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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2379. IKE
35.1....here. If it gets under 20.0 here I'll be surprised. Too many lakes around.
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Under freezing in Tallahassee now 31.8 degrees.
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2376. KEEPEROFTHEGATE (Mod)
Member Since: July 15, 2006 Posts: 169 Comments: 53296
2375. KEEPEROFTHEGATE (Mod)
i could use a nice 50 degree day still got 71 or so days till the first of spring
Member Since: July 15, 2006 Posts: 169 Comments: 53296
2374. KEEPEROFTHEGATE (Mod)
ya i know too bad it isn't hot air
Member Since: July 15, 2006 Posts: 169 Comments: 53296
2373. IKE
KOTG...that's a lot of wind....
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2372. KEEPEROFTHEGATE (Mod)






Member Since: July 15, 2006 Posts: 169 Comments: 53296
2371. Patrap
The GOM Storm will form,..too many guidance parameters and history on that kinda scenario.

The Long Bumpy winter continues for weather weenies Worldwide.,in the N Hemisphere.



And for the Climate Change topic crowds,there is Australia and heat and Indian Typhoons too.

Lots to watch Globally...for us weather weenies.
Member Since: July 3, 2005 Posts: 421 Comments: 127592
2370. IKE
Quoting Floridano:


OMG, I'm terribly sorry to hear about that, :(. Heart-breaking.


If you want some firewood, you're welcome to bring a hammer and disassemble that dock.


Quoting BahaHurican:
Wow, Ike. I didn't realize your dog had died so recently! My condolences go out to you.... Now I understand the reason for the icon switch.


It's alright. I got a black poodle staring at me making faces....crackin me up...

35.8 outside.
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32.5 now almost a freezing.
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Quoting BahaHurican:
Wow, Ike. I didn't realize your dog had died so recently! My condolences go out to you.... Now I understand the reason for the icon switch.


same here.
Member Since: Posts: Comments:
Wow, Ike. I didn't realize your dog had died so recently! My condolences go out to you.... Now I understand the reason for the icon switch.
Member Since: Posts: Comments:
Quoting Patrap:
Latest Guidance in the NWS Discussion here,..a lil faster and closer in time now,Thurs -Fri event.

818
fxus64 klix 092154
afdlix


Area forecast discussion
National Weather Service New Orleans la
354 PM CST Sat Jan 9 2010


Short term...
water vapor imagery shows deep shortwave trough associated with
core of Arctic air moving into the lower Mississippi Valley and
southeast states...accompanied by reinforcement of strong surface
high pressure. Cold air advection will continue through Sunday
morning...then the Arctic surface high will becoming centered over
the central Gulf Coast Sunday night. Very cold...but not
record...low temperatures will continue the next couple nights.
A hard freeze warning is in effect tonight and a hard freeze watch
will be issued for Sunday night. Minimum wind chill values will be
10 to 15 degrees late tonight and early Sunday
morning...especially south and near the coast where winds will
remain up near 10 or 10 to 15 miles per hour. Will issue a Wind Chill
Advisory for the entire forecast area that will be from midnight
to 9 am Sunday.


Highs on Sunday will probably be below the mav guidance once again
given the high bias that MOS has had the last few days. Still...we
should see most locations get above 40 degrees for highs. Lows
Sunday night should be the coldest of this cold outbreak...with
values ranging from 16 to 20 north to the lower to middle 20s south
of Lake Pontchartrain. Highs on Monday will warm to around 50
degrees which will feel rather mild even though it is still 10
degrees below normal.


Long term...
another shortwave trough will bring a reinforcement of high
pressure Monday night...however...the airmass will be modifying
due to rising heights aloft. The next surface high will move down
on the Gulf south late Tuesday and Tuesday night...however...an
upper ridge will also build over our area. This will produce some
large diurnal temperature ranges. Monday night lows will be very
cold once again over the north and east with yet another hard
freeze...then only a light freeze is expected Tuesday night. Highs
will be warming through the 50s.


