WDPN31 PGTW 210900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 07W (MEKKHALA) WARNING NR 011//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 16.1N 131.9E
   INITIAL INTENSITY: 65 KTS
   GEOGRAPHIC REFERENCE: 665 NM SOUTH-SOUTHEAST OF KADENA AB
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 13 KTS
   SIGNIFICANT WAVE HEIGHT: 32 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TYPHOON (TY)
07W (MEKKHALA) WITH STRONG RADIAL OUTFLOW AND ACCOMPANYING CIRRUS
FILAMENTS AND WELL-DEFINED SPIRAL BANDS OF DEEP CONVECTION.
ANALYSIS OF ANIMATED BRIGHTNESS TEMPERATURE REVEALS SIGNIFICANTLY
COOLING CLOUD TOPS AND A SYMMETRICAL CENTRAL DENSE OVERCAST (CDO).
ENVIRONMENTAL ANALYSIS REVEALS A HIGHLY FAVORABLE ENVIRONMENT,
CHARACTERIZED BY LOW (10-15 KTS) VERTICAL WIND SHEAR (VWS), WARM
(29-30 C) SEA SURFACE TEMPERATURES (SST), AND STRONG RADIAL OUTFLOW
AIDED BY A POINT SOURCE ALOFT. THE INITIAL POSITION IS PLACED WITH
MEDIUM CONFIDENCE BASED ON ANIMATED MSI SUPPORTED BY THE 210504Z
PARTIAL AMSR2 MICROWAVE IMAGE. THE INITIAL INTENSITY OF 65 KTS IS
ASSESSED WITH LOW CONFIDENCE BASED ON THE CIMSS INTENSITY ESTIMATES
AND AGENCY FIXES LISTED BELOW.

INITIAL WIND RADII BASIS: ADJUSTED 34 KT AND 50 KT RADII USING THE
210034Z ASCAT DATA.

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) CENTERED TO THE
NORTH

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   RJTD: T3.5 - 55 KTS
   RCTP: T3.5 - 55 KTS
   KNES: T4.0 - 65 KTS
   CIMSS SATCON: 69 KTS AT 210700Z
   CIMSS ADT: 74 KTS AT 210600Z
   CIMSS AIDT: 70 KTS AT 210600Z
   CIMSS D-MINT: 55 KTS AT 210442Z
   CIMSS D-PRINT: 59 KTS AT 210700Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE
   VWS: 10-15 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG RADIAL

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   INITIAL INTENSITY: LOW
   INITIAL WIND RADII: MEDIUM

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: TY 07W IS FORECAST TO CONTINUE TRACKING
NORTHWESTWARD FOR THE NEXT 36 HOURS WHILE IT REMAINS LOCATED ON THE
SOUTHERN PERIPHERY OF THE STEERING STR. BETWEEN TAU 36-48, 07W WILL
BEGIN TO ENCOUNTER A WEAKNESS IN THE RIDGE AND BEGIN TO CURVE
NORTH-NORTHWESTWARD. FROM TAU 48 TO TAU 72, MEKKHALA WILL ROUND THE
RIDGE AXIS, INDUCING A NORTH-NORTHEASTWARD TRAJECTORY FROM TAU 72
THROUGH THE END OF THE FORECAST. REGARDING INTENSITY, 07W IS
FORECAST TO RAPIDLY INTENSIFY (RI) WHILE IT REMAINS IN THE HIGHLY
FAVORABLE ENVIRONMENT. RI IS EXPECTED TO OCCUR FROM TAU 0 UNTIL TAU
24, FOLLOWED BY ADDITIONAL SIGNIFICANT INTENSIFICATION UNTIL
REACHING THE PEAK INTENSITY AT TAU 48. JUST BEFORE TAU 60, 07W WILL
ENTER A HOSTILE ENVIRONMENT, CHARACTERIZED BY HIGH (30-40 KTS) VWS
AND SIGNIFICANT DRY AIR, INDUCING DRASTIC WEAKENING. COOL WATER
UPWELLING IS ALSO POSSIBLE AROUND TAU 60 AS MEKKHALA SLOWS WHILE
ROUNDING THE RIDGE, FURTHER HASTENING THE WEAKENING TREND. 

MODEL DISCUSSION: DETERMINISTIC MODEL TRACK GUIDANCE IS IN STRONG
AGREEMENT IN THE NEAR-TERM FORECAST, WITH MINIMAL CROSS-TRACK OR
ALONG-TRACK SPREAD THROUGH TAU 60. FOLLOWING TAU 60, SIGNIFICANT
ALONG-TRACK SPREAD BECOMES EVIDENT AS MODELS STRUGGLE TO INTERPRET
THE RECURVATURE SCENARIO AND ASSOCIATED TRANSLATION SPEEDS. AS A
RESULT, THE JTWC TRACK FORECAST IS PLACED WITH HIGH CONFIDENCE FROM
TAU 0-72 AND MEDIUM CONFIDENCE FROM TAU 72-120. RELIABLE INTENSITY
GUIDANCE IS IMPROVING IN TERMS OF GENERAL AGREEMENT, BUT STILL
DEPICTING A LARGE RANGE BETWEEN 70-130 KTS AT THE TIME OF
FORECASTED PEAK INTENSITY. HAFS AND COAMPS-TC (GFS BOUNDARY
CONDITIONS) DEPICT RI, IN ADDITION TO SEVERAL JTWC RI AIDS REACHING
THRESHOLD. THE CIMSS AI-RI FORECAST HAS INCREASED TO 55 PERCENT
PROBABILITY OF 25 KT INTENSIFICATION WITHIN 24 HOURS, AND TO 48
PERCENT PROBABILITY OF 30 KT INTENSIFICATION WITHIN 24 HOURS,
FURTHER SUPPORTING THE JTWC RI FORECAST. GUIDANCE DISAGREES
SIGNIFICANTLY REGARDING THE WEAKENING TREND IN THE LATE-TERM
FORECAST. THE JTWC INTENSITY FORECAST LIES CLOSE TO THE HAFS
SOLUTION WITH MEDIUM CONFIDENCE FROM TAU 0-72 AND LOW CONFIDENCE
FROM TAU 72-120.

FORECAST CONFIDENCE:
   TRACK 00-72 HR: HIGH
   TRACK 72-120 HR: MEDIUM
   INTENSITY 00-72 HR: MEDIUM
   INTENSITY 72-120 HR: LOW//
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