The climate is changing: the Arctic Dipole emerges
The dramatic loss of Arctic sea ice in recent years has created a fundamental new change in the atmospheric circulation in the Northern Hemisphere that has sped up sea ice loss and is affecting fall and winter weather across most of the Northern Hemisphere, according to several recent studies. Arctic sea ice loss peaks in September and October, exposing a large area of open water that heats the air above it. This extra heat has helped drive September - November air temperatures in the Arctic to 1°C (1.8°F) or more above average over about half of the depth of the lower atmosphere (Figure 1). This deep layer of warm air has grown less dense and expanded, pushing the top of the troposphere (the lower atmosphere) higher. The result has been a decrease in the pressure gradient (the difference in pressure) between the North Pole and mid-latitudes. With not as much difference in pressure to try and equalize, the jet stream has slowed down in the Arctic, creating a major change in the atmospheric circulation for the Northern Hemisphere.
Figure 1. Cross section of Arctic temperature anomaly from 1000 mb (the surface) to 300 mb (roughly, the height of the top of the lower atmosphere or troposphere). Cross section is taken along the Date Line (180°W), from 60°N latitude (left side) to the North Pole (right side), for September - November for the 12-year period 1998 - 2009. Three year averages were done to reduce the amount of year-to-year noise associated with natural variation. Other cross sections along different lines of longitude show similar results, though typically with more warming aloft and less warming at the surface. Image credit: NOAA/ESRL.
A new atmospheric pattern emerges: the Arctic Dipole
In a 2008 article titled, Recent radical shifts of atmospheric circulations and rapid changes in Arctic climate system Zhang et al. show that the extreme loss of Arctic sea ice since 2001 has been accompanied by a radical shift of the Arctic atmospheric circulation patterns, into a new mode they call the Arctic Rapid change Pattern. The new atmospheric circulation pattern has also been recognized by other researchers, who refer to it as the Arctic Dipole (Richter-Menge et al., 2009). The old atmospheric patterns that controlled Arctic weather--the North Atlantic Oscillation (NAO) and Arctic Oscillation (AO), which featured air flow that tended to circle the pole, now alternate with the new Arctic Dipole pattern. The Arctic Dipole pattern features anomalous high pressure on the North American side of the Arctic, and low pressure on the Eurasian side. This results in winds blowing more from south to north, increasing transport of heat into the central Arctic Ocean. The Arctic Dipole pattern occurred in all summer months of 2007 and helped support the record 2007 summer reduction in sea ice extent (Overland et al., 2008). Overland et al., 2010 also found that the Arctic Dipole pattern tended to create an increase in easterly winds in the lower half of the atmosphere of 40% in fall, between 2002 - 2008. Fall 2008 through spring 2009 featured the old AO pattern. The new Arctic Dipole pattern re-appeared in June - July 2009, but the old AO pattern dominated in August - September, resulting in greater sea ice extent than in 2007 and 2008. The Arctic Dipole pattern was active again in October, inactive in November, and reasserted itself this December. As a result, Arctic sea ice reached a new record minimum for a 10-day period in early November, increased above record lows during late November and early December, and appears poised again to reach a new record minimum later this December (Figure 2).
Figure 2. Sea ice extent in the Arctic for this year (blue line) compared to the record low year of 2007 (green line) and 1979 - 2000 average (gray line). One could make the ice loss looks less significant by using the full satellite data record from 1979 - 2008 for the average. Image credit: National Snow and Ice Data Center.
Arctic Dipole blamed for colder winters in East Asia
It turns out that the new Arctic circulation patterns help to intensify the Siberian High, a large semi-permanent region of surface high pressure prevalent in winter over Siberia. According to Honda et al. (2009), this results in increased flow of cold air out of the Arctic in early winter over eastern Russia, Japan, Korea, and eastern China, causing colder temperatures. By late winter, the pattern shifts, resulting in colder than average temperatures from East Asia to Europe.
Arctic Dipole blamed for drier winters in Northern Europe
Francis et al. (2009) found that during 1979 - 2006, years that had unusually low summertime Arctic sea 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--a pattern that usually brings reduced winter precipitation over Alaska and Northern Europe and increased precipitation over Southern Europe. A more negative NAO also tends to bring cold winters to eastern North America and Europe. Though it was not mentioned in the article, reduced Arctic sea ice may also cause dry early winter conditions in the U.S. and the Caribbean (Figure 3). The authors noted that strong La Niña or El Niño events can have a much larger influence on the wintertime atmospheric circulation, which will overshadow the changes due to Arctic sea ice loss.
