Arctic sea ice melting season begins
The annual Arctic melting season has begun. We've just passed the Spring Equinox, so the North Pole is now in 24-hour daylight. Will the melting of Arctic sea ice this year surpass last year's record? Well, we have a greater areal extent of ice over the Arctic this month compared to April of last year, thanks to some cool Arctic temperatures this winter. In particular, the ice in the Bering Straight between Alaska and Russia extends quite a bit further south than in 2007. This extra ice will likely delay the melting season a bit this year, giving some hope that we won't surpass last year's record melt. However, if weather similar to last summer occurs--unusually clear skies and high pressure over the Arctic--this extra ice will not help much, because it is all thin, first-year ice. It is the thick, 2-9 year old ice that is most able to resist summer melting, and the amount of old multi-year ice is only about half of what it was in 2007. This is apparent from images taken by the QuikSCAT satellite, which carries the SeaWinds scatterometer. This instrument emits a pulse of microwave energy that bounces off the ice and returns to the satellite. Old, multi-year ice is thicker, and reflects a different amount of microwave energy back to the satellite than thin ice, resulting in a whiter image. Thin, first-year ice appears a darker grey. It is apparent from Figure 1 that we have only about half of the old, multi-year ice that we had last year. In fact, thin first-year ice extends past the North Pole, raising the distinct possibility that this year's melt will allow one to sail a ship all the way to the North Pole in September, for the first time since humans began testing Arctic waters with ships in 1497. In addition, a large region of the old ice north of Alaska is highly fractured, making it vulnerable to melting.
Figure 1. QuikSCAT images of the Arctic from April 4, 2007 and April 4, 2008. The boundary of old, multi-year ice is marked in yellow, and 2008 has about half the old ice of 2007. Image credit: NOAA/NESDIS/ORA.
How did we lose so much old ice in the past year?
Part of the lost old ice melted during the record-breaking melt season of 2007, which was fueled both by global warming and a natural (but unusual) sunny summer. Another big chunk of old ice was lost due to natural wind patterns between September 2007 and March 2008. An animation of the sea ice available from Environment Canada's sea ice page (click on "Updated QuikScat animation") reveals that strong winds pushed large amounts of old ice out of the Arctic southward along the east coast of Greenland. So, we can't blame the melting of the Arctic sea ice entirely on global warming--natural weather patterns also played a significant role.
The forecast
It's impossible to guess what the dominant Arctic weather pattern will be this summer, and what level of melting we will get. With the loss of so much old ice over the past year, though, even an average summer has the potential to melt much more ice this summer compared to last summer--all the way to the North Pole. There's also a good chance that we'll see the fabled Northwest Passage open up again, since most of the ice along the Passage is young, first-year ice. We'll just have to wait and see how the summer unfolds.
Jeff Masters
Reader Comments
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morning all. Anyone know the history of hurricane landfalls near Tampa, Fl.? I got into a dispute..Some Tampa residents seem to think they wont get a storm with winds over 60mph... I think thats just silly.
Thanks again.
I can't find it right now but there is an older NWS chart (through 2001) which has all the hurricane strikes on Florida charted, going back to about the 1940's, and the Tampa area is pretty "light" on the map.....The most heavy area of strikes, on the Southern end of FL is from Naples around to Miami/FT. Lauderdale/Palm Beach, and, in the Florida Panhandle from Panama City area westward......The relative "safe zones" for Florida does seem to be from Tampa to the Big Bend on the West Coast, and, from Palm Beach to Jacksonville on the East Coast....
Florida Hurricane Strike Probability Statistics
Hurricane strike probabilities are only statistical estimates.
Pensacola 1 in 8
Apalachicola 1 in 17
Tampa 1 in 25
Ft. Myers 1 in 11
Key West 1 in 8
Miami 1 in 6Palm Beach 1 in 7
Vero Beach 1 in 20
Melbourne 1 in 20
Daytona Beach 1 in 50
Jacksonville 1 in 100
Notice how Miami area has been the most prone in Florida and how Jacksonville has been the least prone........
This product will be produced for all storms this season.
From email:
"PUBLIC INFORMATION STATEMENT...COMMENT REQUEST
NATIONAL WEATHER SERVICE HEADQUARTERS WASHINGTON DC
1030 AM EDT WED APR 9 2008
TO: SUBSCRIBERS:
-FAMILY OF SERVICES
-NOAA WEATHER WIRE SERVICE
-EMERGENCY MANAGERS WEATHER INFORMATION NETWORK
OTHER NWS PARTNERS...USERS AND EMPLOYEES
FROM: THERESE Z. PIERCE
CHIEF...MARINE AND COASTAL SERVICES BRANCH
SUBJECT: SOLICITING COMMENTS FOR EXPERIMENTAL TROPICAL
CYCLONE WIND FIELD GRAPHIC THROUGH NOVEMBER 30 2008
BEGINNING MAY 15 2008 AND CONTINUING THROUGH NOVEMBER 30 2008
... NWS IS SEEKING USER FEEDBACK ON AN EXPERIMENTAL TROPICAL
CYCLONE WIND FIELD GRAPHIC.
