Debunked: Weatherwar101 - Hurricane Iselle Disintegration

solrey

Senior Member.
Weatherwar101 claims that Hurricane "Iselle clearly slams into a frequency wall, and is instantly destroyed."


Iselle did indeed slam into a wall, a 13,000 foot wall called Mauna Loa, and another called Mauna Kea. WW101's so called "frequency wall" was a lee wave cloud produced by the northwesterly component of the wind field blowing over the volcano. Iselle had weakened considerably due to wind shear as it approached Hawaii and was downgraded to a tropical storm prior to making landfall. The terrain of the island (Mauna Loa/Mauna Kea) disrupted the cyclonic circulation causing Iselle to weaken to a tropical low. The remnant tropical low triggered a few storms as it passed to the south of the island chain.

TROPICAL STORM ISELLE DISCUSSION NUMBER 35
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP092014
1100 AM HST FRI AUG 08 2014

INTERACTION WITH THE BIG ISLAND VOLCANO SUMMITS APPEARS TO HAVE
DONE QUITE A NUMBER ON ISELLE THIS MORNING.
Content from External Source
http://www.prh.noaa.gov/cphc/tcpages/archive/2014/TCDCP3.EP092014.035.1408082030

The mountainous terrain of the island largely disrupted the main cyclonic circulation of Iselle, which manifested as a collection of small vorticies south of the Hawaiian islands.
Content from External Source
http://en.wikipedia.org/wiki/Hurricane_Iselle_(2014)

Those small vortices are known as vortex streets:

Under favorable conditions, when stratified air flows around an obstacle such as a mountain or an island, atmospheric vortex streets (AVS) or atmospheric gravity waves (AGW) often develop around the obstacle.
Content from External Source
http://www.sarusersmanual.com/ManualPDF/NOAASARManual_CH16_pg341-354.pdf

The complex winds in the cyclonic circulation around the central low produced both vortex streets and a gravity wave.

No need to invoke an imaginary "frequency wall" when a tropical storm encounters two of the largest volcanoes in the world.

http://www.nasa.gov/content/goddard/iselle-eastern-pacific-ocean/#.U_OfQa5ncmU

http://en.wikipedia.org/wiki/Mauna_Loa

http://en.wikipedia.org/wiki/Mauna_Kea

http://en.wikipedia.org/wiki/Orographic_lift

http://twister.ou.edu/QJ/CD1-1971-1980/1978/v104n442/s6.pdf

http://onlinelibrary.wiley.com/stor...2o&s=65794b03eb0c2d72ff34a83b09e0e4b656ce8008
 

BigTBoom

New Member
Hurricane Flossie was influenced in a similar way as it moved by the Big Island in 2007.

There is also a fair amount of research published about Taiwan's orographic effecting approaching typhoons in a similar fashion.
 

BigTBoom

New Member
The up slope clouds formed on the northeast/windward side of the island as Iselle approaches is an interesting demonstration of the volcanoes orographic influence on the flow over/around the island. The southwestern side of the volcanoes (beginning around 1:03) remain relatively cloud free zone clear of clouds is present in the visible satellite as the storm approaches.
It would be interesting to see a temperature record in the valley between Mauna Kea and Mauna Loa to see if there was any warming and/or drying occurred as the result of a down slope / foehn type wind, something which has been observed and researched on Taiwan (http://journals.ametsoc.org/doi/pdf/10.1175/2009JAMC2070.1).
 
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