WTPA45 PHFO 310901
TCDCP5

HURRICANE MADELINE DISCUSSION NUMBER  20
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI   EP142016
1100 PM HST TUE AUG 30 2016
 
Latest satellite imagery shows that Madeline is weakening in the
presence of increasing shear, with conventional and microwave
imagery no longer detecting an eye. Hurricane hunters with the 53rd
Weather Reconnaissance Squadron spent a good portion of the evening
flying through the cyclone, and found that it was weaker than
anticipated, and tilted with height. The aircraft was also unable to
find an eye, with maximum flight level winds near 80 kt.
Satellite-based subjective Dvorak current intensity estimates were
5.0/90 kt, while data-T values ranged from 4.0/65 kt to 5.0/90 kt.
The initial intensity for this advisory has been lowered to 80 kt,
and this is likely generous based on the majority of the aircraft
data. 

The initial motion estimate for this advisory is 260/10 kt. 
The steering flow is being provided by a building mid-level ridge
to the north and northwest of the cyclone, which will impart a
motion just south of due west over the next 24 to 36 hours. After
this time, the ridge is expected to slide eastward, and a weakened
Madeline is expected to move toward the west-northwest in the low-
to mid-level trade wind flow. On the forecast track, the center of
Madeline will pass dangerously close to the Big Island (Hawaii
County) late Wednesday into Thursday, where a Hurricane Warning
remains in place. The updated track forecast is very close to the
previous as the bulk of the guidance suite continues to show
run-to-run consistency, and lies close to the TVCN multi-model
consensus. 

Madeline has rapidly weakened over the past 24 hours, and a steady
weakening trend dominates the forecast, even as Madeline moves over
warmer water. Vertical wind shear provided by a high-level trough to
the north and northwest of the cyclone is expected to cause steady
weakening as it imparts a debilitating northerly flow aloft and
severely hampers outflow. While the updated intensity forecast is
more aggressive in weakening Madeline than the previous forecast, it
lies on the higher end of the intensity guidance. If current trends
continue, then subsequent forecast packages may need to accelerate
the weakening trend, especially given that the latest ECMWF guidance
indicates dissipation by day 3 while the GFS and HWRF indicate
degeneration to a remnant low on days 4 and 5. 

 
FORECAST POSITIONS AND MAX WINDS
 
INIT  31/0900Z 19.2N 151.5W   80 KT  90 MPH
 12H  31/1800Z 19.0N 153.0W   75 KT  85 MPH
 24H  01/0600Z 18.7N 155.4W   70 KT  80 MPH
 36H  01/1800Z 18.5N 157.4W   60 KT  70 MPH
 48H  02/0600Z 18.6N 159.6W   55 KT  65 MPH
 72H  03/0600Z 18.8N 165.2W   50 KT  60 MPH
 96H  04/0600Z 19.2N 169.9W   45 KT  50 MPH
120H  05/0600Z 20.0N 174.0W   40 KT  45 MPH
 
$$
Forecaster Birchard