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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I hope you all are doing well and getting prepared for the season ahead!
Current Conditions
Uptown, New Orleans, Louisiana (PWS)
Updated: 27 sec ago
Scattered Clouds
85.3 °F / 29.6 °C
Scattered Clouds
Humidity: 30%
Dew Point: 50 °F / 10 °C
Wind: 2.2 mph / 3.5 km/h / 1.0 m/s from the ESE
Wind Gust: 2.7 mph / 4.3 km/h
Pressure: 29.97 in / 1014.8 hPa (Falling)
Great! now that i'm looking at the sat. link hurricane posted I can see that most of the complex in the gulf will pass well to the south of tampa. Maybe I can have a bonfire tomorrow after all
The timing of the system is very sketchy and the shear will have time to play around with it. It looks as though the concentrated activity is to the south.
Squall line that came through last night!
Really impressive line of strong storms.
DRAWN TO THE TSTM COMPLEX OUT IN THE CENTRAL GULF ATTM. WATER VAPOR
CLEARLY SHOWS A NICE MID LEVEL SHORT WAVE ASSOC WITH THIS COMPLEX...
AND WHILE GFS AND NAM BOTH HAVE THIS FEATURE...THEY DIFFER ON
DETAILS. FIRST OFF...NAM INITIALIZED THE MOISTURE FIELD TOO FAR
SOUTH...BUT HOLDS THE SHORT WAVE TOGETHER AND TAKES IT ACROSS THE
SOUTHERN THIRD OF THE PENINSULA LATER TONIGHT AND EARLY TUESDAY.
THE GFS DID A BETTER JOB INITIALIZING THE MOISTURE FIELD...BUT
THEN SEEMS TO SUFFER FROM CONVECTIVE FEEDBACK SHORTLY INTO THE
RUN...WITH EFFECTS ON THE SHORT WAVE. AS SUCH...WE HAVE LOW
CONFIDENCE IN BOTH GFS AND NAM SOLUTIONS WITH THIS COMPLEX. SAT
TRENDS SUGGEST THAT AT LEAST OUR SOUTHERN MOST ZONES MAY HAVE A
CHANCE TO GET SOME LIGHT RAIN FROM SHOWER ACTIVITY ON THE OUTER
PERIPHERY OF THIS SYSTEM...AS IT SKIRTS BY TO OUR SOUTHWEST LATE
TONIGHT AND EARLY TUESDAY. CAN`T RULE OUT THAT IT MOVES FARTHER
EAST GIVING MORE OF OUR CWA A CHANCE FOR RAIN...BUT FOR NOW WILL
KEEP POPS LIMITED TO OUR SOUTHERN ZONES NEAR FORT MYERS (20 PCNT
TONIGHT). NEEDLESS TO SAY...WATCHING THIS ONE CLOSELY!
OTHERWISE...OUR FAR NORTHERN ZONES STILL SEEING SOME LOW CLOUDS
THANKS TO COOL MOIST NE FLOW. ALTHOUGH CLOUDS CONTINUE TO BREAK
THIS AFTERNOON...NE FLOW AND COOLER AIR WILL SET THE STAGE FOR
SOME PATCHY FOG TONIGHT...MAINLY TAMPA BAY NORTH.
I will be back when i lift my head up off the keyboard and delete all the letters that get typed repeatedly as I pass ouuuuuuuuuuuuuuuuuuuuuu
10% chance of significant tornadoes (>EF2) within 25 miles of any given point within the hatched area.
45% percent probability of large hail (2" or larger) within 25 miles of the hatched area.
15% percent probability of high winds (>50 knots).
The "hatched area" mentioned above encompasses most, if not all of the moderate risk area shown below.
Note how small the moderate risk section is...I guess they're especially confident about where the severe weather will occur. At the approximate center is Lawton, OK where I hear many of the storm chasers are currently heading. Eevn now that there is a moderate risk the SPC is still mentioning that there is the possibility for an even greater risk of tornadoes to develop than currently is anticipated.
Conditions are very favorable, with 3000 L/kg CAPE (very conductive for supercell development) with an area of Helicity of over 400 (very conductive for tornadoes, specifically) now moving into Oklahoma from the west. Currently, EHI (Energy Helicity Index) is in the positive values (0.0 - 0.2) in Oklahoma and is on the rise. Currently, EHI would support weak tornadoes; however, if the value rises above 1.0, EF2 to EF3 tornadoes would be possible. BRN (Bulk Richardson Number) last time I checked was still in the single digits but had risen since the previous air sounding. If BRN rises into the teens, this would indicate optimum conditions for supercell activity.
Wow...probability of 2 or more tornadoes within the watch area is more than 90%.
...THIS IS A PARTICULARLY DANGEROUS SITUATION...
DESTRUCTIVE TORNADOES...LARGE HAIL TO 4 INCHES IN DIAMETER...
THUNDERSTORM WIND GUSTS TO 80 MPH...AND DANGEROUS LIGHTNING ARE
POSSIBLE IN THESE AREAS.
LOL (good question) :p
That Blob is looking like two eyes and a nose, or, some other anatomical parts I dare not mention right about now on the Sat loops....
LOL.
The gulf certainly looks interesting and I must say that my husband sure picked a bad week to spend time in north Texas. Aren't there supposed to be more severe storms in N TX toward the weekend?
Any input on the MCS in the gulf? Timing, location?
Its just been sitting there slowly moving to the east. The models haven't initialized it we we are just waiting it out in Florida.
Thanks for the input Drak. I'm hoping for some more bonus rain in the dry season here in SEFL.
No problem. The concentrated activity is to the south so South Florida should get in on some of it.
!!!THIS IS NOT A DRILL!!!
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