Tropical Storm HINNAMNOR Advisory So, 04.09.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 12W (HINNAMNOR) WARNING NR 028//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
   INITIAL POSITION: 26.1N 124.5E
   INITIAL INTENSITY: 105 KTS
   GEOGRAPHIC REFERENCE: 179 NM WEST OF KADENA AB
   MOVEMENT PAST 6 HOURS: NORTHWARD AT 10 KTS
   SIGNIFICANT WAVE HEIGHT: 45 FEET
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS THAT TY 12W
HAS RAPIDLY CONSOLIDATED AND INTENSIFIED OVER THE PAST SIX HOURS,
WITH A SYMMETRIC 45-NM CORE OF DEEP CONVECTION AND A 10-NM EYE.
ANIMATED RADAR DATA AND A 032242Z GMI 89GHZ MICROWAVE IMAGE
REVEALED THE INNER CORE, COCOONED WITHIN A MUCH LARGER,
APPROXIMATELY 120NM DIAMETER SECONDARY EYEWALL. SOMEWHAT
SURPRISINGLY, WITH SUCH A STRONG SECONDARY EYEWALL, THE INNER CORE
AND EYE HAVE BEEN ABLE TO SUSTAIN AND GROW STRONGER AND SHOW NO
SIGN OF IMMINENT EROSION DUE TO BEING CUTOFF FROM ANY SIGNIFICANT
INFLOW. ITS ALMOST AS IF THERE IS A VERY SMALL ANNULAR TYPHOON
NESTED INSIDE A LARGER TROPICAL CYCLONE LIKE A MATRYOSHKA DOLL.
WHILE THE INNER CORE IS VERY SMALL, THE GALE-FORCE WIND FIELD
CONTINUES TO EXPAND AND NOW ENCOMPASSING THE MAJORITY OF THE EAST
CHINA SEA. THE SYSTEM IS WOBBLING GENERALLY NORTHWARD WITH THE
TRACK MADE GOOD JUST A HAIR WEST OF DUE NORTH OVER THE PAST SIX
HOURS AND HAS REACHED CPA TO OKINAWA. THE INITIAL POSITION IS
ASSESSED WITH HIGH CONFIDENCE BASED ON THE MSI, RADAR AND MICROWAVE
EYES. THE INITIAL INTENSITY IS ASSESSED AT 105 KNOTS WITH HIGH
CONFIDENCE, HEDGED ABOVE THE BULK OF THE AGENCY FIXES AS A NOD TO
THE SATCON, AND EXPERIMENTAL CIMSS DEEP MULTINET (110KTS) AND
OPEN-AIIR (107KTS) AND THE RAPID CLEARING OF A NEARLY PINHOLE EYE.
INITIAL WIND RADII BASIS: PERSISTENCE
CURRENT STEERING MECHANISM: WESTERN PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) TO THE EAST
AGENCY DVORAK AND AUTOMATED FIXES:
   PGTW: T5.0 - 90 KTS
   RJTD: T5.0 - 90 KTS
   KNES: T6.0 - 115 KTS
   CIMSS SATCON: 106 KTS AT 032217Z
   CIMSS ADT: 97 KTS AT 040010Z
FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG POLEWARD AND EQUATORWARD
   OTHER FACTORS: CONCENTRIC EYEWALL, DRY AIR ENTRAINMENT OFF
TAIWAN
ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: HIGH
   INITIAL WIND RADII: LOW
3. FORECAST REASONING.
SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.
FORECAST DISCUSSION: HAVING MOVED NORTH INTO THE WARM WATERS OF THE
EAST CHINA SEA THIS MORNING, TY 12W HAS CLEARLY GOTTEN ITS ACT
TOGETHER AND BEGUN TO RAPIDLY INTENSIFY UNDER FAVORABLE
ENVIRONMENTAL CONDITIONS. THE SYSTEM WILL CONTINUE TO TRACK
GENERALLY NORTHWARD, WITH SOME CONTINUED DEVIATIONS RIGHT AND LEFT
OF DUE NORTH DUE TO WOBBLE, ALONG THE WESTERN SIDE OF THE DEEP
STEERING RIDGE TO THE EAST THROUGH THE NEXT 12 HOURS OR SO. THEN
AROUND TAU 24, IT WILL MAKE A SHARP TURN TO THE NORTHEAST AS IT
ROUNDS THE RIDGE. ONCE FIRMLY ON THE NORTHEAST TRACK, ITS OFF TO
THE RACES, WITH TRACK SPEEDS DOUBLING WITHIN 24 HOURS AS THE SYSTEM
MOVES ALONG THE TIGHT DEEP-LAYER GRADIENT BETWEEN THE RIDGE TO THE
EAST AND AN UNSEASONABLY STRONG UPPER-LEVEL LOW AND TROUGH MOVING
IN FROM THE WEST. WHILE THERE REMAINS SOME DRY AIR ENTRAINMENT
FLOWING OFF TAIWAN INTO THE SOUTHWESTERN SIDE OF THE STORM, THE
ATMOSPHERE DOWN TRACK IS MORE MOIST AND THERE IS PLENTY OF WARM WATER
AHEAD. SHEAR IS ALSO EXPECTED TO REMAIN AT OR BELOW 10 TO 15 KNOTS
MAX FOR THE NEXT 24 TO 36 HOURS. LASTLY, WHILE OUTFLOW TO THE WEST
IS STILL LIMITED, THIS IS MORE THAN OFFSET BY THE VERY STRONG
OUTFLOW TO THE EAST AND EQUATORWARD. THE OUTFLOW PATTERN IS SET TO
BECOME EVEN BETTER OVER THE NEXT 24 HOURS AS A JET MAXIMUM SKIRTS
ACROSS THE BOHAI GULF, AND TY 12W ESTABLISHES A TAP INTO THE
DIVERGENT RIGHT FRONT EXIT REGION OF THE JET MAX. IN OTHER WORDS,
THE ENVIRONMENT SUPPORTS ADDITIONAL INTENSIFICATION THROUGH TAU 36.
