WTPA41 PHFO 312048 TCDCP1 TROPICAL DEPRESSION NINE-C DISCUSSION NUMBER 4 NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI CP092015 1100 AM HST THU DEC 31 2015 TROPICAL DEPRESSION NINE-C REMAINS RATHER UNORGANIZED THIS MORNING WITH THE LOW LEVEL CIRCULATION CENTER DIFFICULT TO LOCATE. THE FIX POSITIONS FROM PHFO...SAB AND JTWC WERE UP TO 120 MILES APART SO CONFIDENCE IN THE INITIAL FIX POSITION IS RATHER LOW. THE INITIAL POSITION FOR THIS PACKAGE IS CLOSE TO PHFO WHICH LIES IN THE MIDDLE OF THE SAB AND JTWC FIX POSITIONS. THE MOST RECENT SUBJECTIVE DVORAK SATELLITE CURRENT INTENSITY ESTIMATES ARE 2.0/30 KT FROM ALL THREE FIX AGENCIES. BASED ON THESE INTENSITY ESTIMATES AS WELL AS ITS CURRENT APPEARANCE ON SATELLITE IMAGERY...WE WILL KEEP THE SYSTEM AT 30 KT WITH THIS ADVISORY. THE INTENSITY FORECAST REMAINS PROBLEMATIC WITH A WIDE RANGE GIVEN FROM MODEL GUIDANCE. THE SYSTEM REMAINS IN A SHEARED ENVIRONMENT WITH BOTH SHIPS AND UW-CIMSS INDICATING SHEAR VALUES OF AROUND 20 KT OVER THE SYSTEM. SHIPS INDICATES LITTLE CHANGE IN SHEAR VALUES OVER THE NEXT FEW DAYS WITH A BIT LESS SHEAR INDICATED BEYOND DAY 3. THE SYSTEM WILL REMAIN OVER WARM WATER THROUGHOUT THE FORECAST PERIOD. SHIPS AND IVCN GUIDANCE SLOWLY STRENGTHEN NINE-C TO A HURRICANE BY AROUND DAY 4. THERE IS ALSO THE POSSIBILITY THAT THE SYSTEM COULD DISSIPATE WITHIN A FEW DAYS AS INDICATED BY HWFI AND GFDI. THE GFS MODEL KEEPS THE SYSTEM PRETTY MUCH IN A STEADY STATE THROUGH DAY 5 WHILE THE ECMWF WEAKENS THE SYSTEM RAPIDLY OVER THE NEXT COUPLE OF DAYS. THE LATEST FORECAST REMAINS UNCHANGED FROM THE PREVIOUS FORECAST KEEPING THE SYSTEM A DEPRESSION OVER THE NEXT FEW DAYS WITH SOME SLOW STRENGTHENING TO A TROPICAL STORM ON DAYS 4 AND 5. THE INITIAL MOTION ESTIMATE FOR THIS ADVISORY IS 315/03 KT. AS WITH THE PREVIOUS ADVISORY...FORECAST TRACK GUIDANCE FOR NINE-C REMAINS UNRELIABLE. THERE REMAINS A WIDE SPREAD IN TRACK GUIDANCE ESPECIALLY DUE TO MODEL DIFFERENCES WITH INTENSITY GUIDANCE. THE LATEST TRACK FORECAST FOLLOWS CLOSELY WITH THE PREVIOUS FORECAST WITH A SLOW WEST NORTHWEST MOTION EXPECTED THROUGH DAY 5. FORECAST POSITIONS AND MAX WINDS INIT 31/2100Z 2.7N 177.5W 30 KT 35 MPH 12H 01/0600Z 2.8N 177.9W 30 KT 35 MPH 24H 01/1800Z 2.9N 178.2W 30 KT 35 MPH 36H 02/0600Z 3.1N 178.6W 30 KT 35 MPH 48H 02/1800Z 3.4N 179.1W 30 KT 35 MPH 72H 03/1800Z 3.9N 179.9E 30 KT 35 MPH 96H 04/1800Z 4.5N 178.4E 35 KT 40 MPH 120H 05/1800Z 5.0N 177.0E 40 KT 45 MPH $$ FORECASTER BURKE WTPA41 PHFO 311438 TROPICAL DEPRESSION NINE-C DISCUSSION NUMBER 3 NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI CP092015 500 AM HST THU DEC 31 2015 TROPICAL DEPRESSION NINE-C...THE SIXTEENTH TROPICAL CYCLONE OF 2015 IN THE NORTH CENTRAL PACIFIC BASIN...CONTINUES TO PROVIDE MANY CHALLENGES EARLY THIS