WTPA45 PHFO 010248
TCDCP5

TROPICAL STORM MADELINE DISCUSSION NUMBER  23
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI   EP142016
500 PM HST WED AUG 31 2016
 
The satellite presentation of Madeline continues to degrade. The
low level center remains partially exposed in the southwestern
semicircle, and deep convection is confined to the northeast
quadrant. Dvorak current intensity estimates range from 45 kt out of
SAB, 55 from HFO, and 65 kt from JTWC.  A U.S. Air Force
Reconnaissance aircraft had difficulty locating the center and
reported a maximum surface wind of 44 kt in the northwest quadrant.
However, the aircraft may not have sampled the strongest winds in
the northeast quadrant. Given the aircraft data and a blend of the
Dvorak estimates, the initial intensity is lowered to 55 kt for this
advisory.
 
The initial motion for this advisory is 250/11 kt. Madeline is being
steered west-southwestward by a strong low to mid level ridge to the
northwest and north of Hawaii. Along this track, Madeline will pass
just south of the Big Island of Hawaii (Hawaii County) tonight. On
Thursday, the cyclone is expected to resume a westerly track, away
from the main Hawaiian Islands, and continue moving generally
westward through Monday. The forecast track has been changed little
from the prior advisory and continues to run along the northern
portion of a rather tightly clustered dynamical model guidance
envelope. There are some along track differences in the guidance,
with the ECMWF being notably faster with the forward motion of
Madeline.
 
Madeline will continue to weaken during the next two days under the
influence of vertical wind shear produced by an upper level trough
dropping over Hawaii. The official intensity forecast follows SHIPS
and IVCN closely through 48 hours. Beyond that time the guidance
diverges due to a weakening of the vertical wind shear, with SHIPS
and IVCN holding Madeline at tropical storm intensity through day
five and HWRF steadily weakening the cyclone. The official forecast
assumes that the vertical wind shear will be strong enough to weaken
Madeline to a tropical depression on Saturday and that
re-intensification will be unlikely, as Madeline will remain near
the upper level trough axis.
 
With Madeline passing just south of the Big Island tonight, a
Tropical Storm Warning remains posted for the Big island, where
numerous observing sites have been reporting tropical storm force
gusts today. Maui County also remains under a Tropical Storm
Warning, as winds will be accelerated over and around mountainous
terrain tonight.
 
 
 
 
 
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  01/0300Z 18.0N 155.1W   55 KT  65 MPH
 12H  01/1200Z 17.7N 156.7W   45 KT  50 MPH
 24H  02/0000Z 17.5N 159.1W   40 KT  45 MPH
 36H  02/1200Z 17.4N 161.8W   35 KT  40 MPH
 48H  03/0000Z 17.4N 164.8W   30 KT  35 MPH
 72H  04/0000Z 17.4N 169.4W   30 KT  35 MPH
 96H  05/0000Z 17.6N 174.1W   30 KT  35 MPH...POST-TROP/REMNT LOW
120H  06/0000Z 18.1N 177.5W   30 KT  35 MPH...POST-TROP/REMNT LOW
 
$$
Forecaster Wroe