Unprecedented late October storm track from Hurricane Sandy this week
Only the 2nd Hurricane to ever hit New Jersey
“Blocking pattern” steered Sandy in unusual NW direction into Jersey Shore
Warmer arctic linked to more frequent jet stream blocking patterns
Record Arctic Sea Ice loss in 2012 may have enhanced blocking pattern this fall
Warmer waters caused Sandy’s “intensity flare” just before landfall
Image: ABC6 News
What just happened? Connecting the dots
We’ve just witnessed a massive hurricane that did something no other tropical system has done in the past – Make a sharp left turn in the Atlantic and plow headfirst into New Jersey & New York in late October.
Here’s why Sandy’s track was unprecedented for a hurricane this late in the tropical season.
-Late October jet streams are usually well established far enough south that any northward moving Atlantic hurricanes are pushed eastward into the Atlantic by fast moving jet stream winds before they reach the East Coast.
-According to Jeff Masters of WxUndeground, Sandy is just the 2nd hurricane to ever hit the relatively protected (recessed) Jersey Coast. The only other hurricane to hit New Jersey was the “Vagabond Hurricane” in 1903, and that one hit in September when the jet stream is usually further north.
For nearly 2 weeks now I’ve talked and written about the unusual jet stream pattern that “sucked” sandy back to the NW and into the Jersey Shore.
Source: Climate Central
In weather geek speak we call these highly amplified jet stream patterns “blocking patterns” because they force the jet stream to meander into big north-south kinks and loops…instead of flowing more rapidly from west to east.
Blocking patterns have always formed in certain seasons, but tend to become less common in fall…only about 2% of the time vs. 6% in winter & spring.
There is a growing body of evidence that blocking patterns may be increasing as the Arctic warms. The blocking pattern this week over Greenland, combined with a “negatively tilted” (backwards leaning) low pressure trough over the eastern USA sucked Sandy back to the NW at the last minute into New Jersey, instead of shoving her out to sea.
-That produced less “pole to equator” temperature contrast between the Arctic and lower latitudes.
-North to south temperature contrasts are what drive the jet stream
-The lower temperature contrast produced a weaker, more meandering jet stream for late October…and an unusually strong blocking pattern developed.
-The block created a kink in the jet stream that allowed Sandy to be sucked back to the NW into the Jersey Coast.
-Warmer than average ocean temps along the Gulf Stream caused Sandy to burst with an unusual “intensity flare” just off the Coast…delivering a stronger, more destructive storm at landfall.
Sandy’s unprecedented storm track suggests climate change may be be affecting basic weather patterns in a way that’s rewriting many of the things we used to call “Meteorology 101.”
More research will undoubtedly be done to close the potential link between a warmer Arctic and Sandy’s unprecedented path of destruction.
In the mean time, residents of the East Coast are less concerned with why Sandy hit, as they struggle to survive her devastating aftermath.