. Not sure whether to call it sleet or ice pellets. Very fine but definately FROZEN stuff.
Member Since: September 7, 2006 Posts: 5 Comments: 912
2002. unf97
Quoting IKE:
Melbourne and JAX weather offices....any updates? Wake up...hello.


Just overcast in Jacksonville, It is too dry in the mid-upper levels for precip to reach the surface up here.

Temp 29.6 degrees at my home currently.
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2001. eddye
is it comingfor se fl
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2000. WxLogic
Sleet still coming... hehe at least got some on a Styrofoam cup.
Member Since: August 14, 2008 Posts: 4 Comments: 5029
1999. eddye
is it going to snow in se fl
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Now that Florida got snow.. I will get KOG to turn off the fans... our work is done :)
Need it to warm up now.... want it really hot for next week :)
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1997. IKE
I guess that Florida sun warmed the atmosphere just enough.
Member Since: June 9, 2005 Posts: 23 Comments: 37860
1996. IKE
Quoting Orcasystems:


Did you get snow... it looked like BF did and maybe Shep also


If I did I slept through it...I don't think I did.

Found this from the Orlando News-Sentinel.....

Member Since: June 9, 2005 Posts: 23 Comments: 37860
Quoting IKE:


I'm waiting on a picture.


Did you get snow... it looked like BF did and maybe Shep also
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snowline ready to close in on my house any minute now!!!
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1993. IKE
Quoting Orcasystems:


Its definitely cooler... all I wanted was a bit of snow for Florida... it appears wishes do come true :)



I'm waiting on a picture.
Member Since: June 9, 2005 Posts: 23 Comments: 37860
A very cold rain all the way down here in South Florida in Boynton Beach. Currently 42 degrees and still dropping with a wind chill of 35.
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Quoting zoomiami:
Hi Orca:

Ha ha -- not much rain - the cold air has been very dry - its drizzling now - but they say it should rain more.

Actually - what I wanted was for it to cool off - proves the old expression "watch what you wish for" lol


Its definitely cooler... all I wanted was a bit of snow in Florida... it appears wishes do come true :)

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1990. IKE
Melbourne and JAX weather offices....any updates? Wake up...hello.
Member Since: June 9, 2005 Posts: 23 Comments: 37860
Ok I just went outside. In Oakland Park. Its pouring rain. 41 degrees.. And guess what.. a few lines sleet pellets are mixing with the rain. Its raining quite hard and the windchill is freezing !
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1988. IKE
Just reached a new morning low in Defuniak Springs,FL...24.1. Sunshine will be here shortly.
Member Since: June 9, 2005 Posts: 23 Comments: 37860
1987. chawk
We just had a pretty good sleet shower here just south of Tarpon Springs Forida. I'm 2 blocks from the Gulf and the Temp is 36F. Some of the sleet pellets are large, close to 1/8th inch. Wife tells me she heard it start about 4am. I'll get some pictures if I can figure out how to attach to this site.
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Hi Orca:

Ha ha -- not much rain - the cold air has been very dry - its drizzling now - but they say it should rain more.

Actually - what I wanted was for it to cool off - proves the old expression "watch what you wish for" lol
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Quoting zoomiami:
Local weather here in Miami says wind chill of 39 - that is very cold for us.

Have a daughter in Orlando suppose to play in soccer tournament - sure hope they cancel.


You said you were looking for rain.. did you get it :)
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Link

Wait a minute.. Look at the Orlando radar now. Its showing mixed precip all the way down to ft myer... maybe with cooling when flakes fall it will drop another 5 or 6 degrees to get snow in SFL after all
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Local weather here in Miami says wind chill of 39 - that is very cold for us.

Have a daughter in Orlando suppose to play in soccer tournament - sure hope they cancel.
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1982. IKE
Orlando 35 F Light Rain 7:53 AM EST
Orlando International 35 F Light Rain 8:53 AM EST
Kissimmee - Light Rain 8:50 AM EST
Sanford 33 F Light Rain 8:53 AM EST

Tampa Executive 32 F Overcast 8:40 AM EST
Tampa Knight Airport 34 F Overcast 8:45 AM EST
Plant City 34 F Overcast 8:45 AM EST
Tampa 35 F Overcast 8:53 AM EST
Member Since: June 9, 2005 Posts: 23 Comments: 37860
Quoting mara0921:
Link


See this regional radar. I guess alot of this isnt hitting the ground?
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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.