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October 19, 2005

Keeping an Eye on Hurricane Wilma

Carroll Andrew Morse

Greetings to readers from outside of New England! These updates are targeted to the concerns of New Englanders, and the times and events cited may not be relevant to hurricane preparations elsewhere. Please consult the National Hurricane Center for the most up to date nationwide information.

This is from the 11 AM discussion of Hurricane Wilma from the National Hurricane Center

THERE HAS BEEN LITTLE CHANGE TO THE FORECAST TRACK THROUGH 96 HOURS. HOWEVER...RECENT RUNS OF THE GFS AND NOGAPS ARE SUGGESTING THE POSSIBILITY OF A THREAT TO NEW ENGLAND. IN THIS SCENARIO...WILMA BECOMES CAPTURED BY A LARGE MID- TO UPPER-LEVEL LOW FORECAST TO MOVE INTO THE GREAT LAKES REGION IN FOUR DAYS. THE ECMWF AND IN PARTICULAR THE UKMET...BOTH OLDER RUNS...DO NOT YET INDICATE THIS. THE FIVE-DAY OFFICIAL FORECAST POINT HAS BEEN ADJUSTED TO THE LEFT AND FASTER THAN THE PREVIOUS ADVISORY...BUT IS STILL MUCH FARTHER OFFSHORE OF NEW ENGLAND THAN THE GFDL...GFS...AND NOGAPS GUIDANCE.
Those funny strings of letters, like GFS, NOGAPS, ECMWF, etc. are the names of different computer models that predict the storm track. The forecaster looks at all the different models, and then uses his judgment and experience to make the official forecast.

Here’s the map of the current forecast track. According to the forecast, there is still a strong possibility that Wilma will stay out to sea (from a New England perspective). But look how quickly the storm moves from the Carolina coast (projected Sunday morning) to the New England coast (projected Monday morning).

Why am I bringing this up now? A short time ago, I proposed a disaster preparation template. One question to be addressed was…

2. What mistakes are citizens preparing for a disaster likely to make? How do we deliver the information and resources that will help people preempt as many of their own errors as possible?
A major danger associated with Wilma is that people may not realize how quickly a hurricane can move up the Atlantic coast. On Sunday morning, they may hear that the storm is off the coast of North Carolina, assume that they still have 3 or 4 days to prepare (especially after the behavior of Ophelia, which meandered off of the Mid-Atlantic coast for several days), and wait too long to evacuate.

Local weather forecasters and emergency authorities need to make clear the necessity of planning around Wilma’s forecast track as soon as Wilma passes into the North Atlantic.

UPDATE:

5PM update from the National Hurricane Center says there is great uncertainty in Wilma’s forecasted track…

AGREEMENT AMONG THE TRACK GUIDANCE MODELS...WHICH HAD BEEN VERY GOOD OVER THE PAST COUPLE OF DAYS...HAS COMPLETELY COLLAPSED TODAY. THE 06Z RUNS OF THE GFS...GFDL...AND NOGAPS MODELS ACCELERATED WILMA RAPIDLY TOWARD NEW ENGLAND UNDER THE INFLUENCE OF A LARGE LOW PRESSURE SYSTEM IN THE GREAT LAKES REGION. ALL THREE OF THESE MODELS HAVE BACKED OFF OF THIS SOLUTION.…WHAT THIS ILLUSTRATES IS THE EXTREME SENSITIVITY OF WILMA'S FUTURE TRACK TO ITS INTERACTION WITH THE GREAT LAKES LOW....SUBSTANTIAL CHANGES TO THE OFFICIAL FORECAST MAY HAVE TO BE MADE DOWN THE LINE. NEEDLESS TO SAY...CONFIDENCE IN THE FORECAST TRACK...ESPECIALLY THE TIMING...HAS DECREASED CONSIDERABLY.
The uncertainty makes it all the more important for Rhode Islanders to be aware of Wilma’s position. Once the storm crosses Florida and enters the North Atlantic, whenever it does (current forecast is Sunday afternoon), it may only be 24-36 hours until it moves up here.

Comments

Andrew,

Hurricanes draw their strength from the waters below them. Do you know how strong could Wilma be if/when she reached the New England area?

Posted by: don roach at October 19, 2005 3:42 PM

Don,

The NHC predicts winds speeds of 80-90 knots 96-120 hours from now. That’s a category 1, which means wind damage wouldn’t be extreme, BUT with the ground already well saturated, damage from flooding might be severe.

I believe that intensity forecasting is a much more uncertain business than position forecasting, and that the intensity forecast will almost certainly change as the storm moves closer.

Posted by: Andrew at October 19, 2005 4:23 PM

i want to know if wilma is going to be here tomorrow or by monday because i have herd from channels 4,7,10 and 51 and 23 and all the metereologist say different things i'm sort of lost because of what i herd from channel 7 were going to start feeling the effects tomorrow but the real thing is coming on monday and when i change channel the other says another thing.

Posted by: SHEILA at October 22, 2005 11:01 AM

Shelia,

I can't tell what part of the world you are in from your posting, so let me give you the link to the National Hurricane Center -- www.nhc.noaa.gov

If you check the 5-day forecast map, you will see that the current forecast is that Wilma hits the west coast of Southern Florida on Monday morning. But remember, hurricanes are large systems; people in the storm's path will feel its effects long before the center arrives. Southern Florida will probably start to experience Wilma effects on Sunday evening.

Posted by: Andrew at October 22, 2005 12:24 PM