Last
night Isaac moved across Haiti dumping torrential rains on the poorest country
in this hemisphere. High winds and
flooding rains pounded the country into the morning hours. The center of Isaac moved across the southern
mountains of Haiti, but then turned northward through the Windward Passage to reach
the eastern tip of Cuba by midday.
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| Click on image to enlarge. Image Credit: NOAA/NHC. |
This
is the latest plot of the path of Isaac with the associated wind field. Notice how erratic the path has been since
moving into the Caribbean. This is due
to the complex weather pattern over the region playing a tug-of-war with the
storm and it is still happening.
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| Enhanced infrared satellite picture for 00:45z August 26, 2012. Image Credit: NESDIS. |
Tropical
Storm Isaac did weaken some going over the mountains in Haiti. However, the central circulation stayed
intact and the storm jogged to the north before turning to the northwest upon
reaching Cuba. It has been moving along
the north coast of Cuba during the afternoon and evening. The interaction with land and kept the
structure and little ragged with no strengthening.
However,
Isaac avoided the mountains in eastern Cuba which could have greatly disrupted
the circulation. There are signs that
the storm will strengthen as it moves away from Cuba. In addition, the steering currents could turn
it more to the west early in the morning pushing more toward Key West. Rain bands are already moving into south
Florida as seen Saturday evening from the Miami NWS radar.
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| NWS radar from Miami at 9:16 p.m. EDT August 25, 2012. Image Credit: NWS |
Computer
simulations have flip-flopped during the past 24 hours. This is true of the ECMWF, GFS, Canadian, and
GFDL models. Those forecasting a
landfall in the lower Mississippi River Valley yesterday were pointing to the
Florida panhandle today and vice versa.
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| The ECMWF forecast for 12z on August 24 and 25, 2012. Image Credit: WSI. |
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| The GFS forecast for 12z August 24 and 18z August 25, 2012. Image Credit: WSI. |
What
does this mean?
The
simulations are having a hard time resolving the patterns that would ultimately
steer the storm. There is much
uncertainty once the storm moves into the northern Gulf of Mexico. Forecasters at the National Hurricane Center
are having a hard time with the extended range forecast track and an even
harder time with the forecast intensity.
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| The 5-day forecast for Isaac at 11 p.m. EDT August 26, 2012. Image Credit: NOAA/NHC. |
Do
not be concerned much for the centerline track.
In this storm it has been of little use except to me. The cone of uncertainty has been a better
guide with the storm rarely being outside of it since forming. This part of the forecast path has been good.
Bottom-line:
Residents along the northern Gulf coast need to take this seriously. There is a possibility for a major hurricane
hitting the area by Tuesday. Even if it
doesn’t get that strong, there will be a considerable storm surge. Heavy rain will be likely inland as the system
slows down. The path after that remains
unclear.
I’ll
have another look at the storm late Sunday.
