WDPN33 PGTW 060300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 11W (NANGKA) WARNING NR 
11//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM 11W (NANGKA), LOCATED APPROXIMATELY 132 NM
NORTHWEST OF UJELANG, HAS TRACKED WEST-NORTHWESTWARD AT 12 KNOTS
OVER THE PAST SIX HOURS. THE CURRENT POSITION IS BASED ON RECENT 
MULTISPECTRAL SATELLITE IMAGERY AND A 052332Z PGTW SATELLITE FIX.  
THE INTENSITY OF 60 KNOTS IS CONSISTENT WITH A CONSENSUS OF DVORAK 
SATELLITE INTENSITY ESTIMATES FROM MULTIPLE REPORTING AGENCIES. 
RECENT ANIMATED MULTISPECTRAL SATELLITE IMAGERY SHOWS PERSISTENT 
DEEP CONVECTION WRAPPING INTO THE LOW LEVEL CIRCULATION CENTER 
(LLCC), PARTICULARLY OVER THE EASTERN PORTION. THE SYSTEM HAS 
STEADILY INTENSIFIED OVER THE PAST SIX HOURS, FUELED BY LOW VERTICAL 
WIND SHEAR, PASSAGE OVER WARM WATER, AND IMPROVING OUTFLOW ENHANCED 
BY A TROPICAL UPPER TROPOSPHERIC TROUGH (TUTT) CELL TO THE 
NORTHEAST. TS 11W IS TRACKING ALONG THE PERIPHERY OF A SUBTROPICAL 
STEERING RIDGE TO THE NORTH.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE 
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TS 11W WILL CONTINUE TRACKING ALONG THE SUBTROPICAL STEERING 
RIDGE PERIPHERY THROUGH THE NEXT 72 HOURS. WESTWARD MOTION WILL 
GRADUALLY TRANSITION TO A MORE NORTHWESTWARD TRACK AS THE STEERING 
RIDGE REORIENTS AHEAD OF A DEVELOPING MID-LATITUDE TROUGH. CONTINUED 
INTENSIFICATION IS EXPECTED AS VERTICAL WIND SHEAR REMAINS GENERALLY 
FAVORABLE AND UPPER-LEVEL OUTFLOW IS ENHANCED BY THE TUTT CELL TO 
THE NORTHEAST. A PERIOD OF RAPID INTENSIFICATION IN THE NEAR TO 
MEDIUM TERM IS POSSIBLE AS UPPER LEVEL TROUGHING PROVIDES THE 
POTENTIAL FOR SIGNIFICANTLY INCREASED OUTFLOW ALOFT. DYNAMIC MODEL 
GUIDANCE REMAINS IN GENERALLY GOOD AGREEMENT REGARDING THE FORECAST 
TRACK THROUGH TAU 72, WITH THE UKMET MODEL PRESENTING AS A POLEWARD 
OUTLIER FROM THE PRIMARY MODEL GROUPING. THE CURRENT TRACK FORECAST 
FOR THIS PERIOD LIES CLOSE TO THE MULTI-MODEL CONSENSUS AND THE 
PREVIOUS JTWC FORECAST.
   C. IN THE EXTENDED PERIOD, STORM MOTION IS EXPECTED TO SLOW AS A 
DEVELOPING MID-LATITUDE TROUGH BEGINS WEAKENING THE STEERING RIDGE. 
FUTHER INTENSIFICATION IS ANTICIPATED AS ENVIRONMENTAL CONDITIONS 
REMAIN FAVORABLE, PARTICULARLY WITH POLEWARD OUTFLOW POTENTIAL 
IMPROVING AHEAD OF THE DEVELOPING MID-LATITUDE TROUGH. DYNAMIC MODEL 
GUIDANCE HAS DIVERGED A BIT IN THE EXTENDED PERIOD AS EACH MODEL 
PRESENTS A DIFFERENT DEPICTION OF THE ANTICIPATED SLOWING AND A 
POTENTIAL POLEWARD TURN FOLLOWING TAU 120. HOWEVER, MODEL SPREAD 
REMAINS SMALL ENOUGH, AND THE SYNOPTIC SITUATION IS SUFFICIENTLY 
STRAIGHTFORWARD, TO LEND HIGH CONFIDENCE TO THE CURRENT JTWC 
FORECAST TRACK.//
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