850 
 WTPA45 PHFO 190251
 TCDCP5
 
 TROPICAL DEPRESSION FIVE-C DISCUSSION NUMBER   1
 NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI   CP052015
 500 PM HST FRI SEP 18 2015
  
 THE TROPICAL DISTURBANCE CENTERED ABOUT 360 MILES WEST-NORTHWEST OF 
 JOHNSTON ISLAND DEVELOPED WELL-DEFINED BANDING WITHIN THE EASTERN 
 SEMICIRCLE AND NORTHERN QUADRANT TODAY. A 2102 UTC ASCAT PASS 
 DETECTED A CLOSED CIRCULATION AROUND AN ELONGATED CENTER WITH A 
 SURFACE TROUGH EXTENDING TO THE SOUTHWEST AND NUMEROUS AREAS OF 30 
 KT WINDS WITHIN THE NORTHERN SEMICIRCLE. THEREFORE...ADVISORIES ARE 
 BEING INITIATED ON TROPICAL DEPRESSION FIVE-C...THE TENTH TROPICAL 
 CYCLONE IN THE CENTRAL NORTH PACIFIC FOR THE 2015 SEASON. DVORAK 
 CURRENT INTENSITY ESTIMATES CAME IN AT 2.0/30 KT FROM HFO AND SAB 
 AND 1.5/25 KT FROM JTWC. THE INITIAL INTENSITY WILL BE SET AT 30 KT.
 
 THE INITIAL MOTION IS TOWARD THE NORTHEAST...OR 35 DEGREES...AT 13 
 KT. THE DEPRESSION IS MOVING ALONG THIS TRACK BETWEEN A DEEP RIDGE 
 FAR TO THE NORTHEAST AND A DIGGING MID TO UPPER LEVEL TROUGH 
 APPROACHING FROM THE NORTHWEST. ASIDE FROM A SLIGHT DECREASE IN 
 FORWARD MOTION...LITTLE CHANGE IN THE MOTION IS EXPECTED INTO 
 SATURDAY. THE CYCLONE WILL TURN TOWARD THE NORTH AND ACCELERATE ON 
 SUNDAY THROUGH TUESDAY AS IT INCREASINGLY INTERACTS WITH THE SLOW
 MOVING MID TO UPPER LEVEL TROUGH. THE TRACK FORECAST IS NEAR THE
 MIDDLE OF A RATHER TIGHTLY CLUSTERED DYNAMICAL AND CONSENSUS MODEL
 ENVELOPE THROUGH 72 HOURS AND IS ON THE LEFT SIDE OF DIVERGING
 GUIDANCE THEREAFTER.
 
 SLOW INTENSIFICATION IS EXPECTED IN THE SHORT TERM. THE CYCLONE
 WILL BE MOVING OVER VERY WARM SEA SURFACE TEMPERATURES...BUT THE
 BIG CHALLENGE IS HOW THE SYSTEM RESPONDS TO VERTICAL WIND SHEAR.
 FIVE-C IS CURRENTLY NORTH OF THE RIDGE AXIS ALOFT AND IS
 EXPERIENCING SOUTHWESTERLY UPPER LEVEL WINDS. THIS FLOW IS
 RESTRICTING OUTFLOW IN THE SOUTHWEST QUADRANT BUT IS PRODUCING AN
 OUTFLOW CHANNEL TO THE NORTH AND EAST. AS THE UPPER LEVEL TROUGH
 EDGES CLOSER...VERTICAL WIND SHEAR WILL RAMP UP QUICKLY AND ARREST
 THE INTENSIFICATION TREND. THE OFFICIAL FORECAST FOLLOWS LGEM
 CLOSELY AND ASSUMES THAT THIS PROCESS WILL BEGIN LATE SATURDAY OR
 SUNDAY. THIS FORECAST IS ON THE LOWER END OF THE GUIDANCE
 ENVELOPE...IN WHICH MOST MEMBERS ALLOW THE SYSTEM TO INTENSIFY
 SLIGHTLY LONGER.
 
 TROPICAL STORM WATCHES HAVE BEEN ISSUED FOR THE CENTRAL PORTIONS OF 
 THE PAPAHANAUMOKUAKEA NATIONAL MARINE MONUMENT FROM LISIANSKI
 ISLAND TO MARO REEF TO FRENCH FRIGATE SHOALS. IF CURRENT TRENDS
 CONTINUE...WARNINGS WILL LIKELY BE ISSUED TONIGHT OR SATURDAY. 
  
  
 FORECAST POSITIONS AND MAX WINDS
  
 INIT  19/0300Z 18.6N 174.5W   30 KT  35 MPH
  12H  19/1200Z 19.8N 173.5W   35 KT  40 MPH
  24H  20/0000Z 21.1N 172.9W   40 KT  45 MPH
  36H  20/1200Z 22.9N 172.6W   45 KT  50 MPH
  48H  21/0000Z 24.8N 172.3W   45 KT  50 MPH
  72H  22/0000Z 29.5N 172.2W   45 KT  50 MPH...POST-TROPICAL
  96H  23/0000Z 37.1N 172.9W   40 KT  45 MPH...POST-TROPICAL
 120H  24/0000Z 42.2N 176.8W   35 KT  40 MPH...POST-TROPICAL
  
 $$
 FORECASTER WROE