WTPA45 PHFO 211504

TCDCP5



TROPICAL STORM MALIA DISCUSSION NUMBER  12

NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI   CP052015

500 AM HST MON SEP 21 2015



THE LOW LEVEL CENTER OF CIRCULATION /LLCC/ OF FIVE-C MOVED CLOSER

TO THE DEEP CONVECTION EARLIER TONIGHT. ABOUT THE SAME TIME...GALE

FORCE WINDS BECAME EVIDENT IN AN 0827Z SCATTEROMETER PASS. ONCE THIS

BECAME EVIDENT...A SPECIAL ADVISORY WAS ISSUED AT 1200Z TO UPGRADE

TROPICAL DEPRESSION FIVE-C TO TROPICAL STORM MALIA...PRONOUNCED

MAH-LEE-AH. ADDITIONAL CONFIRMATION FOR THIS CHANGE IN STATUS OF

THE SYSTEM WERE THE LATEST SUBJECTIVE DVORAK CURRENT INTENSITY

ESTIMATES...2.5/35 KT FROM JTWC AND HFO...AND 2.0/30 KT FROM SAB.

THE 1200Z UW-CIMSS ADT ESTIMATE WAS 2.2/32 KT. THEREFORE...THE

INITIAL INTENSITY WILL REMAIN 35 KT FOR THIS ADVISORY.



THE INITIAL MOTION OF MALIA IS TOWARD THE NORTH-NORTHEAST OR 025

DEGREES AT 10 KT. THE PRIMARY STEERING MECHANISMS FOR THIS

SYSTEM ARE A DEEP LAYER TROUGH FAR TO THE WEST NEAR LONGITUDE

173E...AND A DEEP LAYER RIDGE LOCATED FAR TO THE EAST AND NORTHEAST.

THE SYSTEM IS EXPECTED TO CONTINUE ON THIS TRACK THROUGH THIS

MORNING WITH A GRADUAL TURN TOWARD THE NORTH LATER TODAY AND

TONIGHT. MALIA IS THEN FORECAST TO MOVE TOWARD THE NORTH-NORTHWEST

AT A FASTER FORWARD SPEED DURING THE 24 TO 36 HOUR TIME PERIOD AS

THE SYSTEM BECOMES ENTANGLED WITH THE CIRCULATION OF THE DEEP LAYER

TROUGH. MOST OF THE RELIABLE DYNAMICAL TRACK GUIDANCE REMAINS

REASONABLY WELL CLUSTERED DURING THE NEXT 36 HOURS...WITH INCREASING

SPREAD FROM DAYS 2 THROUGH 5. THE LATEST OFFICIAL TRACK IS VERY

CLOSE TO THE PREVIOUS THROUGH 24 HOURS. AFTER THAT...THE 36 HOUR

POSITION WAS ACCELERATED AND SHIFTED TO THE LEFT. THIS WAS DONE TO

BLEND WITH THE 48...72 AND 96 HOUR POSITIONS THAT WERE COORDINATED

WITH THE OCEAN PREDICTION CENTER /OPC/.



THE LATEST ESTIMATES OF ENVIRONMENTAL VERTICAL WIND SHEAR IN THE

VICINITY OF FIVE-C WERE WELL IN EXCESS OF 30 KT FROM THE

WEST-SOUTHWEST ACCORDING TO THE UW-CIMSS AND SHIPS GUIDANCE. THIS

INCREASING SHEAR COMBINED WITH GRADUAL COOLING OF THE OCEAN WATER

TEMPERATURES AND HEAT CONTENT UNDER THE FUTURE TRACK OF MALIA ARE

LIKELY DETRIMENTAL TO THE LONG TERM HEALTH OF THE SYSTEM AS A WARM

CORE TROPICAL SYSTEM. HOWEVER...THE INCREASING SHEAR HAS LIKELY

PRODUCED DIFFLUENCE ALOFT ACROSS THE SYSTEM...WHICH HAS CONTINUED TO

ALLOW THUNDERSTORMS TO DEVELOP IN A LARGE CLUSTER NORTHEAST OF THE

CENTER. AT THE SAME TIME...THE TIGHTENING OF THE PRESSURE GRADIENT

BETWEEN MALIA AND THE SUBTROPICAL RIDGE LOCATED MORE THAN 500

NM TO THE NORTH SHOULD CAUSE SURFACE WINDS TO STEADILY INCREASE...

ESPECIALLY IN THE NORTH AND NORTHEAST QUADRANTS. AS A RESULT...THE

SYSTEM WILL LIKELY REMAIN A TROPICAL STORM EVEN IF CONVECTION

BEGINS TO WEAKEN LATER TODAY OR TONIGHT. MALIA WILL EVENTUALLY BEGIN

TO UNDERGO AN EXTRATROPICAL TRANSITION...WITH THE CURRENT FORECAST

NOW SHOWING THIS WILL HAPPEN BEYOND 36 HOURS. THE LATEST OPC INPUT

INDICATES THIS EXTRATROPICAL TRANSITION WILL OCCUR BETWEEN 36 AND 48

HOURS. THE 48...72 AND 96 HOUR INTENSITY...AS WELL AS THE 48 AND 72

HOUR 34 KT WIND RADII FORECASTS WERE ALSO COORDINATED WITH OPC.



A TROPICAL STORM WARNING REMAINS POSTED FOR PORTIONS OF THE

PAPAHANAUMOKUAKEA MARINE NATIONAL MONUMENT FROM FRENCH FRIGATE

SHOALS TO MARO REEF TO LISIANSKI ISLAND. TROPICAL STORM CONDITIONS

WILL CONTINUE OVER MANY OF THESE VULNERABLE LOW LYING ISLANDS AND

ATOLLS INTO TONIGHT.





FORECAST POSITIONS AND MAX WINDS



INIT  21/1500Z 25.1N 171.0W   35 KT  40 MPH

 12H  22/0000Z 26.6N 171.4W   40 KT  45 MPH

 24H  22/1200Z 29.0N 172.2W   40 KT  45 MPH

 36H  23/0000Z 33.0N 174.5W   45 KT  50 MPH

 48H  23/1200Z 38.4N 176.5E   45 KT  50 MPH...POST-TROP/EXTRATROP

 72H  24/1200Z 43.9N 173.3E   40 KT  45 MPH...POST-TROP/EXTRATROP

 96H  25/1200Z 50.4N 169.9E   35 KT  40 MPH...POST-TROP/EXTRATROP

120H  26/1200Z...DISSIPATED



$$

FORECASTER HOUSTON