Where's spring? 2nd most extreme March jet stream pattern on record extends winter

By: Dr. Jeff Masters , 3:15 PM GMT on March 20, 2013

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Punxatawney Phil got it way wrong. Pennsylvania's famous prognosticating rodent predicted just three more weeks of winter back on February 2. It's the first day of spring, but winter remains firmly entrenched over the eastern half of the U.S., where temperatures of 5 - 25°F below average have been the rule all week. The culprit is the jet stream, which has taken on an unusually contorted shape that is allowing cold air to spill down over the Eastern U.S. and Western Europe, but bringing near-record warmth to portions of Greenland. One measure of how contorted the jet stream has become is by measuring the difference in pressure between the Icelandic Low and the Azores High. There are two indices used to do this--one called the Arctic Oscillation (AO), which treats the flow over the entire Northern Hemisphere, and another called the North Atlantic Oscillation (NAO), which is more focused on the North Atlantic. The two are closely related about 90% of the time. When these indices are strongly negative, the pressure difference between the Icelandic Low and the Azores High is low. This results in a weaker jet stream, allowing it to take large, meandering loops, letting cold air to spill far to the south from the Arctic into the mid-latitudes. The AO index hit -5.2 today (March 20). This is the second most extreme March value of the index since record keeping began in 1948; only an AO value of -6.3 in March 1970 was more extreme. We've had some wildly variable jet stream patterns in recent years in the Northern Hemisphere. Just last year, we had the opposite extreme in March, when our ridiculous "Summer in March" heat wave brought a week of temperatures in the 80s to the Midwest U.S. The first day of spring today in Chicago, IL is expected to have a high temperature of just 25°F--a 60 degree difference from last year's high of 85°F on March 20!


Figure 1. The jet stream is taking a large dip to the south over the Eastern U.S., allowing cold air to spill southwards and bring winter-like conditions.

Unusual winter jet stream patterns tied to Arctic sea ice loss
Unusual jet stream contortions in winter have become increasingly common in recent years, according to a March 2013 paper by Tang et al., "Cold winter extremes in northern continents linked to Arctic sea ice loss". They found a mathematical relationship between wintertime Arctic sea ice loss and the increase in unusual jet stream patterns capable of bringing cold, snowy weather to the Eastern U.S., Western Europe, and East Asia, typical of what one sees during a strongly negative Arctic Oscillation. They theorized that sea ice loss in the Arctic promotes more evaporation, resulting in earlier snowfall in Siberia and other Arctic lands. The earlier snow insulates the soil, allowing the land to cool more rapidly. This results in a southwards shift of the jet stream and builds higher atmospheric pressures farther to the south, which increases the odds of cold spells and blocking high pressure systems that can cause extended periods of unusually cold and snowy weather in the mid-latitudes.

Related posts
From Heat Wave to Snowstorms, March Goes to Extremes by Andrew Freedman of Climate Central
Extreme jet stream causing record warmth in the east, record cold in the west (January 2013)
Arctic sea ice loss tied to unusual jet stream patterns (April 2012)
Our extreme weather: Arctic changes to blame? (December 2011)
Florida shivers; Hot Arctic-Cold Continents pattern is back (December 2010)
Jet stream moved northwards 270 miles in 22 years; climate change to blame? (June 2008)

I'll have a new post on Thursday.

Jeff Masters

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Gusty Winds (novembergale)
High winds create huge waves behind ice dunes on Lake Erie this last day of winter.
Gusty Winds
After the blizzard (springsun)
Extreme severe winterconditions in the northeast of Germany, Kap Arkona. Source: wetterzentrale
After the blizzard

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Quoting AussieStorm:

Well it is 09:45 here. That's morning for me.


I was up today at 6:30 AM... as part of my extreme work schedule...
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Quoting PalmBeachWeather:
Morning??? Oh hell no... Time to get up already? Geez

Well it is 09:45 here. That's morning for me.
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Times They are a-Changin
Member Since: February 29, 2012 Posts: 0 Comments: 6258
Quoting AussieStorm:

They are beginning to turn into a regular news organisation that does weather on the side


even information about the Pope they have in there...what the heck?
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Quoting AussieStorm:
Morning all....

been not to well the last few days with back pain and migraines. Lets hope that's all over with now.

