Hurricane BERTHA

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HURRICANE BERTHA DISCUSSION NUMBER  17
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL032014
1100 PM EDT MON AUG 04 2014

Bertha certainly does not look like a typical hurricane in satellite
imagery this evening.  The center has become partially exposed to
the northwest of the deep convection.  A NOAA Hurricane Hunter
aircraft that recently investigated the cyclone observed
flight-level, SFMR, and dropsonde winds that all supported hurricane
intensity late this afternoon.  Since that time, the organization
has degraded a little and it is possible that Bertha has weakened
below hurricane strength.  However, new convection has recently
formed just east of the center near where the strongest winds were
measured earlier.  Therefore, the initial intensity is held at 65
kt. This could be generous, but it is best to maintain hurricane
status until the the next Hurricane Hunter aircraft examines the
storm around 0600 UTC.

Bertha is forecast to gradually weaken during the next day or two
while it moves into an area of increasing southwesterly vertical
wind shear and over decreasing sea surface temperatures.  On
Wednesday, the cyclone is expected to interact with an approaching
mid-latitude trough and Bertha is forecast to become an
extratropical cyclone over the North Atlantic shortly thereafter.

Fixes from the aircraft show that Bertha is moving a little faster
and has turned north-northeastward this evening. The track forecast
reasoning remains unchanged. Bertha is expected to accelerate
northeastward during the next day or two between a mid-level ridge
over the western Atlantic and a deep-layer trough moving off the
northeast United States coast.  After Bertha becomes a post-tropical
cyclone in 48 to 72 hours, it is forecast to turn east-northeastward
in the mid-latitude westerly flow over the north Atlantic.


FORECAST POSITIONS AND MAX WINDS

INIT  05/0300Z 31.3N  73.1W   65 KT  75 MPH
 12H  05/1200Z 33.7N  71.9W   60 KT  70 MPH
 24H  06/0000Z 36.6N  68.8W   60 KT  70 MPH
 36H  06/1200Z 39.3N  64.2W   55 KT  65 MPH
 48H  07/0000Z 42.1N  58.9W   55 KT  65 MPH
 72H  08/0000Z 47.5N  47.0W   45 KT  50 MPH...POST-TROP/EXTRATROP
 96H  09/0000Z 48.5N  31.0W   45 KT  50 MPH...POST-TROP/EXTRATROP
120H  10/0000Z 49.5N  15.0W   45 KT  50 MPH...POST-TROP/EXTRATROP

$$
Forecaster Brown

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