Figure 3. Difference in early winter precipitation (November - January) between five years that had low Arctic sea ice (2005, 2006, 2007, 2008, and 2009), and five years that had unusually high Arctic sea ice extent (1981, 1984, 1986, 1989, 1993). Note that low sea ice may be responsible for dry conditions in early winter for the Caribbean and most of the U.S.
Commentary
Arctic sea ice loss appears to have created a new atmospheric circulation pattern that brings more warm air in the Arctic, creating a positive feedback loop that causes even more sea ice loss. This feedback loop increases the likelihood that an ice-free Arctic in the summer will indeed come by 2030, as many Arctic experts are predicting. It's worth noting that such an atmospheric circulation shift was not predicted by the climate models. Indeed, the loss of Arctic sea ice over the past three years exceeds what any of our models were predicting (Figure 4). While we can rightly criticize these models for their inaccuracy, we should realize that they are just as capable of making errors not in our favor as they are of making errors in our favor.
Figure 4. Arctic sea ice extent from observations (thick orange line) and 13 model forecasts used to formulate the 2007 IPCC report (light lines). The thick black line is the multi-model ensemble mean, with the standard deviation plotted as a dashed black line. Image has been updated to include the observed 2008 and 2009 measurements. None of the models predicted the record 2007 sea ice loss. Image credit: Arctic sea ice decline: Faster than forecast by Stroeve et al., 2007.
References
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", Geophysical Research Letters, 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., M. Wang, and S. Salo, 2008: The recent Arctic warm period, Tellus, 60A, 589.597.
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.
Richter-Menge, J., and J.E. Overland, Eds., 2009: Arctic Report Card 2009, http://www.arctic.noaa.gov/reportcard.
Simmonds, I., and K. Keay (2009), Extraordinary September Arctic sea ice reductions and their relationships with storm behavior over 1979.2008, Geophys. Res. Lett., 36, L19715, doi:10.1029/2009GL039810.
Wu, B., J. Wang, and J. E. Walsh, 2006: Dipole anomaly in the winter Arctic atmosphere and its association with sea ice motion. J. Climate, 19, 210-225.
Zhang, X., A. Sorteberg, J. Zhang, R. Gerdes, and J. C. Comiso (2008), Recent radical shifts of atmospheric circulations and rapid changes in Arctic climate system, Geophys. Res. Lett., 35, L22701, doi:10.1029/2008GL035607.
Jeff Masters
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Entire story: Link
latimes.com
Rainstorm wallops Southern California
Moderate to heavy showers over wildfire-denuded hillsides send mud and rocks tumbling onto roads, trapping about 90 vehicles and forcing evacuations of more than 40 homes.
By Ruben Vives and Tony Barboza
9:39 PM PST, December 12, 2009
The strongest of three back-to-back rainstorms is expected to clear out by midday today after walloping Southern California on Saturday, sending mud and rocks tumbling onto roads, trapping about 90 vehicles on mountainous Angeles Crest Highway for hours and causing officials to issue mandatory evacuation orders for more than 40 homes.
There were no reports of major damage or injuries late Saturday night. But more rainfall was expected overnight and into the morning, further saturating wildfire-denuded hillsides.
Has list of road closures.
Entire story: Link
Flooding in three coastal counties
Posted: Dec 13, 2009 12:01 AM EST Updated: Dec 13, 2009 12:30 AM EST
By Krystal Allan – bio | email
HARRISON COUNTY, MS (WLOX) - With all of the rain, emergency officials are asking driver to avoid some areas. Emergency officials say Highway 90 has had flooding problems throughout the three coastal counties.
I might snap a photo in the morning but I doubt ill be awake and its suppose to change back to cold rain by 8am.
I've sent you a WU e-mail.
Tropical Cyclone Advice Number 17
TROPICAL CYCLONE LAURENCE (01U)
5:00 pm ACST December 13 2009
==========================================
At 3:30 pm CST [2:00 pm WST], Tropical Cyclone Laurence, Category 1 (1001 hPa) located at 12.7S 128.0E has 10 minute sustained winds of 35 knots with gusts of 50. The cyclone was estimated to be 230 kms northeast of Kalumburu and 490 kms northeast of Kuri Bay and moving west northwest at 7 knots
Dvorak Intensity: T3.0/3.0/D0.5/ 24hrs
Gale Force Winds
================
50 NM from the center
Tropical cyclone Laurence is expected to move west or west southwest parallel to the north Kimberley coast in Western Australia.
