Sunday, August 26, 2012

NEW GFS Brings 2x More Rain to New Orleans Than Katrina

If the new GFS were to verify, Hurricane Isaac could bring 2 TIMES MORE rain to New Orleans than Katrina did. Looking at the graphic above, we see that there were a few instances of 7.0 to 9.9 inches of rainfall where Katrina made landfall on the left graphic. There are only a couple reports of 10.0 to 16.3 inches immediately along the Gulf Coast where Katrina made landfall.

On the right graphic is a total precipitation map until Hour 93 of the new GFS. It shows over 12 inches hitting much of southeast Louisiana, with a maximum amount of just over 20 inches shown on the extreme bottom right corner of the image.

If the levees keeled over in 2005 with Katrina due to 10 inches of rain (among other factors), imagine what 20 inches of rain in a large Category 2-3 hurricane could do.

I am not saying this will happen, this is only meant as a comparison and should be treated as such.



Anonymous said...

Hey Andrew, did you see what picture the HWRF is painting.... pretty scary for New Orleans...

- RW

WinterStorm said...

Hi Andrew! I know that this is off topic with all of the talk about Isaac, but the Farmer's Almanac Winter Forecast is out! Here it is: Farmer's Almanac Winter Forecast

Looks good for me in SE Michigan in terms of cold and snow! Can't wait for winter:-) Have a good evening!

Andrew said...

It certainly would be nice if that forecast panned out- I'm waiting for a good snowstorm myself!

ERN WX said...

WinterStorm, I like that outlook!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Just I would move the Cold Snowy area SE. We need a storm that dumps 2 feet of snow each!!!!!!!!!!!

WinterStorm said...

How about another January 25-27 Blizzard of 1978? Blizzard of 1978

And to heighten the winter spirit, a few predictions from the Farmer's Almanac:

November: 4th-7th: "Stormy, especially Great Lakes, where snow is possible. Then clearing, colder."

November 28th-30th: "Unsettled weather, with snow, especially Great Lakes"

December 4th-7th: " Turning unsettled, especially Wisconsin, northern Illinois, where heavy wet snow may fall."

December 20th-23rd: "Snow across Midwest, then fair, very cold."

ERN WX said...

WinterStorm, that sounds cheerful in this time of gloom. Isaac is very bad.

WinterStorm said...

ERN WX, this truly is a gloomy time. I really hope that people evacuated, especially the places that aren't protected by levees. 30-40 inches in 48 hours? That will cause monumental flooding. The NHC should have upgraded Isaac to a hurricane with last night's 11pm advisory. More people would have evacuated because of a Hurricane rather than a Tropical Storm.