WDPN31 PGTW 220900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 07W (NORU) WARNING NR 
007//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS 
   TROPICAL STORM (TS) 07W (NORU), LOCATED APPROXIMATELY 245 NM 
NORTH OF MINAMI TORI SHIMA, HAS TRACKED WESTWARD AT 05 KNOTS OVER 
THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS 
AN OBLONG CONVECTIVE MASS OBSCURING THE IMPROVED LOW-LEVEL 
CIRCULATION CENTER (LLCC). A 220528Z SSMIS 91GHZ COLOR COMPOSITE 
IMAGE INDICATES A DEFINED CENTER POSITIONED ON THE SOUTHWEST EDGE OF 
THE DEEP CONVECTIVE MASS WITH BROADER BANDING EVIDENT. UPPER-LEVEL 
ANALYSIS REVEALS A POINT SOURCE OVER THE SYSTEM WITH LOW TO MODERATE 
VERTICAL WIND SHEAR, AND EXCELLENT POLEWARD OUTFLOW INTO THE BROAD 
UPPER-LOW ASSOCIATED WITH TS 09W. THE CURRENT INTENSITY IS ASSESSED 
AT 45 KNOTS BASED ON DVORAK ESTIMATES RANGING FROM 35 TO 55 KNOTS, 
CONSISTENT WITH A RECENT SATCON ESTIMATE OF 44 KNOTS. TS 07W IS 
TRACKING SLOWLY WESTWARD ALONG THE SOUTHWEST PERIPHERY OF THE 
SUBTROPICAL RIDGE (STR).       
3. FORECAST REASONING.
   A. NO CHANGE IN THE FORECAST PHILOSOPHY SINCE THE PREVIOUS 
PROGNOSTIC REASONING.
   B. TS 07W IS FORECAST TO TRACK WESTWARD THROUGH TAU 12 THEN THE 
SYSTEM IS EXPECTED TO SLOW AND BECOME QUASI-STATIONARY THROUGH TAU 
48 DUE TO A COMBINATION OF TWO PRIMARY FACTORS. THE FIRST FACTOR IS 
THAT THE STR WILL WEAKEN EAST OF JAPAN DUE TO THE PRESENCE OF A 
BROAD LOW PRESSURE AREA. THE SECOND FACTOR IS RELATED TO THE 
APPROACH AND TRACK OF TS 09W (KULAP), WHICH IS FORECAST TO CLOSE 
WITHIN 400 NM BY TAU 48 RESULTING IN BINARY INTERACTION. TS 07W IS 
FORECAST TO INTENSIFY THROUGH TAU 72 UNDER FAVORABLE CONDITIONS TO A 
PEAK INTENSITY OF 80 KNOTS. DYNAMIC GUIDANCE IS UNANIMOUS IN 
SUPPORTING THE CURRENT FORECAST SCENARIO, INCLUDING BINARY 
INTERACTION AFTER TAU 48. 
   C. IN THE EXTENDED FORECAST PERIOD, TS 09W WILL APPROACH WITHIN 
240 NM BY TAU 72 AND 215 NM BY TAU 96. CONSEQUENTLY, TS 07W SHOULD 
BEGIN BINARY INTERACTION WITH A CYCLONIC TRACK INTO THE SOUTHERN 
PERIPHERY OF TS 09W. THIS SHOULD RESULT IN A MARKED WEAKENING PHASE 
WHERE 07W WEAKENS TO 65 KNOTS OR LOWER BY TAU 120. IN GENERAL, DUE 
TO THE COMPLEX INTERACTION BETWEEN THE TWO SYSTEMS, THERE IS LOW 
CONFIDENCE IN THE JTWC FORECAST TRACK. ADDITIONALLY, THERE IS HIGH 
UNCERTAINTY IN THE INTENSITY FORECAST DUE TO THE CLOSE PROXIMITY OF 
TS 09W AND THE EXPECTED DISRUPTION OF UPPER-LEVEL OUTFLOW AND LOW-
LEVEL FLOW.//
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