HOWEVER, THE CURRENT CONCENTRIC EYEWALL SETUP, AND INCREASING
M-PERC EYEWALL REPLACEMENT CYCLE (ERC) PROBABILITIES SUGGEST THE
START OF AN ERC IN THE NEAR FUTURE. SO THE PEAK WILL PROBABLY OCCUR
WITHIN THE NEXT 12 HOURS AT 115 KNOTS, POTENTIALLY SLIGHTLY HIGHER,
BUT THEN BE ARRESTED BY THE ERC. DUE TO THE SPEED OF ADVANCE, AND
MOVEMENT OVER STEADILY COOLER WATERS, IT IS UNLIKELY THAT TY 12W
WILL REINTENSIFY MUCH AFTER THE COMPLETION OF THE ERC. AFTER TAU 36
THE PARTY IS OVER, AS SHEAR DRAMATICALLY AND SHARPLY INCREASES AND
OVERCOMES THE VERY IMPRESSIVE POLEWARD OUTFLOW AND THE SYSTEM
BEGINS TO WEAKEN WHILE BEGINNING EXTRA-TROPICAL TRANSITION (ETT).
WHILE WEAKENING AS A TROPICAL CYCLONE, THE STRONG MID-LATITUDE
DYNAMICS ASSOCIATED WITH THE DEEP TROUGH TO THE NORTHWEST WILL
MANAGE TO KEEP THE INTENSITY UP AS THE SYSTEM MAKES LANDFALL ALONG
THE COAST OF SOUTH KOREA AROUND TAU 48. THE SYSTEM WILL THEN MOVE
RAPIDLY INTO THE SEA OF JAPAN AND TRANSITION TO A WARM SECLUSION
TYPE EXTRA-TROPICAL LOW AS EARLY AS TAU 60.
MODEL DISCUSSION: TRACK GUIDANCE REMAINS IN VERY GOOD AGREEMENT AND
VERY CONSISTENT WITH THE PREVIOUS RUNS. SPREAD IS MINIMAL, LESS
THAN 100NM THROUGH THE FORECAST PERIOD, THOUGH ALONG-TRACK SPREAD
INCREASES SIGNIFICANTLY AFTER TAU 48 AS THE SYSTEM GOES
EXTRA-TROPICAL. THE JTWC FORECAST ALSO REMAINS CONSISTENT WITH THE
PREVIOUS FORECAST AND THE MULTI-MODEL CONSENSUS WITH HIGH
CONFIDENCE. INTENSITY GUIDANCE IS IN POOR AGREEMENT, WITH SEVERAL
OF THE RAPID INTENSIFICATION (RI) AIDS TRIGGERING WITH THIS RUN, UP
TO RI45 WHICH WOULD PEAK AT 150 KNOTS AT TAU 36. MEANWHILE THE
REMAINDER OF THE INTENSITY PACKAGE IS NOT IMPRESSED BY TY 12W AND
SHOW STAGNATION OR IMMEDIATE AND CONTINUED WEAKENING, WITH THE
COAMPS-TC NOW DOING A FLIP-FLOP AND NOW COMMITTED TO IMMEDIATE
WEAKENING TO 75 KNOTS BY TAU 24, AN UNLIKELY SOLUTION. THE JTWC
FORECAST TRACKS THE RI GUIDANCE THROUGH TAU 12 BUT THEN REJOINS THE
HIGHER END OF THE PACK BY TAU 24 THEN REMAINS ON THE HIGH EDGE OF
THE GUIDANCE THROUGH THE REMAINDER OF THE FORECAST PERIOD.
CONFIDENCE IS MEDIUM TO LOW DUE TO THE UNCERTAINTY IN THE TIMING
AND IMPACTS OF THE ERC AND THE SUBSEQUENT ALIGNMENT WITH THE OTHER
HIGHLY FAVORABLE FACTORS.
FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: HIGH
   INTENSITY 0 - 72 HR: MEDIUM//
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