WTPA45 PHFO 181508 TCDCP5 HURRICANE ANA DISCUSSION NUMBER 20 NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI CP022014 500 AM HST SAT OCT 18 2014 LATEST SATELLITE IMAGERY SHOWS SEVERELY RESTRICTED OUTFLOW IN ANA/S WESTERN SEMICIRCLE...WITH 20 TO 25 KT OF SOUTHWESTERLY SHEAR NOTED IN RECENT UW-CIMSS ANALYSES. HOWEVER...DATA FROM A U.S. AIR FORCE RECONNAISSANCE AIRCRAFT INDICATE THAT ANA HAS NOT WEAKENED SIGNIFICANTLY SINCE THE PREVIOUS ADVISORY...WITH MAXIMUM SFMR WINDS NEAR 67 KT...AND MAXIMUM FLIGHT LEVEL WINDS OF 75 KT. A BLEND OF THE AVAILABLE DATA SUPPORTS LOWERING THE INITIAL INTENSITY TO 70 KT FOR THIS ADVISORY. INITIAL MOTION FOR THIS ADVISORY IS SET AT 315/11 KT...WITH ANA LOCATED ON THE SOUTHWEST PERIPHERY OF A LOW TO MID-LEVEL ANTICYCLONE. A WEAK RIDGE EXTENDS WESTWARD FROM THIS ANTICYCLONE... AND TO THE NORTH OF ANA...AND WILL HELP MAINTAIN THE CURRENT MOTION THROUGH MOST OF TODAY. A NEW RIDGE BUILDING EASTWARD FROM THE DATE LINE TONIGHT AND SUNDAY WILL RESULT IN A SLIGHT DECREASE IN FORWARD SPEED...AND A TURN TOWARD THE WEST. ALTHOUGH ANA HAS BEEN TRACKING SLIGHTLY TO THE RIGHT OF THE SHORT TERM FORECAST TRACK...THE UPDATED TRACK FORECAST IS LEFT OF THE PREVIOUS AT 24 AND 36 HOURS. THIS IS IN LINE WITH THE GUIDANCE SUITE...BUT THE OFFICIAL FORECAST CONTINUES TO RIDE THE RIGHT HAND SIDE OF THE GUIDANCE IN THE SHORT TERM. WHILE THE GUIDANCE...AND THE FORECAST...REMAINS STEADFAST IN A TURN TOWARD THE WEST BY TONIGHT...IF THE TURN OCCURS LATER OR IS NOT AS SHARP AS ANTICIPATED...WINDS ON THE PERIPHERY OF ANA COULD IMPACT OAHU OR KAUAI COUNTY...THUS A TROPICAL STORM WATCH REMAINS IN EFFECT. CONFIDENCE HAS INCREASED THAT MAUI COUNTY WILL NOT ENCOUNTER ANA/S WIND FIELD...AND THE TROPICAL STORM WATCH HAS BEEN CANCELLED. THE GENERAL MOTION TOWARD THE WEST WILL PERSIST ON MONDAY...BUT AS THE NEW RIDGE SLIDES EAST OF THE CYCLONE ON TUESDAY AND WEDNESDAY... ANA IS FORECAST TO MOVE ON AN INCREASINGLY NORTHWARD TRACK. BY DAYS 4 AND 5...ANA IS FORECAST TO BE NEAR THE PAPAHANAUMOKUAKEA MARINE NATIONAL MONUMENT...WITH TRACK GUIDANCE SHOWING INCREASING SPREAD AT THAT TIME. ANA IS FORECAST TO MAINTAIN ITS CURRENT INTENSITY OVER THE NEXT 12 HOURS...WITH MODEST WEAKENING THEN EXPECTED THROUGH DAY 3. PERSISTENT WESTERLY SHEAR IS EXPECTED TO PREVENT ANA FROM INTENSIFYING OVER THE ANOMALOUSLY WARM WATER LOCATED TO THE WEST AND NORTHWEST OF THE MAIN HAWAIIAN ISLANDS...UNTIL THE SHEAR BEGINS TO RELAX ON DAYS 4 AND 5. INTENSITY GUIDANCE IS OFFERING A WIDE RANGE OF SOLUTIONS AT THIS TIME...WITH THE LATEST FORECAST CLOSELY FOLLOWING THE TRENDS PRESENTED BY SHIPS AND LGEM GUIDANCE...WHICH INDICATE SOME RE-STRENGTHENING. THE IVCN CONSENSUS CONTINUES TO BE MUCH HIGHER THAN THE OFFICIAL FORECAST IN THE LONGER RANGES...AS HWRF AND GFDL STRENGTHEN ANA TO A STRONG HURRICANE. FORECAST POSITIONS AND MAX WINDS INIT 18/1500Z 18.5N 158.1W 70 KT 80 MPH 12H 19/0000Z 19.4N 159.3W 70 KT 80 MPH 24H 19/1200Z 19.9N 160.7W 65 KT 75 MPH 36H 20/0000Z 20.3N 162.2W 60 KT 70 MPH 48H 20/1200Z 20.6N 163.8W 60 KT 70 MPH 72H 21/1200Z 22.0N 166.3W 60 KT 70 MPH 96H 22/1200Z 24.0N 168.0W 65 KT 75 MPH 120H 23/1200Z 26.5N 168.5W 70 KT 80 MPH $$ FORECASTER BIRCHARD PALMBAYWEATHER.info
Posted on: Sat, 18 Oct 2014 15:08:56 +0000
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