WTPA45 PHFO 301438
TCDCP5

HURRICANE MADELINE DISCUSSION NUMBER  16
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI   EP142016
500 AM HST TUE AUG 30 2016
 
Madeline's satellite presentation degraded overnight, with the eye
becoming cloud covered. The CDO has lost much of its symmetry, with
outflow becoming impaired to the south and west. Outflow remains
excellent to the north and northeast. Deep convection around the
LLCC remains robust, with cloud top temperatures colder than -70
degrees Celsius. Subjective Dvorak satellite intensity estimates
range from 5.5/102 kt from JTWC and SAB to 6.0/115 kt from PHFO,
while UW-CIMSS provided a noticeably lower ADT of 5.2/95 kt. We
will assign Madeline an initial intensity of 105 kt for this
advisory cycle, based on a rough average of the intensity
estimates. Hurricane hunters from the 53rd Weather Reconnaissance
Squadron are slated to begin flying investigative flights into
Madeline later this morning, which will give us valuable information
as to Madeline's actual intensity and size.

Initial motion is 280/09 kt. However, Madeline's westward track
component keeps increasing as six hour motion is closer to 270/09
kt. Madeline is tracking along the southern flank of the subtropical
ridge, but an upper trough northwest of the main Hawaiian Islands
allowed this system to gain latitude over the past few days. Global
models show this upper trough will lift northward through 48 hours,
giving the ridge a larger steering role by nudging Madeline westward
and west southwestward through day 2. Beyond 72 hours, the upper
trough is forecast to begin digging southward again, causing another
track bend to the west northwest on day 3 and beyond. Like before,
there are a few models that take Madeline over southern portions of
the Big Island, notably GFDL and ECMWF. However other models,
notably GFS, take Madeline noticeably farther south of the Big
Island. Small cosmetic changes were made to the forecast track at
48, 96 and 120 hours to keep it aligned with TVCN consensus, which
has handled this system superbly so far and lies firmly within the
guidance envelope.

Madeline reached peak intensity last evening but is now beginning
what is expected to be a gradual weakening trend through day 5. All
guidance shows weakening at various rates. The global models,
especially ECMWF, want to keep Madeline a hurricane through the
entire forecast period. In contrast, SHIPS reduces Madeline to a
tropical storm by 48 hours, due mainly to low SST potential and 20
kt of vertical shear depicted after 24 hours. Our forecast weakens
Madeline to a tropical storm after day 3 along a trend slightly
stronger than TCVN consensus. Most importantly, we keep this system
at hurricane strength as it passes just south of the Big Island of
Hawaii between 36 and 48 hours. 
 
Users are reminded to not focus too closely on the deterministic
forecast track, and that hazards associated with hurricanes can
extend well away from the center.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  30/1500Z 19.3N 148.3W  105 KT 120 MPH
 12H  31/0000Z 19.4N 149.7W   95 KT 110 MPH
 24H  31/1200Z 19.1N 151.7W   90 KT 105 MPH
 36H  01/0000Z 18.8N 153.7W   80 KT  90 MPH
 48H  01/1200Z 18.5N 155.7W   75 KT  85 MPH
 72H  02/1200Z 18.6N 159.9W   65 KT  75 MPH
 96H  03/1200Z 19.4N 164.4W   55 KT  65 MPH
120H  04/1200Z 20.2N 169.5W   50 KT  60 MPH
 
$$
Forecaster Powell