GALES with gusts to 100 kilometres per hour may develop on the north Kimberley coast during Monday if the cyclone moves closer to the coast.
HEAVY RAIN may develop in the far north Kimberley region later on Monday or Tuesday if the cyclone moves closer to the coast.
Tropical Cyclone Watches/Warnings
===================================
A Cyclone WARNING is now current for coastal areas from Kuri Bay to Wyndham.
A Cyclone WATCH is now current for coastal areas from Cape Leveque to Kuri Bay,
not including Derby.
Forecast and Intensity
=======================
12 HRS: 12.5S 126.7E - 40 knots (CAT 1)
24 HRS: 12.8S 125.5E - 50 knots (CAT 2)
48 HRS: 13.6S 123.5E - 55 knots (CAT 2)
72 HRS: 14.9S 122.4E - 55 knots (CAT 2)
Additional Information
=======================
Tropical Cyclone Laurence has relocated near 12.7S 128.0E, based on recent visible imagery showing partially exposed LLCC. The system is sheared with the LLCC being steered west by a low-level ridge to the south, while a residual mid-level circulation and deep convection is located further east. Dvorak assessment: DT=3.0 based on shear pattern with well defined LLCC; FT=MET=3.0. Short term movement of shallow LLCC expected to be west/northwest, while deep layer steering is weak due to a break in the subtropical ridge at 500hPa to the south. Most models forecast westward movement in the short term except GFS which moves a deep circulation towards the southwest. Slow development rate forecast for first 24 hours until low-level ridge influence declines, allowing redevelopment of vertical system. The cyclone is forecast to reach storm force within 24 hours.
In the longer term, development potential may be hampered by vertical wind shear. Movement in the next 24 hours is expected to be generally westward, while in the 48-72 hour period it is likely to be southwestwards towards the Kimberley coast west of 125E, as an upper trough approaches from the west and the mid-level ridge to the southeast becomes the dominant steering influence.
Tropical Disturbance Advisory Number 3
TROPICAL CYCLONE MICK (01F)
18:00 PM FST December 13 2009
========================================
TROPICAL CYCLONE WARNING.
A TROPICAL CYCLONE GALE WARNING REMAINS IN FORCE FOR VANUA LEVU, TAVEUNI, VITI LEVU, YASAWA AND MAMANUCA, LOMAIVITI GROUP AND NEARBY SMALLER ISLANDS.
A TROPICAL CYCLONE ALERT REMAINS IN FORCE FOR THE REST OF FIJI. A STRONG WIND WARNING REMAINS IN FORCE FOR ROTUMA.
At 6:00 AM UTC, Tropical Cyclone Mick (995 hPa) located at 14.8S 175.8E has 10 minute sustained winds of 35 knots and is reported as moving southeast at 10 knots. Position FAIR based on Multispectral satellite enhanced infrared imagery with animation and peripheral observations and peripheral observations.
Gale Force Winds
==================
150 NM from the center in sectors from north through east to southeast
100 NM elsewhere
Organization remains good in the last 12 hours. System lies under diffluent region. Outflow good to north and east. Dry air entrainment persisting from north. Warming central region evident. Primary band to east continually peeling off. Cyclone moving into area of decreasing shear. System steered by a northwest deep layer mean flow.
Dvorak based on 0.6 wrap on LOG10 spiral yielding DT 3.0, PT=3.0 MET=2.5
THUS T3.0/3.0/1.0/24HRS
Most global models agree on intensification in the short term and a forecast southeast track.
Forecast and Intensity
=======================
12 HRS 16.1S 176.9E - 40 knots (CAT 1)
24 HRS 17.3S 178.0E - 40 knots (CAT 1)
47 HRS 19.3S 179.2E - 40 knots (CAT 1)
Tropical Cyclone Advisory Number TWENTY-ONE
DEEP DEPRESSION, FORMER WARD (BOB05-2009)
11:30 AM IST December 13 2009
============================================
At 6:00 AM UTC, Deep Depression, Former Ward over southwest Bay of Bengal slightly moved southward and lay centered near lat. 9.0N 83.0E, about 200 km east-northeast of Trincomalee (Sri Lanka), 400 km southeast of Nagapattinam and 400 km east of Pamban.
