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HURRICANE ALEX DISCUSSION NUMBER 6
NWS NATIONAL HURRICANE CENTER MIAMI FL AL012016
1100 PM AST THU JAN 14 2016
Satellite imagery indicates that the convective structure of Alex
has decayed during the past 6 hours, with the eyewall breaking
open and the banding dissipating in the southeastern semicircle.
Based on this, the initial intensity is lowered to 70 kt. The
hurricane is moving over colder sea surface temperatures of less
than 20C. However, the cyclone should begin extratropical
transition in the next few hours, and the global models suggest
there will be enough baroclinic forcing to maintain hurricane-force
winds through and after the transition despite the cold water.
Based on this and input from the Ocean Prediction Center, the new
intensity forecast shows little change in strength until Alex is
absorbed by a large extratropical low in about 72 hours.
The initial motion is 010/19. There are no changes to the forecast
philosophy from the previous advisory and only minor tweaks to the
forecast track. Alex continues to be steered by the flow of a
shortwave mid-tropospheric trough that is rotating around the
developing large baroclinic low to its west and northwest. This
evolution should cause the cyclone to turn gradually to the left
with increasing forward speed over the next couple of days. The
dynamical track guidance models remain in excellent agreement for
the first 36 hours of the forecast, and the official forecast is
near the model consensus.
Alex's wind field is likely to expand as it undergoes extratropical
transition. The wind radii forecasts are based primarily on
guidance from the NOAA Ocean Prediction Center.
FORECAST POSITIONS AND MAX WINDS
INIT 15/0300Z 34.7N 27.6W 70 KT 80 MPH
12H 15/1200Z 38.4N 27.8W 65 KT 75 MPH
24H 16/0000Z 45.0N 29.1W 65 KT 75 MPH...POST-TROP/EXTRATROP
36H 16/1200Z 52.7N 32.1W 65 KT 75 MPH...POST-TROP/EXTRATROP
48H 17/0000Z 59.0N 37.0W 65 KT 75 MPH...POST-TROP/EXTRATROP
72H 18/0000Z...ABSORBED BY EXTRATROPICAL LOW