Tropical Storm MALAKAS Advisory 4月14日

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 02W (MALAKAS)
WARNING NR 028//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
   INITIAL POSITION: 19.7N 137.6E
   INITIAL INTENSITY: 115 KTS
   GEOGRAPHIC REFERENCE: 369 NM SOUTHWEST OF IWO TO
   MOVEMENT PAST 6 HOURS: NORTHWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: 38 FEET
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS SLIGHT
EROSION OF THE NOW 18NM EYEWALL, WITH A MAJORITY OF THE CONVECTIVE
ACTIVITY REMAINING ON THE EASTERN SIDE OF THE SYSTEM AS SEEN ON THE
131639Z AMSR2 89GHZ MICROWAVE IMAGE. THE INITIAL POSITION IS PLACED
WITH HIGH CONFIDENCE USING EXTRAPOLATION FROM THE PREVIOUSLY
MENTIONED IMAGE AND THE WELL-DEFINED 20NM EYE ON THE EIR LOOP. THE
INITIAL INTENSITY IS LOWER THAN THE AUTOMATED DVORAK TECHNIQUE AND
IS MORE IN RELATION WITH MULTIPLE AGENCY DVORAK CURRENT INTENSITY
ESTIMATES, WHICH ARE BETWEEN T5.0 TO T5.5 (90-102KTS). OVER THE
PAST FEW HOURS, THE EYE TEMPS HAVE COOLED SLIGHTLY FROM 14C TO NOW
9C. THIS GIVES THE FIRST HINT AT THE DOWNWARD TREND, ALONG WITH
WARMING CLOUD TOPS. THE OVERALL ENVIRONMENT IS MARGINALLY
FAVORABLE, WITH STRONG POLEWARD OUTFLOW, WARM SSTS, AND LOW
VERTICAL WIND SHEAR. HOWEVER, THE DRY, STABLE AIR, WEST OF THE
SYSTEM IS BEGINNING TO WRAP AROUND THE SOUTHERN SIDE, INHIBITING
THE OUTFLOW TO THE WEST AND SOUTHWEST.
INITIAL WIND RADII BASIS: PERSISTENCE
CURRENT STEERING MECHANISM: WESTERN SIDE OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) TO THE EAST.
AGENCY DVORAK AND AUTOMATED FIXES:
   PGTW: T5.5 - 102 KTS
   RJTD: T5.5 - 102 KTS
   RCTP: T5.0 - 90 KTS
   CIMSS SATCON: 118 KTS AT 131635Z
   CIMSS ADT: 127 KTS AT 131740Z
FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 5-10 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: STRONG POLEWARD
   OTHER FACTORS: LIMITED OUTFLOW AND SIGNIFICANT DRY AIR REMAINS
ON THE WESTERN SIDE OF THE CIRCULATION.
ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: MEDIUM
   INITIAL WIND RADII: LOW
3. FORECAST REASONING.
SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.
FORECAST DISCUSSION: TY MALAKAS IS TRACKING NORTHWESTWARD UNDER THE
STEERING INFLUENCE OF THE STR. MAINTAINING THE PEAK INTENSITY OF
115 KNOTS. HOWEVER, THE ENVIRONMENTAL CONDITIONS ARE ERODING AS THE
SYSTEM MIGRATES TO THE NORTHEAST. THE DRY AIR ON THE WEST SIDE IS
NOW WRAPPING AROUND THE OUTER CORE AND WILL BEGIN WRAPPING AROUND
THE INNER CORE WITHIN THE NEXT 12 TO 24 HOURS. SHEAR REMAINS LOW AT
THIS TIME, BUT AS THE SYSTEM CONTINUES MOVING INTO THE PREVAILING
WESTERLIES, IT WILL BEGIN EXPERIENCING MORE DRY AIR ENTRAINMENT.
THERE IS A BIT OF UPWELLING NOTICED BY THIS STRONG SYSTEM AND THOSE
DECREASING TEMPERATURES WILL CONTINUE BY TAU 12 AS THE SYSTEM MOVES
FURTHER NORTH. THESE LOWER SEA SURFACE TEMPERATURES WILL STIFLE THE
SYSTEMS AVAILABLE HEAT CONTENT AND BEGIN THE EXTRATROPICAL
TRANSITION (ETT) BY TAU 36. STRONGER SHEAR WILL BEGIN IMPACTING THE
SYSTEM BY TAU 48, WHICH WILL RAPIDLY ERODE THE SYSTEM AS IT NEARS
THE COMPLETION OF THE ETT. TRANSITION TO A STRONG GALE-FORCE COLD-
CORE EXTRATROPICAL LOW-PRESSURE AREA IS EXPECTED TO BE COMPLETE
BETWEEN TAU 48 AND TAU 72, AS THE SYSTEM IS EMBEDDED WITHIN THE
200MB POLAR FRONT JET STREAM AND DEVELOPS STRONG FRONTAL
CHARACTERISTICS.
MODEL DISCUSSION: DETERMINISTIC AND ENSEMBLE TRACK GUIDANCE IS IN
TIGHT AGREEMENT THROUGH THE DURATION OF THE FORECAST PERIOD, WITH
MINIMAL CROSS-TRACK SPREAD WITH A VERY NARROW 132NM AT TAU 72.
ACROSS-TRACK SPREAD REMAINS VERY CONSISTENT, WITH THE CONSENSUS
MEMBERS TIGHTLY PACKED EVEN AT TAU 72. THERE IS HIGH CONFIDENCE IN
THE JTWC TRACK FORECAST. AVAILABLE INTENSITY GUIDANCE REMAINS
LIMITED DURING THIS CYCLE, BUT OVERALL THE AVAILABLE MODELS ALL
CONCUR ON RAPID WEAKENING THROUGH THE FORECAST PERIOD. THE JTWC
FORECAST CONCURS WITH THE OVERALL SCENARIO BUT DEPARTS FROM THE
CONSENSUS MEAN, WITH A SLIGHTLY SLOWER RATE OF WEAKENING.
CONFIDENCE IN THE INTENSITY FORECAST IS ASSESSED AS MEDIUM.
FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: HIGH
   INTENSITY 0 - 72 HR: MEDIUM//
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