The system is likely to move in a westerly direction and cross north Sri Lanka near Lat. 9.0N around early tomorrow morning. Subsequently, it is likely to move in a west-southwesterly direction, emerge into Gulf of Mannar and cross south Tamil Nadu coast between Kanyakumari and Pamban around early Tuesday morning
Tropical Cyclone Advisory Number ONE
PERTURBATION TROPICALE 07-20092010
10:00 AM Réunion December 13 2009
=========================================
At 6:00 AM UTC, Tropical Disturbance 07R (1002 hPa) located at 10.0S 84.1E has 10 minute sustained winds of 25 knots with gusts of 35 knots. The disturbance is reported as moving south-southwest at 7 knots.
RMSC Dvorak Intensity: T2.0
Forecast and Intensity
========================
12 HRS: 11.4S 82.5E - 30 knots (DEPRESSION Tropicale
24 HRS: 12.5S 81.1E - 40 knots (Tempête Tropicale Moderée)
48 HRS: 13.7S 77.8E - 50 knots (Forte Tempête Tropicale)
72 HRS: 14.3S 75.0E - 70 knots (CYCLONE Tropical)
Additional Information
======================
The system is expected to develop, due to a good upper level environment, and warm sea surface temperature. Tracking west southwestward on the northern edge of the subtropical high.
Tropical Cyclone Advisory Number TWENTY-EIGHT
PERTURBATION TROPICALE, FORMER CLEO (06-20092010)
10:00 AM Réunion December 13 2009
=========================================
At 6:00 AM UTC, Tropical Disturbance, Former Cleo (1000 hPa) located at 14.9S 61.9E has 10 minute sustained winds of 25 knots with gusts of 35 knots. The disturbance is reported as moving west-southwest at 8 knots.
Dvorak Intensity: T2.0
Forecast and Intensity
========================
12 HRS: 16.0S 60.9E - 30 knots (DEPRESSION Tropicale)
24 HRS: 17.6S 60.4E - 25 knots (PERTURBATION Tropicale)
48 HRS: 20.0S 60.4E - 20 knots (DEPRESSION se Comblant)
72 HRS: 21.8S 61.5E
Additional Information
======================
Convection has rebuilt over the center last night. Mainly due to the weakening of vertical wind shear, so the system can re-intensify temporarily bursted by the poleward outflow. The system is coming over less energetic water, and the approaching trough is expected to be unfavorable up to 24 hours, and cause the recurve of the track southeastward.
At this stage of intensity regular 6 hours advisories are not needed..
----
ghost of Cleo
I totally agree with you, deforestation, desertfication, population, Extermination of ground water via wells and Over fishing are more important that CO2 levels, If there is not enough suitable to grow crops on, fish in the ocean to eat, more will die from starvation than a rise in sea levels and changes in weather condition.
Easy answer to paragraph one.
How hard do they have to work for their fees when its a 'carbon credit' versus helping replace trees or some such?
Deforestation, desertification, over population, over fishing or dry water wells all mean getting ones hands dirty and that is simply not what AGW is all about.
For them its...Dirty hands??...OMG!!!...this is about carbon credits...why should we get our hands dirty? Yech!!
Thanks for reminding us about those other issues facing our planet.
Australian Government Bureau of Meteorology
Northern Territory
Darwin Regional Forecasting Centre
TOP PRIORITY FOR IMMEDIATE BROADCAST
Media: The Standard Emergency Warning Signal should NOT be used with this
warning.
TROPICAL CYCLONE WARNING
TROPICAL CYCLONE ADVICE NUMBER 19
Issued by the BUREAU OF METEOROLOGY, DARWIN
at 11:00 pm CST [9:30 pm WST] Sunday 13 December 2009
A Cyclone WARNING continues for coastal areas from Kuri Bay to Wyndham.
A Cyclone WATCH continues for coastal areas from Kuri Bay to Cape Leveque, not
including Derby.
At 9:30 pm CST [8:00 pm WST] Tropical Cyclone Laurence, Category 1 was estimated
to be 230 kilometres north northeast of Kalumburu and 480 kilometres northeast
of Kuri Bay and moving northwest at 7 kilometres per hour.
Tropical Cyclone Laurence is expected to move west or west southwest parallel to
the north Kimberley coast in Western Australia.
GALES with gusts to 100 kilometres per hour may develop on the north Kimberley
coast during Monday if the cyclone moves closer to the coast.
HEAVY RAIN may develop in the north Kimberley region later on Monday or Tuesday
if the cyclone moves closer to the coast.
FESA-State Emergency Service advises of the following community alerts:
BLUE ALERT: People between Wyndham and Kuri Bay, including the communities of
Wyndham, Oombulgurri, Kalumburu, Mitchell Plateau and Kuri Bay should start
taking precautions.