THIS PRODUCT WILL BE PRODUCED WITH EACH FULL ADVISORY PACKAGE FOR
TROPICAL AND SUBTROPICAL CYCLONES IN THE ATLANTIC AND EASTERN
PACIFIC HURRICANE BASINS. THIS GRAPHIC ILLUSTRATES THE AREAS
POTENTIALLY BEING AFFECTED BY TROPICAL CYCLONE SUSTAINED WINDS OF
VARYING FORCE.
IN ADDITION TO THE WIND FIELD THE GRAPHIC SHOWS AN APPROXIMATE
REPRESENTATION OF COASTAL AREAS UNDER A HURRICANE WARNING...
HURRICANE WATCH...TROPICAL STORM WARNING AND TROPICAL STORM
WATCH. A WHITE DOT INDICATES THE CURRENT POSITION OF THE CENTER
OF THE TROPICAL CYCLONE AND THE DASHED BLACK LINE SHOWS THE
HISTORY OF THE CENTER OF THE TROPICAL CYCLONE.
DURING PERIODS OF ACTIVE STORMS THE PRODUCT WILL BE ONLINE AT:
/USE LOWER CASE LETTERS/:
HTTP://WWW.NHC.NOAA.GOV/
A COMPREHENSIVE DESCRIPTION AND EXAMPLE IS POSTED AT:
/USE LOWER CASE LETTERS/:
HTTP://WWW.NHC.NOAA.GOV/ABOUTNHCGRAPHICS.SHTML#INITIALWIND
USERS ARE ENCOURAGED TO PROVIDE FEEDBACK ON THIS EXPERIMENTAL
PRODUCT BY USING THE BRIEF SURVEY AND COMMENT FORM AVAILABLE AT
/USE LOWER CASE LETTERS/:
HTTP://WWW.WEATHER.GOV/SURVEY/NWS-SURVEY.PHP?CODE=TWFG
A LINK TO ALL NHC EXPERIMENTAL PRODUCTS IS ALSO PROVIDED AT
/USE LOWER CASE LETTERS/:
HTTP://WWW.NHC.NOAA.GOV/ABOUTEXPERIMENTAL.SHTML
"
The strike probabilities do not include that tidbit...
As a matter of factual data, in the 151 yr history of hurricanes ther has NEVER been a MAJOR hurricane (Cat III or greater) make a landfall north of Fort Pierce,FL or south of Savannah, GA.
The strike probabilities do not include that tidbit...
New Orlenes "We never get any damage from Hurricanes, they never hit there." It can happen, Hurricanes can hit anywere on the US coast, from Maine to Texas.
Link
15 Named Storms
80 Named Storm Days
8 Hurricanes
4 Intense Hurricanes
ACE 150.
With a higher risk for Landfall in the US than last year.
As a matter of factual data, in the 151 yr history of hurricanes ther has NEVER been a MAJOR hurricane (Cat III or greater) make a landfall north of Fort Pierce,FL or south of Savannah, GA.
The strike probabilities do not include that tidbit...
I have no idea if there is any scientific basis for it (or merely a matter of geometry/trajectory analysis in terms of when, and from where, storms approach the SE US coast) but I am intrigued by the fact that the majority of storms seem to follow "the curve" of the Florida Big Bend in the Gulf, or, the "the curve" from Mid-Florida up through the Carolinas before they are taken inland (to parts West of Panama City or parts North of Savannah)..........
Australian storm?
Yes, and I can't wait... it's been pretty dry here (in Barbados)...
5 Current Atlantic Basin Conditions
Current conditions in the Atlantic basin are quite favorable for an active hurricane
season. Both of our early April predictors call for a very active hurricane season in 2008.
The current sea surface temperature pattern in the Atlantic is a pattern typically observed
before very active seasons. Waters off the coast of Iberia as well as the eastern tropical
Atlantic are very warm right now (Figure 6). The Azores High has also been quite weak
during the month of March. Typically, a weakened Azores High leads to weaker trade
winds that enhance warm SST anomalies due to reduced levels of evaporation, mixing
and upwelling in the eastern tropical Atlantic.
Our final April statistical model calls for a hyper-active season with an NTC of
190 (Table 10). Due to the uncertainty with current ENSO conditions, we do not feel
confident enough to raise our forecast that high at this point, however, if current trends in
the Atlantic persist, there is a possibility that the forecast could be increased more in early
June.
Yikes!!!
My forecast for the 2008 Atlantic hurricane season - Issued March 10th.
2. I've raised my forecast dramatically. From 3 tropical storms to 13, and from 0 hurricanes to five.
3. If the Bermuda High swings too far east we might see all fish storms again...ONOZ!
4. StormTOP/StormKat won't be here this hurricane season, because he died.
5. AWL is VERY hot.
6. I'm going to a basketball game tonight, so I won't be around.
1. The Carolinas
2. Texas
3. New England
4. Puerto Rico
5. Florida
6. Hispaniola
7. Cuba
8. Mexico
9. Leeward Islands
10. Central america
11. Jamaica
12. Gulf Coast
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