How is everyone weather. I read that the Lovett Elementary School in Mississippi will be closed for the rest of the year due to severe roof damage from the hail storm. Link That must of been some hail storm.
Morning??? Oh hell no... Time to get up already? Geez
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Quoting trHUrrIXC5MMX:
umm question???

what does "finding snakes in people's belongings at the airport" has to do with weather...

check weather.com main headlines...

They are beginning to turn into a regular news organisation that does weather on the side
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Quoting trHUrrIXC5MMX:
umm question???

what does "finding snakes in people's belongings at the airport" has to do with weather...

check weather.com main headlines...

Exactly. And what does "Reef Wranglers", "Iron Men", etc. Have to do with weather? I can barely get a weather forecast from them on TV any more!
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Quoting RTSplayer:


Really? I never dreamed I was Batman.
Think thoughts of Adam West
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Morning all....

been not to well the last few days with back pain and migraines. Lets hope that's all over with now.

How is everyone weather. I read that the Lovett Elementary School in Mississippi will be closed for the rest of the year due to severe roof damage from the hail storm. Link That must of been some hail storm.
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Quoting Grothar:


I think it was raining at the time.


well wether it was or not... I think this is more of a CNN/Fox news kinda think to take care of but what do you know? even weather takes over
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Quoting PalmBeachWeather:
Gro... I had one of those severe senior moments last night while I was cruisin' Palm Beach... Now there is 2 Jaguars,1 Lamorghini, and a Ferrari in my driveway... Oh yeah.. This 25 year old guy in cutoff bluejeans is dancing in my front yard... My neighbor said I came home last night in a pink Limo and I got out smiling... Sure sucks to have that "senior moment" thingy...


Really? I never dreamed I was Batman.
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Quoting trHUrrIXC5MMX:
umm question???

what does "finding snakes in people's belongings at the airport" has to do with weather...

check weather.com main headlines...


I think it was raining at the time.
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Member Since: Posts: Comments:
umm question???

what does "finding snakes in people's belongings at the airport" has to do with weather...

check weather.com main headlines...
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Quoting Grothar:


Ah, the good old days. I haven't seen that since last year. Maybe I might take out my globe.


LOL...Please don't do this to me. You want to get me banned again, don't you?
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Quoting GeoffreyWPB:
Have to make sure IntelliGeoff is still working...



Ah, the good old days. I haven't seen that since last year. Maybe I might take out my globe.
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Quoting Grothar:


I thought I was having a severe "senior" moment.
Gro... I had one of those severe senior moments last night while I was cruisin' Palm Beach... Now there is 2 Jaguars,1 Lamorghini, and a Ferrari in my driveway... Oh yeah.. This 25 year old guy in cutoff bluejeans is dancing in my front yard... My neighbor said I came home last night in a pink Limo and I got out smiling... Sure sucks to have that "senior moment" thingy...
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Quoting TropicalAnalystwx13:

Here's the right link. Sorry.

Link


Basin area is defined differently between the two:








Edit: Added correct second gif
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Have to make sure IntelliGeoff is still working...

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Quoting trHUrrIXC5MMX:


I want to hear your words and his words again after NHC comes up with their numbers later in May


how can someone with a screen name of yonzabam not want to have fun?
Member Since: August 19, 2006 Posts: 13 Comments: 16225
Quoting TropicalAnalystwx13:
Conflicting graphics...both official. Both updated today. Both for the tropical Atlantic.




^ Cropped.

The bottom one is correct.
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Quoting Grothar:


You never listen to me. :)


I always listen to you Gro. You have the best "connections" of all the bloggers. :)
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Quoting MAweatherboy1:
There's supposed to be a Norlun trough setting up somewhere over SE MA/Cape Cod tomorrow night. These things are so fickle and almost impossible to predict, but they can produce high snow amounts if you get stuck under one. My local NWS's forecast is probably a little conservative, I'm thinking at least some areas of 2-4" with isolated 5-6" amounts over SE Mass where the heavy band sets up, models seem to be trending higher with the precip amounts, except the 12z Euro, which may explain the caution of the NWS.