The next large low pressure system moving near the western and
central Gulf Coast will bring the next chance of rain and showers
Thursday into Friday with the best chance of showers and isolated
thunderstorms...with heavy rainfall potential...Friday night and
Saturday. There is a little better model consistency between the
GFS and European model (ecmwf) today
.


22/dew point
&&


That is not good. Makes it a lot more likely to happen.
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2365. Patrap
Brrrrrrrrr....


Member Since: July 3, 2005 Posts: 421 Comments: 127592
Quoting IKE:


I do too. Unfortunately he's dead. He drowned in this darn lake(my lake front house), New Years evening about 6 pm. I let him out to use the can...he took a 300 foot walk to my dock...up the ramp.....fell off of the dock and drowned. A 13 year, 11 month...7 pound...near blind poodle.....



I've google searched prior events like this and found zilch.

Find more here if interested....Link


OMG, I'm terribly sorry to hear about that, :(. Heart-breaking.
Member Since: Posts: Comments:
2363. Patrap
Latest Guidance in the NWS Discussion here,..a lil faster and closer in time now,Thurs -Fri event.

818
fxus64 klix 092154
afdlix


Area forecast discussion
National Weather Service New Orleans la
354 PM CST Sat Jan 9 2010


Short term...
water vapor imagery shows deep shortwave trough associated with
core of Arctic air moving into the lower Mississippi Valley and
southeast states...accompanied by reinforcement of strong surface
high pressure. Cold air advection will continue through Sunday
morning...then the Arctic surface high will becoming centered over
the central Gulf Coast Sunday night. Very cold...but not
record...low temperatures will continue the next couple nights.
A hard freeze warning is in effect tonight and a hard freeze watch
will be issued for Sunday night. Minimum wind chill values will be
10 to 15 degrees late tonight and early Sunday
morning...especially south and near the coast where winds will
remain up near 10 or 10 to 15 miles per hour. Will issue a Wind Chill
Advisory for the entire forecast area that will be from midnight
to 9 am Sunday.


Highs on Sunday will probably be below the mav guidance once again
given the high bias that MOS has had the last few days. Still...we
should see most locations get above 40 degrees for highs. Lows
Sunday night should be the coldest of this cold outbreak...with
values ranging from 16 to 20 north to the lower to middle 20s south
of Lake Pontchartrain. Highs on Monday will warm to around 50
degrees which will feel rather mild even though it is still 10
degrees below normal.


Long term...
another shortwave trough will bring a reinforcement of high
pressure Monday night...however...the airmass will be modifying
due to rising heights aloft. The next surface high will move down
on the Gulf south late Tuesday and Tuesday night...however...an
upper ridge will also build over our area. This will produce some
large diurnal temperature ranges. Monday night lows will be very
cold once again over the north and east with yet another hard
freeze...then only a light freeze is expected Tuesday night. Highs
will be warming through the 50s.


The next large low pressure system moving near the western and
central Gulf Coast will bring the next chance of rain and showers
Thursday into Friday with the best chance of showers and isolated
thunderstorms...with heavy rainfall potential...Friday night and
Saturday. There is a little better model consistency between the
GFS and European model (ecmwf) today
.


22/dew point
&&
Member Since: July 3, 2005 Posts: 421 Comments: 127592
Quoting P451:


Depending on the region they will issue advisories. They'd never issue a wind chill advisory up in the northern states unless you're talking below zero wind chills.

It's the same with winter storm warnings. You need 6"+ forecast for a winter storm warning for where I live in NJ, but, in say SE Virginia they will issue a winter storm warning for less than 4 inches - just because they aren't used to such weather.

Same with the wind chill advisories. There is no static criteria in regards to issuing them.

They tailor them to geographic regions.

It makes sense to some degree.



