WTPA44 PHFO 161456 TCDCP4 TROPICAL STORM PEWA DISCUSSION NUMBER 1 NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI CP012013 500 AM HST FRI AUG 16 2013 A BALL OF DEEP CONVECTION DEVELOPED OVER THE CENTER OF THE LOW PRESSURE SYSTEM FAR SOUTHWEST OF HAWAII YESTERDAY EVENING...AND HAS PERSISTED LONG ENOUGH TO WARRANT CLASSIFYING THE SYSTEM AS A TROPICAL CYCLONE. DVORAK CURRENT INTENSITY ESTIMATES ARE 2.5/35 KT FROM PHFO AND PGTW AND 2.0/30 KT FROM SAB. GIVEN THE PERSISTENT IMPRESSIVE SATELLITE APPEARANCE...THE INITIAL INTENSITY IS SET TO 35 KT...AND ADVISORIES ARE BEING INITIATED ON THE FIRST TROPICAL CYCLONE TO DEVELOP WITHIN THE CENTRAL NORTH PACIFIC BASIN IN THE 2013 SEASON...TROPICAL STORM PEWA. INITIAL MOTION ESTIMATE IS 290/11 KT...WITH THE STORM LOCATED ALONG THE SOUTHWESTERN EDGE OF A DEEP LAYER RIDGE. THE RIDGE IS FORECAST TO CHANGE MINIMALLY OVER THE NEXT COUPLE OF DAYS...KEEPING THE DEPRESSION MOVING ON A TRAJECTORY TOWARD THE WEST-NORTHWEST. THE OFFICIAL TRACK FORECAST IS CLOSE TO THE MULTI-MODEL CONSENSUS TVCE...AND LIES NEAR THE MIDDLE OF THE GUIDANCE ENVELOPE...WITH TRACK GUIDANCE SHOWING INCREASING SPREAD BEYOND DAY 3. THE STORM IS CURRENTLY IN AN ENVIRONMENT THAT IS CONDUCIVE FOR STRENGTHENING...CHARACTERIZED BY LIGHT WIND SHEAR AND WARM SSTS... WITH PEWA/S IMPRESSIVE OUTFLOW ALOFT SUPPRESSING THE DEVELOPMENT OF A DISTURBANCE ABOUT 550 MILES TO THE EAST-NORTHEAST. WATER TEMPERATURES AND OCEAN HEAT CONTENT ALONG THE FORECAST TRACK WILL REMAIN SUFFICIENTLY HIGH TO SUPPORT A STRONG SYSTEM...WITH THE ONLY LIMITING FACTOR BEING AN EXPECTED INCREASE IN SOUTHWESTERLY SHEAR IN DAYS 3 THROUGH 5...AS THE STORM ROUNDS THE WESTERN EDGE OF THE RIDGE. THEREFORE...A STEADY INTENSIFICATION TREND IS INDICATED IN THE SHORT TERM...WITH A SLOW WEAKENING TREND COMMENCING BY DAY 3... WHICH IS LINE WITH THE MAJORITY OF THE INTENSITY GUIDANCE. FORECAST POSITIONS AND MAX WINDS INIT 16/1500Z 10.2N 173.5W 35 KT 40 MPH 12H 17/0000Z 10.8N 175.1W 40 KT 45 MPH 24H 17/1200Z 11.4N 177.2W 45 KT 50 MPH 36H 18/0000Z 12.2N 179.6W 50 KT 60 MPH 48H 18/1200Z 13.0N 177.8E 50 KT 60 MPH 72H 19/1200Z 15.0N 172.5E 45 KT 50 MPH 96H 20/1200Z 17.0N 167.0E 40 KT 45 MPH 120H 21/1200Z 19.0N 162.0E 35 KT 40 MPH $$ FORECASTER BIRCHARD For more information, go to middletnweather.info
Posted on: Fri, 16 Aug 2013 14:58:09 +0000
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