I'll do a map for this...seems somewhat interesting, could the snow shift (maybe a little? either direction at this point...?
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Quoting GeoffreyWPB:


Yes, it is my guess.


You never listen to me. :)
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Quoting TropicalAnalystwx13:

Scroll down.

Link
Who would haver thought that 20 years ago 100% of the people would have understood what the term "Scroll Down" means... The times they are A CHANGIN'
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Quoting TropicalAnalystwx13:

Scroll down.

Link
Quoting TropicalAnalystwx13:

EDIT: Hold on, wrong one.

Here's the right link. Sorry.

Link
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Quoting bappit:

Last time I saw green clouds was when Allison dumped up to three feet of rain over night. The clouds held so much liquid water the reds were being filtered out. No hail. No lightning to speak of.


The green color generally is due to hail, it probably was hail elevated well into the thunderstorm top producing the green color. The greenish color in tropical convection normally just indicates extremely heavy rain as its likely no ice will make it near the ground. However, the cell producing the greenish color you saw is probably due to strong updrafts and very tall thunderstorm tops allowing for some sort of hail formation way up in the cloud.
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There's supposed to be a Norlun trough setting up somewhere over SE MA/Cape Cod tomorrow night. These things are so fickle and almost impossible to predict, but they can produce high snow amounts if you get stuck under one. My local NWS's forecast is probably a little conservative, I'm thinking at least some areas of 2-4" with isolated 5-6" amounts over SE Mass where the heavy band sets up, models seem to be trending higher with the precip amounts, except the 12z Euro, which may explain the caution of the NWS.

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EDIT: Hold on, wrong one.
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Quoting trHUrrIXC5MMX:


no, you weren't because I'll have been in your camp otherwise, saw that too
One time in Band Camp
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Quoting yonzabam:


Nah. It's the lightning shining through the hail. See a green storm, get the car in the garage and board up the windows. It might be golfball sized hail.

Last time I saw green clouds was when Allison dumped up to three feet of rain over night. The clouds held so much liquid water the reds were being filtered out. No hail. No lightning to speak of.
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Quoting TropicalAnalystwx13:

Both of those graphs I used in my first post were calculating vertical instability by your first definition and still disagree.


You have the source for the second graphic? Not the imgur source.
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Quoting Grothar:


I thought I was having a severe "senior" moment.


no, you weren't because I'll have been in your camp otherwise, saw that too
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Quoting trHUrrIXC5MMX:


Grothar is with Pedley for 18-6-3...

So 16-9-3 is your bet?


Yes, it is my guess.
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Quoting VR46L:


Glad I was not the only one who saw it !

I would have said paranoid hallucinations were taking a grip otherwise.


I thought I was having a severe "senior" moment.
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Heavy thunderstorm just crossed central M-D County. Barely any wind associated with it though.
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Quoting trHUrrIXC5MMX:


you made me laugh so loud... gotta be Palm Beach
My Max
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Quoting nrtiwlnvragn:


Not calculated the same.

Experimental

THDV: The average vertical instability parameter, defined as the vertical average temperature difference between the equivalent potential temperature of a parcel lifted from the surface to 200 hPa, and the saturation equivalent potential temperature of the environment.

**Note: all parameters except DNST computed over a 500km radius area centered on each grid point


Official

VERTICAL INSTABILITY: The vertical average temperature difference between the equivalent potential temperature of a parcel lifted from the surface to 200 hPa, and the saturation equivalent potential temperature of the environment, for each 5 by 5 degree area.

Both of those graphs I used in my first post were calculating vertical instability by your second definition and still disagree.
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Quoting PalmBeachWeather:
Not sure what you are betting on, but I go with Ohio State Buckeyes in the finals


you made me laugh so loud... gotta be Palm Beach
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Quoting TropicalAnalystwx13:
Conflicting graphics...both official. Both updated today. Both for the tropical Atlantic.




^ Cropped.


Not calculated the same.

Experimental

THDV: The average vertical instability parameter, defined as the vertical average temperature difference between the equivalent potential temperature of a parcel lifted from the surface to 200 hPa, and the saturation equivalent potential temperature of the environment.