Details of Tropical Cyclone Laurence at 9:30 pm CST [8:00 pm WST]:
.Centre located near...... 12.5 degrees South 127.7 degrees East
.Location accuracy........ within 95 kilometres
.Recent movement.......... towards the northwest at 7 kilometres per hour
.Wind gusts near centre... 95 kilometres per hour, and slowly intensifying
.Severity category........ 1
.Central pressure......... 998 hectoPascals
The next advice will be issued by 2:00 am CST Monday 14 December[12:30 am WST
Monday 14 December].
My thoughts exactly... practical things work better than paper shuffling.
Physical actions speak louder than word at conferences.
Rained:
AOI
AOI
AOI
AOI
Humor in Comments
Thanks for posting these.
No, not real evident there, is it?
Don't think I would despair just yet Drak. The problems displayed by the GFS during the tropical season are present year round though the manifestation and impact to the pattern is some what different. Points north of a line from Jan-Mgm-Csg-Sav should watch with great interest the events that unfold during Christmas and New Years week. Points further south--west of Jan also. Of course, it is the south, and it is always possible that nothing occurs. Nearby oozing low level arctic air combined with a pattern aloft that supports moisture surges every 4 to 5 days can and probably should lead to some wintry surprises somewhere across the south. It would be different if the cold simply overwhelmed the pattern.
Link
Hope NRAamy's ok.
Any reason why Boothville only got 0.74?
Well south of nearly stationary convergence zone. Lucky bastards ;-)
I know but it is interesting. I looked at the GFSP and it is still calling for snow the day before Christmas across Texas, Louisiana, advecting towards the Panhandle of Florida.
Whoa. If the snow line basically followed the 0 C 850mb line, that would end up being a historic snow event. Maybe not huge, but a solid few inches...
(I hadn't looked at this yet)
1000mb-850mb thickness would have temps around freezing at that point.
It would most likely be a freezing rain or sleet event. That cold air will be rather shallow, especially over eastern areas due to cold air damming.
Yeah, I was thinking NOLA through Mobile, maybe Pensacola...points east, it gets tougher.
Yea, those overunning events are tough to pinpoint. Always some snow along the northern fringes. The deep south always has a better chance at accumulating snow with a cold north or northwest wind which keeps all levels of the atmosphere below 0 C. If that Christmas system pans out, winds will generally be form the NE or E. Still could be a significant event if enough Gulf moisture gets advected in.
12 hours ago, I predicted that in 36 hours there would be six tropical cyclones on the map. Back then, there were only two, and guess what, now there already are five! The only TC yet to form, then, according to my predictions is a tropical storm off southeastern Brazil and Uruguay, as SSTs there have been warming crazily within the past week.
River forecasts are not issued for this river...
Loop
Goodnight all
It's just chilly and rainy here. For those of you trapped in your home and dreaming of SNOW, which IS on their way -- here's a cute, fun, cheap item I found on my e-mail this morning. :)
Sno Storm
Free Style Foam Sled
$ 14. 99 each at ALDI
I am thinking about starting my own blog for inexpensive, practical "green" bargains and to deal with the recession; also items to cope with bad weather and hopefully avert and mitigate disasters. Fun stuff, too!
Any suggestions for a name for my blog?
Other than "Thank G-d She's Off the Main Blog!"
Nah, that's MY specialty. I couldn't even get a "mercy" lol last night! Everyone went zzzzzzzz on me -- imagine that, they had things to do and places to be on a Saturday night!
KingCraft
35" Snowbrush
$ 3. 99 each
Not sure if this one is a truly great price:
KingCraft
Rechargeable LED Worklight
$ 19. 99 each *
And how badly we didn't need the rain. That is quite enough of that:
NWS agrees and it really is the wettest December on record already and it is only the 13 th!
"Not surprisingly...daily rainfall records across the area were broken at several climate sites. For New Orleans...the additional rainfall Saturday and Saturday night was enough to make this December the wettest on record...with 19 days left in the month and additional rainfall forecast for Monday night."
Southern Hemisphere mad
First it tried to freeze me all last week.. and now its frikken snowing :(
That looks like someone folks in the FL Panhandle are gonna have some winter weather. With the SW winds aloft, the warm air advection will probably produce an icestorm, rather than a snowstorm..
I am not going to be happy until it snows on Ike and BF :) ohhh and maybe a smidge for Sarasota :)
Any snow/Ice event is significant down here in the south...LOL
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