WTPA44 PHFO 130905 TCDCP4 TROPICAL STORM NORA DISCUSSION NUMBER 16 NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP182015 1100 PM HST MON OCT 12 2015 NORA IS STRUGGLING TO HOLD TOGETHER IN THE PRESENCE OF STRONG WEST- SOUTHWESTERLY SHEAR THIS EVENING...AS EVIDENT BY THE VERY LIMITED AMOUNT OF DEEP CONVECTION NEAR THE LOW LEVEL CIRCULATION CENTER /LLCC/. THE LATEST UW-CIMSS VERTICAL WIND SHEAR ANALYSIS INDICATES 25 KNOTS OF SHEAR FROM 245 DEGREES...WHILE SHIPS GUIDANCE SHOWS 32 KNOTS OF SHEAR FROM 260 DEGREES. THE LATEST FIXES FROM PHFO AND JTWC CAME IN AT 2.5/35 KNOTS...SAB 2.0/30 KNOTS...WHILE THE UW-CIMSS ADVANCED DVORAK TECHNIQUE /ADT/ CAME IN AT 2.5/35 KNOTS. FOR THE CURRENT ADVISORY...THE INTENSITY WILL BE LOWERED...PERHAPS CONSERVATIVELY TO 40 KNOTS BASED ON THE FIXES FROM THE AGENCIES AND THE EXPECTATION THAT CONVECTION WILL CONTINUE TO PERIODICALLY PULSE OVER THE LLCC THROUGH THE NIGHT. THE INITIAL MOTION WILL BE SET AT 295 DEGREES AT 9 KNOTS. NORA IS CURRENTLY BEING STEERED TO THE WEST-NORTHWEST ON THE SOUTHWESTERN PERIPHERY OF AN UPPER LEVEL RIDGE LOCATED NORTHEAST OF THE SYSTEM...AND THIS MOTION IS EXPECTED TO CONTINUE TONIGHT AND TUESDAY. A SHIFT TOWARD THE NORTH-NORTHWEST AND A DECREASE IN FORWARD SPEED IS EXPECTED TUESDAY NIGHT THROUGH WEDNESDAY NIGHT AS AN UPPER LEVEL TROUGH APPROACHES FROM THE WEST AND BEGINS TO INFLUENCE THE SYSTEM. WITH THE APPROACH OF THE UPPER LEVEL TROUGH...STRONG WEST-SOUTHWESTERLY SHEAR OF 30 TO 35 KNOTS AS INDICATED BY SHIPS GUIDANCE...WILL CONTINUE TO HAMMER NORA THROUGH WEDNESDAY NIGHT. THE PERSISTENT SHEAR WILL LIKELY RESULT IN A LOSS OF ALL DEEP CONVECTION NEAR THE LLCC BY WEDNESDAY EVENING...ALLOWING THE SYSTEM TO BE STEERED BY THE LOW LEVEL TRADE WIND FLOW AND OFF TO THE WEST PRIOR TO DISSIPATION. THE LATEST OFFICIAL FORECAST TRACK FROM CPHC CLOSELY FOLLOWS THE PREVIOUS OFFICIAL FORECAST THROUGH 24 HOURS. THE TRACK IS THEN SLIGHTLY NORTH OF THE PREVIOUS FORECAST TRACK DURING THE 24 TO 48 HOUR TIME FRAME...TAKING INTO ACCOUNT THE APPROACHING UPPER TROUGH WHICH WILL LIKELY ALLOW FOR A MORE NORTHWARD MOVEMENT OF THE SYSTEM. THE ADJUSTMENTS MADE TO THE FORECAST TRACK ARE CLOSELY IN LINE WITH THE LATEST GFEX...TVCN...AND FSSE THROUGH 48 HOURS...THEN CLOSER TO THE PREVIOUS OFFICIAL FORECAST TRACK THROUGH DISSIPATION. SLOW WEAKENING OF NORA IS EXPECTED DURING THE NEXT SEVERAL DAYS AS PERSISTENT VERTICAL WIND SHEAR CONTINUES TO INFLUENCE THE SYSTEM. ALTHOUGH THERE IS SIGNIFICANT SHEAR IN PLACE OVER NORA ALONG WITH PLENTY OF MID-LEVEL DRY AIR NOW GETTING WRAPPED UP INTO THE SYSTEM...THE COMBINATION OF WARM SEA SURFACE TEMPERATURES /SSTS/ OF 28 TO 29C AND INCREASING UPPER SUPPORT FROM AN APPROACHING UPPER LEVEL TROUGH...MAY BE ENOUGH TO ALLOW FOR PULSING DEEP CONVECTION NEAR THE LLCC THROUGH WEDNESDAY. AS A RESULT...THE INTENSITY FORECAST WILL KEEP NORA A MINIMAL TROPICAL STORM THROUGH TUESDAY...WITH THE SYSTEM BECOMING A TROPICAL DEPRESSION TUESDAY NIGHT. ONCE THE INFLUENCE OF THE UPPER LEVEL TROUGH IS LOST WEDNESDAY NIGHT...TROPICAL CHARACTERISTICS WILL STEADILY DIMINISH...WITH THE SYSTEM EXPECTED TO BE A POST TROPICAL REMNANT LOW BY FRIDAY EVENING AND DISSIPATED BY SATURDAY EVENING. FORECAST POSITIONS AND MAX WINDS INIT 13/0900Z 13.8N 148.5W 40 KT 45 MPH 12H 13/1800Z 14.4N 149.5W 35 KT 40 MPH 24H 14/0600Z 15.3N 150.5W 35 KT 40 MPH 36H 14/1800Z 16.0N 150.7W 30 KT 35 MPH 48H 15/0600Z 16.4N 151.1W 30 KT 35 MPH 72H 16/0600Z 16.5N 151.5W 25 KT 30 MPH 96H 17/0600Z 16.5N 153.0W 25 KT 30 MPH...POST-TROP/REMNT LOW 120H 18/0600Z...DISSIPATED $$ FORECASTER JELSEMA/HOUSTON