Yep hard freeze, or freeze warnings prob don't exist in the NE as an example. Or are they used only once?
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2361. IKE
Quoting Floridano:
I love your doggie, Ike! He's adorable.


I do too. Unfortunately he's dead. He drowned in this darn lake(my lake front house), New Years evening about 6 pm. I let him out to use the can...he took a 300 foot walk to my dock...up the ramp.....fell off of the dock and drowned. A 13 year, 11 month...7 pound...near blind poodle.....



I've google searched prior events like this and found zilch.

Find more here if interested....Link
Member Since: Posts: Comments:
2359. Patrap
Quoting plywoodstatenative:
Pat, whats the deal with this forecast. are we looking at either a late or early season non tropical type low developing?


It wont be Tropical,its January and one needs a warm core,more Likely a Strong STS.
No matter the name,lack thereof,or class,..itsa progged to be a Real Big one,and one should pay attention along the N Gulf Coast as for Impact and effects.

The System looks to make Landfall between 6pm Friday and Noon Saturday.

Stay tuned..things will become clearer come Tues-Weds.
Member Since: July 3, 2005 Posts: 421 Comments: 127592
Pat, whats the deal with this forecast. are we looking at either a late or early season non tropical type low developing?
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2355. jipmg
low-mid 30s is the forecast for metro DADE which includes coral springs.

Anyhow, 39 is being reported on weather bug just south of the air port
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I love your doggie, Ike! He's adorable.
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Quoting Jeff9641:


I've been saying this would happen since last weekend. A very dangerous storm is on the horizon late next week. This storm could have hurricane force winds with it. NOLA to Florida really need to watch this one.


All of Florida; including the southern peninsula? :)
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2350. IKE
36.9 at my house.
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Wind pretty calm despite the wind chill advisories.
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2347. Patrap
just type Coral Springs in the search box at the top of the page,or a Zip Code.

Answers Beaucoup,will appear cher
Member Since: July 3, 2005 Posts: 421 Comments: 127592
2346. jipmg
Humidity still crazy high, 90-95% in SFL temps around 40 all around dade
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Temperature down to 40 degrees while South Florida is still covered by a shield of rain. The race is on to whether the rain ends before the sleet/snow can begin.
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2343. flsky
Beautiful sunset in Daytona Beach Shores at the moment. Nice to see the sun again! Still a windchill temp of 30 tho.
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What are we looking at in South Florida for temps tomorrow night, along with wind chills? Need to know for the area of Coral Springs, as I have soccer, (gulp) for tomorrow night.
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Starting to drop 33 degrees now.
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Quoting IKE:


stormtop may show back up.

Cat 3 in the GOM.


Good one, Ike! ROFL!!!
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Quoting IKE:


stormtop may show back up.

Cat 3 in the GOM.


unless stormtops mom stops him from entering his basement weather office.
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2336. Patrap
I may have a Gale warning for my B-day Party Ike..woo,hoo
Member Since: July 3, 2005 Posts: 421 Comments: 127592
2335. IKE
Quoting Floridano:


Good heavens, imagine seeing something like that, during cane season, LOL.


stormtop may show back up.

Cat 3 in the GOM.
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Quoting IKE:
168 hour 18Z GFS....wow!!!



It shows a derecho stretching to Cuba too. Thank goodness this is 168hrs away.
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2333. Patrap
Quoting Floridano:


Good heavens, imagine seeing something like that, during cane season, LOL.


We have,..minus the LOL
Member Since: July 3, 2005 Posts: 421 Comments: 127592
2332. KEEPEROFTHEGATE (Mod)


here is the system at the 168 hr mark
Member Since: July 15, 2006 Posts: 169 Comments: 53296
2331. Patrap
Member Since: July 3, 2005 Posts: 421 Comments: 127592
Quoting IKE:
156 hour 18Z GFS....



Good heavens, imagine seeing something like that, during cane season, LOL.
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Even if they use Tally's airport as the high it will be around 26 deg below the average high.
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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.

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