MORNING. THE PRIMARY PROBLEM REMAINS THE LOCATION OF THE LOW-LEVEL CIRCULATION CENTER /LLCC/ OF THE DEPRESSION. NIGHTTIME INFRARED SATELLITE IMAGERY FROM THE HIMAWARI SATELLITE HAS BEEN USEFUL IN MONITORING THE SHORT-TERM CHANGES IN THE EXTENSIVE CONVECTIVE CLOUD TOPS NEAR THE APPARENT LLCC. HOWEVER...EVEN WITH 10-MINUTE INTERVAL HIGH-RESOLUTION SATELLITE IMAGERY...THE CIRRUS CANOPY OVER THE SYSTEM CONTINUES TO OBSCURE MOST OF THE LOWER-LEVEL CUMULUS AND TOWERING CUMULUS CLOUDS THAT MIGHT HELP US TO LOCATE THE LLCC. ONCE AGAIN...ALL OF THE SATELLITE FIX AGENCIES...PHFO...SAB AND JTWC...PROVIDED POSITION FIXES THAT ARE IN RELATIVELY CLOSE PROXIMITY. THE MOST RECENT SUBJECTIVE DVORAK SATELLITE CURRENT INTENSITY ESTIMATES ARE 2.0/30 KT FROM JTWC AND SAB...WHILE THE PHFO VALUE IS 2.5/35 KT. THE LATEST CIMSS ADT ESTIMATE IS 2.9/43 KT. THE ENVIRONMENTAL VERTICAL WIND SHEAR IN THE VICINITY OF NINE-C ACCORDING TO SHIPS IS 23 KT FROM 110 DEGREES. DUE TO THE UNCERTAINTY IN THE EXACT LOCATION OF THE LLCC IN A HIGHLY SHEARED ENVIRONMENT...WE WILL MAINTAIN THE INITIAL INTENSITY ESTIMATE AT 30 KT FOR THIS ADVISORY. THE INITIAL MOTION ESTIMATE FOR THIS ADVISORY IS AN UNCERTAIN 300/02 KT. AS WITH THE PREVIOUS ADVISORY...FORECAST TRACK GUIDANCE FOR NINE-C REMAINS UNRELIABLE...IF IT IS AVAILABLE. SINCE THE GFDL AND HWRF GUIDANCE MOVE NINE-C IN COMPLETELY OPPOSITE DIRECTIONS AND THERE IS NO ECMWF FORECAST AVAILABLE...THE CONSENSUS MODELS WE NORMALLY RELY ON ARE AMBIGUOUS. NOTE ALSO THAT GFDL AND HWRF DISSIPATE NINE-C IN 2 TO 3 DAYS. THE GFS ENSEMBLE MEAN FORECAST IS AVAILABLE...SO WE USED THAT TO MODIFY THE PREVIOUS OFFICIAL FORECAST TRACK. THE LATEST FORECAST TRACK REMAINS CLOSE TO THE PREVIOUS...BUT THE FORWARD MOTION OF THE SYSTEM HAS BEEN DECREASED. NEAR EQUATORIAL SEA SURFACE TEMPERATURES OF NEAR 30 DEGREES C...AS WELL AS HIGH VALUES OF OCEAN HEAT CONTENT AS DEPICTED ON THE CIRA WEB SITE...APPEAR TO BE MAJOR FACTORS THAT MIGHT ULTIMATELY KEEP NINE-C ALIVE. HOWEVER...THE LATEST FORECAST AGAIN INDICATES THE SYSTEM WILL DEVELOP SLOWLY...IF AT ALL...DUE TO THE STRONG EASTERLY SHEAR IN THE 20 TO 25 KT RANGE ACCORDING TO THE LATEST SHIPS GUIDANCE. IF NINE-C AVOIDS DISSIPATION...IT IS FORECAST TO REACH TROPICAL STORM INTENSITY BY DAY 4 AS IT APPROACHES THE INTERNATIONAL DATE LINE. NOTE ALSO THAT THIS FORECAST CONTINUES TO DELAY THE POTENTIAL CROSSING OF NINE-C INTO THE NORTHWEST PACIFIC UNTIL AROUND DAY 5. FORECAST POSITIONS AND MAX WINDS INIT 31/1500Z 2.4N 176.1W 30 KT 35 MPH 12H 01/0000Z 2.5N 176.2W 30 KT 35 MPH 24H 01/1200Z 2.7N 176.6W 30 KT 35 MPH 36H 02/0000Z 2.9N 177.0W 30 KT 35 MPH 48H 02/1200Z 3.1N 177.4W 30 KT 35 MPH 72H 03/1200Z 3.5N 178.2W 30 KT 35 MPH 96H 04/1200Z 3.9N 179.0W 35 KT 40 MPH 120H 05/1200Z 4.3N 180.0E 40 KT 45 MPH $$ FORECASTER