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HURRICANE ALEX DISCUSSION NUMBER 5
NWS NATIONAL HURRICANE CENTER MIAMI FL AL012016
500 PM AST THU JAN 14 2016
Alex has been maintaining a fairly impressive appearance on
satellite imagery, with a well-defined 15-20 n mi diameter eye
embedded within cold cloud tops. Recent images do suggest some
warming/erosion of the tops over the southwest quadrant. Dvorak
T-numbers remain near 4.5 so the current intensity is held at 75
kt. Sea surface temperatures are now below 20 deg C and should
continue to cool along the path of Alex. This, along with a little
increase in southwesterly shear, should result in gradual
weakening. However, Alex is expected to maintain hurricane strength
while passing near or over the Azores. In 24 hours or so, the
global models show a distinct warm front over the northeast portion
of the circulation. This suggests extratropical transition, and the
official forecast reflects this. Later in the forecast period, the
global models show the system merging with another extratropical
cyclone over the northern Atlantic.
The initial motion is slightly east of due northward or 015/19.
There is essentially no change to the track forecast reasoning.
Alex continues to be steered by the flow of a shortwave
mid-tropospheric trough that has been rotating around a broader
trough to its 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 are
in excellent agreement for the first 36 hours of the forecast, and
the official forecast is near the consensus of these models. This
is basically an update of the previous NHC track prediction.
Alex's wind field is likely to expand as it nears and makes the
extratropical transition. The wind radii forecasts are based
primarily on guidance from the NOAA Ocean Prediction Center.
FORECAST POSITIONS AND MAX WINDS
INIT 14/2100Z 33.6N 27.8W 75 KT 85 MPH
12H 15/0600Z 36.4N 27.5W 75 KT 85 MPH
24H 15/1800Z 41.8N 27.9W 70 KT 80 MPH...POST-TROP/EXTRATROP
36H 16/0600Z 49.5N 29.7W 65 KT 75 MPH...POST-TROP/EXTRATROP
48H 16/1800Z 56.5N 34.0W 60 KT 70 MPH...POST-TROP/EXTRATROP
72H 17/1800Z...MERGED WITH ANOTHER EXTRATROPICAL CYCLONE