WDPN31 PGTW 250300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 07W (MEKKHALA) WARNING NR 
026//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 23.7N 125.3E
   INITIAL INTENSITY: 50 KTS
   GEOGRAPHIC REFERENCE: 216 NM SOUTHWEST OF KADENA AB
   MOVEMENT PAST 6 HOURS: NORTH-NORTHEASTWARD AT 11 KTS
   SIGNIFICANT WAVE HEIGHT: 26 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL
STORM (TS) 07W (MEKKHALA) WITH A PARTIALLY EXPOSED LOW LEVEL
CIRCULATION (LLCC) WHILE HIGH (25-30 KTS) NORTHEASTERLY VERTICAL
WIND SHEAR (VWS) IS EVIDENT AS THE DECOUPLING UPPER LEVEL
CIRCULATION AND CIRRUS OUTFLOW REMAIN CONFINED TO THE SOUTHERN
SEMICIRCLE OF THE SYSTEM. OTHER DETRIMENTAL ENVIRONMENTAL FACTORS
OF MODERATE EQUATORWARD OUTFLOW ALOFT AND AN AREA OF DRY AIR TO THE
NORTH ARE OFFSET ONLY BY THE WARM (28-29 C) SEA SURFACE
TEMPERATURES (SSTS). THE INITIAL POSITION IS ASSESSED WITH HIGH
CONFIDENCE BASED ON A COMBINATION OF 242216Z 37 GHZ WSFM IMAGE
AND A 242130Z SAR NORMALIZED RADAR CROSS SECTION IMAGE WHICH BOTH
DEPICT THE BROAD LOW LEVEL CIRCULATION. THE INITIAL INTENSITY IS
ASSESSED WITH HIGH CONFIDENCE BASED ON THE AGREEMENT OF AGENCY
DVORAK FIXES AND CIMSS OBJECTIVE ESTIMATES LISTED BELOW.

INITIAL WIND RADII BASIS: ADJUSTED WIND RADII BASED ON 242130Z SAR
IMAGE.

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   RJTD: T3.5 - 55 KTS
   RCTP: T3.5 - 55 KTS
   KNES: T3.0 - 45 KTS
   CIMSS ADT: 49 KTS AT 250000Z
   CIMSS AIDT: 47 KTS AT 250000Z
   CIMSS D-MINT: 55 KTS AT 242218Z
   CIMSS D-PRINT: 49 KTS AT 250000Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 25-30 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: MODERATE EQUATORWARD

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: TS 07W CONTINUES TO WOBBLE NORTH-NORTHEASTWARD
AND INCREASE IN TRACK SPEED AS IT ROUNDS THE AXIS OF THE
SUBTROPICAL RIDGE (STR) CENTERED TO THE EAST. TS MEKKHALA IS
FORECAST TO CPA OKINAWA ROUGHLY 35 NM OFF ITS WEST COAST SHORTLY
AFTER TAU 24 AND CONTINUE ON TO TRACK JUST OFF THE SOUTH COAST OF
KYUSHU AND HONSHU. TS MEKKHALA IS EXPECTED TO CONTINUE INCREASING
IN TRACK SPEED AS IT COMPLETES ROUNDING THE STR AXIS AND BEGINS
EXTRATROPICAL TRANSITION (ETT) AT TAU 48 AS IT ENCOUNTERS STRONGER
UPPER-LEVEL WESTERLIES. ETT IS EXPECTED TO COMPLETE BY TAU 72 AS
THE SYSTEM BECOMES EMBEDDED UNDERNEATH THE JET. IN REGARDS TO
INTENSITY, TS 07W IS FORECAST TO STEADILY DECREASE IN INTENSITY,
WITH A BRIEF PLATEAU FROM TAUS 12 TO 24 AS VWS IS EXPECTED TO
BRIEFLY ABATE TO  15-20 KTS BEFORE INCREASING AGAIN TO 30 KTS OR
MORE FOR THE REMAINDER OF THE FORECAST PERIOD, CONTRIBUTING TO THE
STRONGER WEAKENING TREND THEREAFTER. FURTHERMORE, TS MEKKHALA IS
EXPECTED TO ENCOUNTER 26-27 C SSTS AROUND TAU 48, WHICH WILL
DEPRIVE THE SYSTEM OF ANY FAVORABLE ENVIRONMENTAL CONDITIONS AS A
TROPICAL SYSTEM. HOWEVER, TS 07W IS FORECAST TO REMAIN AT TROPICAL
STORM LEVEL INTENSITY FOR THE DURATION OF THE FORECAST PERIOD AS IT
COMPLETES ETT.

MODEL DISCUSSION: TRACK MODEL GUIDANCE IS IN GOOD AGREEMENT WITH
THE EXCEPTION OF ECMWF AND GALWEM, WHICH WERE BOTH EXCLUDED FROM AN
ADJUSTED MULTI-MODEL CONSENSUS USED TO LAY THE FORECAST TRACK. THE
LARGEST AREA OF DISAGREEMENT IN THE TRACK MODELS REMAINS THE TRACK
SPEED, WITH A 320 NM ALONG-TRACK SPREAD BY TAU 72, EXCLUDING THE
OUTLIERS ECMWF AND GALWEM. THE OFFICIAL JTWC FORECAST TRACK IS LAID
WITH HIGH CONFIDENCE, WITH TRACK AND SPEED PLACED CLOSE TO THE
ADJUSTED MULTI-MODEL CONSENSUS AND EXPERIMENTAL AI CONSENSUS.
INTENSITY MODEL GUIDANCE REMAINS AT A 15-20 KT SPREAD THROUGHOUT
THE REMAINDER OF THE FORECAST PERIOD, AND THUS THE OFFICIAL JTWC
FORECAST INTENSITY IS ASSESSED WITH MEDIUM CONFIDENCE, ABOVE THE
MULTI-MODEL CONSENSUS.

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