HOUSTON WTPA41 PHFO 310859 TROPICAL DEPRESSION NINE-C DISCUSSION NUMBER 2 NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI CP092015 1100 PM HST WED DEC 30 2015 AS WE APPROACH THE BEGINNING OF THE NEW YEAR AND WELL AFTER THE END OF THE OFFICIAL NORTH CENTRAL PACIFIC HURRICANE SEASON...NEWLY FORMED TROPICAL DEPRESSION IS PROVIDING MANY CHALLENGES THIS EVENING. AS WITH MOST DEVELOPING SYSTEMS...WE CAN EXPECT DIFFICULTIES IN LOCATING THE LOW-LEVEL CIRCULATION CENTER /LLCC/. ADD THE CLOSE PROXIMITY OF A TROPICAL CYCLONE TO THE EQUATOR AND THIS MAKES THE USUAL CENTER FINDING TECHNIQUES LESS RELIABLE. THE CONVECTIVE STRUCTURE OF NINE-C CONTINUES TO SUGGEST AN ELONGATED EAST TO WEST ORIENTED SYSTEM...WHICH INDICATES THERE LIKELY IS STILL A LOW-LEVEL TROUGH-LIKE FEATURE ASSOCIATED WITH THE NINE-C. THIS IS NOT UNEXPECTED WHEN EXAMINING THE UNUSUAL BELT OF STRONG WESTERLY WINDS SOUTH OF THE EQUATOR...AS WELL AS THE EXTENSIVE AREA OF 30 KT EASTERLY WINDS TO THE NORTH OF NINE-C. ANIMATED HIMAWARI VISIBLE / INFRARED SATELLITE IMAGERY AND A 0211 UTC AMSU PASS WERE OF SOME ASSISTANCE IN FINDING THE APPARENT CENTER. OF MORE IMPORTANCE...ALL OF THE FIX AGENCIES...PHFO...SAB AND JTWC...PROVIDED POSITION FIXES THAT WERE VERY CLOSE TO THE SAME AREA. IN ADDITION...ALL THREE AGENCIES INDICATED THE LATEST SUBJECTIVE DVORAK SATELLITE INTENSITY ESTIMATE IS 2.0 OR 30 KT. THIS SEEMS REASONABLE BASED ON THE APPARENT LOCATION OF THE LLCC. THE DEEP CONVECTION IS DISPLACED JUST TO THE WEST OF THE LLCC DUE TO STRONG ENVIRONMENTAL VERTICAL WIND SHEAR. THE LATEST ESTIMATE OF WIND SHEAR FROM SHIPS IS 31 KT FROM 130 DEGREES. WE WILL MAINTAIN THE INITIAL INTENSITY ESTIMATE AS 30 KT. THE INITIAL MOTION ESTIMATE FOR THIS ADVISORY IS AN UNCERTAIN 315/03KT. UNFORTUNATELY...FORECAST TRACK GUIDANCE FOR NINE-C REMAINS UNRELIABLE...IF IT IS AVAILABLE. AS A RESULT...WE FEEL COMPELLED TO FOLLOW THE PREVIOUS OFFICIAL TRACK...WITH A CONSIDERABLE REDUCTION IN FORWARD MOTION. THIS APPEARS TO BE THE COURSE OF LEAST REGRET UNTIL WE ARE ABLE TO GET MORE RELIABLE TRACK GUIDANCE LATER TONIGHT OR ON THURSDAY. NINE-C IS EXPECTED TO DEVELOP SLOWLY...IF AT ALL...DUE TO THE STRONG EASTERLY SHEAR IN THE 25 TO 30 KT RANGE DEPICTED BY SHIPS. IF THIS SYSTEM AVOIDS DISSIPATION...IT IS FORECAST TO REACH TROPICAL STORM INTENSITY BY DAY 4 AS IT CROSSES THE INTERNATIONAL DATE LINE INTO THE WARM WATERS OF THE NORTHWESTERN PACIFIC OCEAN. FORECAST POSITIONS AND MAX WINDS INIT 31/0900Z 2.5N 175.8W 30 KT 35 MPH 12H 31/1800Z 2.7N 176.2W 30 KT 35 MPH 24H 01/0600Z 3.0N 176.7W 30 KT 35 MPH 36H 01/1800Z 3.3N 177.3W 30 KT 35 MPH 48H 02/0600Z 3.6N 177.9W 30 KT 35 MPH 72H 03/0600Z 4.1N 179.0W 30 KT 35 MPH 96H 04/0600Z 4.6N 180.0E 35 KT 40 MPH 120H 05/0600Z 5.0N 178.7E 40 KT 45 MPH $$ FORECASTER HOUSTON