WTPA43 PHFO 240307 CCA

TCDCP3



TROPICAL STORM DARBY DISCUSSION NUMBER  50

NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI   EP052016

500 PM HST SAT JUL 23 2016



The 53rd Weather Reconnaissance Squadron flew through Darby for a

good portion of the day, and departed the storm just before the

poorly-defined center came ashore over the southeastern portion of

the Big Island near Pahala around 2 pm.  The center is estimated to

be traversing the southern slopes of the Big Island at this time.

Surface pressures were rising each time the plane sampled the

system, and flight-level winds indicated that Darby's intensity

had weakened to near 35 kt, and that is the initial intensity for

this advisory.  Another reconnaissance flight is scheduled for early

Sunday morning to determine what remains of Darby's circulation

after it emerges from the Big Island.



The initial motion is estimated to be 275/09 kt, with the

poorly-defined center of Darby currently estimated to be over

interior portions of the Big Island.  After emerging from the Big

Island later this evening, a turn toward the northwest is expected,

with Darby moving toward the northwest through the remainder of the

forecast period.  Darby is still expected to move into a weakness in

the mid-level ridge to its north over the next 24 hours, as a deep-

layer low remains nearly stationary far north of the Hawaiian

Islands.  While the spread in the track guidance has increased

slightly from the previous cycle, it continues to indicate a steady

northwest motion.  The updated track forecast is close to the

previous and the multi-model consensus TVCN.



As the center of Darby is currently over the Big Island, there is

considerable uncertainty as to what will remain of the low-level

circulation once it moves back over water later this evening.  The

intensity forecast is conservatively maintaining Darby as a minimal

tropical storm through 24 hours until it is clear that re-

development will not occur.  Thereafter, steady weakening is

anticipated, as increasing shear and gradually cooling waters lie

along the forecast track.  The updated forecast indicates weakening

to a remnant low in 72 hours, with dissipation expected by the end

of the forecast period.  This is a slower rate of weakening than

depicted by global models through the first 24 hours, and the

intensity consensus, IVCN, but closely follows IVCN thereafter. If

Darby's circulation does not survive its interaction with the Big

Island's rugged terrain, than dissipation will likely occur much

sooner.





FORECAST POSITIONS AND MAX WINDS



INIT  24/0300Z 19.3N 155.8W   35 KT  40 MPH...INLAND

 12H  24/1200Z 20.0N 156.9W   35 KT  40 MPH

 24H  25/0000Z 21.0N 158.4W   35 KT  40 MPH

 36H  25/1200Z 22.2N 159.8W   30 KT  35 MPH

 48H  26/0000Z 23.6N 161.3W   30 KT  35 MPH

 72H  27/0000Z 27.0N 164.7W   25 KT  30 MPH...POST-TROP/REMNT LOW

 96H  28/0000Z 30.8N 167.8W   20 KT  25 MPH...POST-TROP/REMNT LOW

120H  29/0000Z...DISSIPATED



$$

Forecaster Birchard