WTPA45 PHFO 290840
TCDCP5

HURRICANE MADELINE DISCUSSION NUMBER  11
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI   EP142016
1100 PM HST SUN AUG 28 2016
 
Madeleine has become more organized over the past 12 hours, with an
eye feature forming within the central dense overcast and becoming
apparent this evening. Little or no shear deformation is noted and
outflow is particularly good to the north. Subjective Dvorak
satellite intensity estimates are 4.5, 77 kt, from all three
satellite analysis centers. Given the greatly improved
organization, eye feature and unanimous intensity estimates,
Madeline is upgraded to a hurricane and assigned an initial
intensity of 75 kt for this advisory cycle.
 
An upper trough northwest of the main Hawaiian Islands continues to
allow Madeline to gain latitude as this system tracks along the
southern flank of the subtropical ridge. Global models show this
upper trough will lift northward through 72 hours, allowing the
ridge to steer Madeline along a more westerly track beyond 12
hours. Interestingly, the upper trough is then forecast to begin
digging southward again by 72 hours a bit farther to the east,
causing some of the track guidance to deflect Madeline to the west
northwest again near 120 hours, after this system has passed the
Hawaiian Islands. Track guidance is reassuringly tightly packed
through 72 hours with even GFDL, which had been the right outlier
for the guidance we most commonly use, now taking Madeline south of
the Big Island. There is little change in the forecast track, which
lies south of GFDL but just north of most of the consensus guidance.

SHIPS probability for rapid intensification is over 30 percent
through 24 hours. This aligns with most intensity guidance showing
Madeline reaching peak intensity by day 2, then suffering a gradual
decline as SSTs drop and shear begins to increase. Our intensity
forecast tops Madeline out at 85 kt at 24 hours, followed by a
decline through day 5. While depicted as stronger than last time at
all tau beyond day 2, the rate of weakening beyond day 2 was
actually increased with this package to keep pace with SHIPS and
IVCN consensus.

As usual, the confidence in the track forecast decreases by day 3,
so it is difficult to determine what impacts Madeline could have on
the Hawaiian Islands late in the forecast period.  It is important
to remember that the average day 4 and 5 track forecast errors for
central Pacific tropical cyclones is around 185 and 250 miles,
respectively.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  29/0900Z 17.8N 143.7W   75 KT  85 MPH
 12H  29/1800Z 18.4N 145.1W   80 KT  90 MPH
 24H  30/0600Z 18.9N 146.8W   85 KT 100 MPH
 36H  30/1800Z 19.1N 148.6W   80 KT  90 MPH
 48H  31/0600Z 19.0N 150.6W   75 KT  85 MPH
 72H  01/0600Z 18.5N 154.8W   70 KT  80 MPH
 96H  02/0600Z 17.6N 159.0W   60 KT  70 MPH
120H  03/0600Z 16.7N 163.3W   55 KT  65 MPH
 
$$
Forecaster Powell