Hurricane CRISTOBAL

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HURRICANE CRISTOBAL DISCUSSION NUMBER  21
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL042014
500 PM AST THU AUG 28 2014

The satellite presentation of Cristobal looked its best in visible
imagery shortly after the release of the previous advisory, when the
eye became more apparent.  Since that time, the eye has become a
little more ragged, but a blend of the latest subjective and
objective Dvorak intensity estimates yields an initial wind speed
of 70 kt.  Although the official forecast does not explicitly show
any additional intensification, there is a small window of
opportunity this evening for the hurricane to get a little
stronger.  After that time, Cristobal will be moving across the
north wall of the Gulf Stream -- and over much colder waters.  An
upper-level trough and cold front approaching the cyclone from the
northwest should cause Cristobal to transform into an extratropical
cyclone on Friday.  The extratropical cyclone is expected to
continue to produce hurricane-force winds during the next couple of
days before it merges with another large extratropical cyclone over
the north Atlantic in about 3 days.

The hurricane continues to accelerate, and is now moving
east-northeastward at 31 kt.  The cyclone should continue to
accelerate tonight and remain on an east-northeastward to
northeastward heading during the next 2 to 3 days.  The updated NHC
track is in good agreement with the tightly clustered guidance,
but the forecast has been adjusted slightly to the right due to a
more eastward 1800 UTC initial position.  The track, intensity and
wind radii forecasts of the extratropical low have been coordinated
with the Ocean Prediction Center.

FORECAST POSITIONS AND MAX WINDS

INIT  28/2100Z 38.5N  61.5W   70 KT  80 MPH
 12H  29/0600Z 41.0N  54.7W   70 KT  80 MPH
 24H  29/1800Z 45.2N  46.0W   70 KT  80 MPH...POST-TROP/EXTRATROP
 36H  30/0600Z 49.3N  38.4W   70 KT  80 MPH...POST-TROP/EXTRATROP
 48H  30/1800Z 54.0N  31.0W   65 KT  75 MPH...POST-TROP/EXTRATROP
 72H  31/1800Z 62.0N  23.5W   60 KT  70 MPH...POST-TROP/EXTRATROP
 96H  01/1800Z...MERGED WITH ANOTHER EXTRATROPICAL LOW

$$
Forecaster Brown

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