WDPN31 PGTW 212100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 07W (MEKKHALA) WARNING NR 013//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 17.3N 128.9E
   INITIAL INTENSITY: 80 KTS
   GEOGRAPHIC REFERENCE: 555 NM SOUTH OF KADENA AB
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 16 KTS
   SIGNIFICANT WAVE HEIGHT: 40 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TYPHOON
(TY) 07W (MEKKHALA) ATTEMPTING TO FORM AN EYE AS CONVECTIVE SPIRAL
BANDING CONTINUES TO WRAP INTO THE CENTER, BUT NO DISCERNABLE EYE
HAS MANAGED TO PERSIST. THE INITIAL POSITION IS PLACED WITH HIGH
CONFIDENCE BASED ON A 211711Z 89 GHZ ATMS IMAGE DEPICTING A
MICROWAVE EYE, IN LINE WITH THE WEAK TEMPORARY EYES OBSERVABLE IN
EIR SATELLITE IMAGERY. THE INITIAL INTENSITY IS ALSO ASSESSED WITH
HIGH CONFIDENCE BASED ON WIDESPREAD AGREEMENT OF THE CIMSS
OBJECTIVE ESTIMATES AND AGENCY DVORAK FIXES LISTED BELOW. TY 07W IS
ASSESSED TO BE CURRENTLY EXPERIENCING RAPID INTENSIFICATION (RI),
AS ENVIRONMENTAL ANALYSIS SHOWS TY 07W IN A HIGHLY FAVORABLE
ENVIRONMENT OF WARM (29-30 C) SEA SURFACE TEMPERATURES (SSTS), LOW
(10-15 KTS) VERTICAL WIND SHEAR (VWS), AND STRONG RADIAL OUTFLOW
ALOFT.

INITIAL WIND RADII BASIS: ADJUSTED WIND RADII BASED ON 211206Z
METOP-C ASCAT PASS.

CURRENT STEERING MECHANISM: WESTWARD EXTENSION OF SUBTROPICAL RIDGE
(STR) CENTERED TO THE NORTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.5 - 77 KTS
   RJTD: T5.0 - 90 KTS
   RCTP: T4.0 - 65 KTS
   KNES: T4.5 - 77 KTS
   CIMSS SATCON: 81 KTS AT 211800Z
   CIMSS ADT: 79 KTS AT 211800Z
   CIMSS AIDT: 83 KTS AT 211800Z
   CIMSS D-MINT: 79 KTS AT 211627Z
   CIMSS D-PRINT: 68 KTS AT 211730Z

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

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: HIGH
   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
WEST-NORTHWESTWARD UNTIL TAU 24 TO 36  UNDER THE INFLUENCE OF A
SUBTROPICAL RIDGE (STR) CENTERED TO THE NORTHEAST. AFTER THAT
POINT, THE STR WILL WEAKEN TO THE NORTH OF THE SYSTEM CAUSING A
POLEWARD TURN, ACCOMPANIED WITH A SLOWING IN TRACK SPEED. AT TAU
72, TY 07W IS EXPECTED TO TURN NORTH-NORTHEASTWARD AND PASS WEST OF
OKINAWA BETWEEN TAUS 72 AND 96, AND TRACK TOWARDS SOUTHERN KYUSHU
AT THE END OF THE FORECAST PERIOD. IN REGARDS TO THE INTENSITY
FORECAST, TY 07W IS FORECAST TO CONTINUE RI OVER THE NEXT 24 HOURS
AND REACH ITS PEAK INTENSITY AT TAU 36, COINCIDING WITH THE
POLEWARD TURN. AFTER TAU 36, TY 07W IS FORECAST TO EXPERIENCE A
SHARP DECREASE IN INTENSITY AS THE SYSTEM ENCOUNTERS MARGINAL TO
HOSTILE ENVIRONMENTAL CONDITIONS OF OVER 30 KTS VWS, A BROAD AREA
OF DRY AIR, AND POSSIBLE COOLER SSTS THAT COULD BE UPWELLED IN THE
WAKE OF TY MEKKHALA. OF NOTE, THERE IS SOME UNCERTAINTY BETWEEN THE
GFS AND ECMWF MODELS IN REGARDS TO HOW MUCH VWS AND DRY AIR
ENTRAINMENT WILL IMPACT THE SYSTEM, WITH ECMWF HAVING A MUCH FASTER
DEGRADATION TREND THAN GFS. THIS IS ALSO DEPENDENT ON THE STRENGTH
OF TY 07W WHEN IT MEETS THESE MORE HOSTILE CONDITIONS, AS A
STRONGER STORM COULD STAY INSULATED FROM 20-25 KT VWS AND DRY AIR
ENTRAINMENT.

MODEL DISCUSSION: TRACK MODEL GUIDANCE IS IN GOOD AGREEMENT
THROUGHOUT THE FORECAST PERIOD WITH THE ONLY OUTLIERS BEING JGSM,
GALWEM, AND GFS THAT TRACK TY 07W MUCH MORE POLEWARD WITHOUT A NNE
TURN. USING AN ADJUSTED MULTI-MODEL CONSENSUS EXCLUDING THOSE THREE
MODELS, THE OFFICIAL JTWC FORECAST TRACK IS LAID WITH HIGH
CONFIDENCE THROUGHOUT THE FORECAST PERIOD, CLOSE TO THE MULTI-MODEL
AND ADJUSTED CONSENSUS, AND JUST SLOWER THAN THE EXPERIMENTAL AI
CONSENSUS. INTENSITY MODEL GUIDANCE CONTINUES TO BE SPREAD AT THE
POINT OF PEAK INTENSITY. THE OFFICIAL JTWC INTENSITY FORECAST IS
ASSESSED WITH MEDIUM CONFIDENCE OUT TO TAU 72 BASED ON THE CURRENT
RI BEING OBSERVED, AND POTENTIAL EYE FORMATION THAT WILL AID
INTENSIFICATION. THE TAU 72 TO 120 INTENSITY FORECAST IS ASSESSED
WITH LOW CONFIDENCE BASED ON THE UNCERTAINTY BETWEEN MODELS IN
REGARDS TO THE CONTRIBUTING ENVIRONMENTAL FACTORS, AS DISCUSSED
ABOVE. 

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