WDIO31 PGTW 142100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 07A (SEVEN) WARNING NR 
001//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 13.6N 68.6E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 678 NM SOUTH OF KARACHI, PAKISTAN
   MOVEMENT PAST 6 HOURS: WESTWARD AT 06 KTS
   SIGNIFICANT WAVE HEIGHT: 11 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS RAGGEDLY
FLARING DEEP CONVECTION ASSOCIATED WITH A LOW-LEVEL CIRCULATION
CENTER (LLCC). THE INITIAL POSITION IS PLACED WITH MEDIUM
CONFIDENCE BASED ON A 141656Z AMSU-B 89GHZ MICROWAVE IMAGE. THE
INITIAL INTENSITY IS ASSESSED WITH HIGH CONFIDENCE BASED ON
SCATTEROMETERY AND IS CORROBORATED BY SUBJECTIVE DVORAK INTENSITY
ESTIMATES RANGING FROM T1.5 TO T3.0.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   KNES: T3.0 - 45 KTS
   DEMS: T1.5 - 25 KTS

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 5-10 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: MODERATE POLEWARD

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THIS INITIAL PROGNOSTIC REASONING
MESSAGE ESTABLISHES THE FORECAST PHILOSOPHY.

FORECAST DISCUSSION: TROPICAL CYCLONE (TC) 07A IS TRACKING TOWARD
THE WEST-NORTHWEST UNDER THE STEERING INFLUENCE OF A WEAK STR TO
THE NORTH. IT RAPIDLY ORGANIZED OVER THE PAST 24 HOURS, LIKELY
REACHING A PEAK INTENSITY PRIOR TO THIS FIRST WARNING.
ENVIRONMENTAL CONDITIONS ARE ONLY MARGINALLY FAVORABLE FOR
DEVELOPMENT AT THIS TIME, CONSISTING OF LOW VERTICAL WIND SHEAR AND
WARM SEA SURFACE TEMPERATURES OFFSET BY LIMITED POLEWARD OUTFLOW
SUPPORTING THE RAGGED FLARING CONVECTION. OVER THE NEXT 12 TO 24
HOURS, VERTICAL WIND SHEAR IS EXPECTED TO RAPIDLY INCREASE TOGETHER
WITH ENTRAINMENT OF DRY AIR. AS SUCH, TC 07A IS EXPECTED TO BE
RATHER SHORT LIVED. WEAKENING FOLLOWED BY DISSIPATION OVER WATER
SHOULD OCCUR BY TAU 24.

MODEL DISCUSSION: NUMERICAL MODEL TRACKERS ARE TIGHTLY CLUSTERED
OVER THE NEXT 24 HOURS, SO THERE IS HIGH CONFIDENCE IN THE JTWC
TRACK FORECAST. ALL INTENSITY MODELS PROJECT A MAINTENANCE OF
INTENSITY OVER THE NEXT 12 HOURS, FOLLOWED BY WEAKENING BELOW
WARNING CRITERIA, SO THERE IS ALSO HIGH CONFIDENCE IN THE JTWC
INTENSITY FORECAST.

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: HIGH
   INTENSITY 0 - 72 HR: HIGH//
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