**Note: all parameters except DNST computed over a 500km radius area centered on each grid point


Official

VERTICAL INSTABILITY: The vertical average temperature difference between the equivalent potential temperature of a parcel lifted from the surface to 200 hPa, and the saturation equivalent potential temperature of the environment, for each 5 by 5 degree area.
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Quoting trHUrrIXC5MMX:


Grothar is with Pedley for 18-6-3...

So 16-9-3 is your bet?
Not sure what you are betting on, but I go with Ohio State Buckeyes in the finals
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Quoting jonger1150:


This website is generally constant tropical updates and the layout stinks... Why would I comment much on tropical systems living in Michigan?


Dr. Masters seems to be interested in tropical weather and he is from Michigan. He still lives there yet somehow maintains his interest.
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.
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Quoting intampa:
hey largo im confused... i keep seeing the radar maps people post here and it looks like rain headed to tampa. then i look at baynews9 radar and looks like not much coming here, its all going south... i will admit i dont know much about these loops etc but do you think there maybe rain for tampa after all. we need it as im sure you know.



Bay news 9 radar shows the same thing, if anything, it has a bit higher definition at long range than competing radar imagery. However, all radars use the same Doppler technique, there isn't any difference. Plenty of rain is on the way for the Tampa Bay area, but cooler shelf waters will likely weaken the activity some, limiting lightning and stronger cells. It will mostly be steady rain with embedded heavier showers. The lack of deep tropical moisture will prevent torrential down pours.
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Quoting yonzabam:


Nah. It's the lightning shining through the hail. See a green storm, get the car in the garage and board up the windows. It might be golfball sized hail.



It depends on where you live, growing up in Central FLorida, I've seen that dark green color every summer in some of the stronger thunderstorms we experience, but rarely do we actually experience hail. That is because it is hail at cloud level but melts into rain near the ground. I've seen where the radar showed a large hail core of 2.25 in. move right over me in August last year with a large VIL and 67 DBZ, had the dark green color, but no hail. Just extremely heavy rain with huge rain drops, some of which seemed strangely huge. I've seen the unusually large rain drops before with severe thunderstorms and following the green sky.

I have seen large hail a few times in the Tampa Bay area but it was always in the winter and early spring and only to about quarter size in the largest stones.

Not to say we can't get large hail in the summer, it does happen sometimes and days with unusually cold air aloft or some dry air aloft but typically the atmosphere is too warm through the column and more importantly, too much saturation.

Large hail is most favorable in severe thunderstorms with very steep lapse rates beginning even at 850 mb along with a presence of at least substantial dry air at some given layer of the atmosphere.

In other words, the more tropical the air mass, the less likely for hail.
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Quoting TropicalAnalystwx13:

Let's add another one.



The vertical instabilty graph is so strongly correlated with the peak of the hurricane season, that it's surprising it's not more recognized as the important factor it obviously is.
Member Since: July 20, 2008 Posts: 0 Comments: 3013
Quoting VR46L:


I could have swore I saw a different Graphic before I refreshed the page ....
sometimes things change in but a blink of an eye

)
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Quoting TropicalAnalystwx13:
Conflicting graphics...both official. Both updated today. Both for the tropical Atlantic.




^ Cropped.

Let's add another one.

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I just finished up my preseason forecast for the 2013 East Pac season. I'm expecting near to below average activity out there this year.

Link
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Quoting RTSplayer:


Being entertained by calamities actually is a problem.


Depends on how you look upon the storms.

I see them as a refreshing opportunity to roll the dice and just have fun predicting mother nature.

Calamity? Hardly. For those who are in mother nature's path may refer to them as calamities, but I see them in a different light. I see them as a necessity to keep Earth's climatic cycles in check, they distribute excess energy across the face of this planet.

It helps to not call them calamities when one lives far enough away from the shore.

Not sure how predicting numbers for a season of storms is paramount to a "problem". Most of those who do so know full well the dangers associated with these beasts of nature.
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Quoting VR46L:


I could have swore I saw a different Graphic before I refreshed the page ....



I saw this chomp dog...lol
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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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