WDPN31 PGTW 061500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 05W (PEIPAH) 
WARNING NR 15//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION (TD) 05W (PEIPAH), LOCATED APPROXIMATELY 
25 NM EAST-SOUTHEAST OF KOROR, PALAU, HAS TRACKED NORTHWESTWARD 
AT 12 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED 
SATELLITE IMAGERY DEPICTS THE DEEP CONVECTION SHEARED TO THE 
NORTHWEST OF A WEAK DEVELOPING LOW-LEVEL CIRCULATION CENTER (LLCC). 
A 061212Z METOP-B MICROWAVE IMAGE REVEALS FRAGMENTED CONVECTIVE 
BANDING OVER THE NORTHERN SEMI-CIRCLE WRAPPING INTO A DEFINED 
CENTER. THE CURRENT INTENSITY OF 30 KNOTS IS BASED ON A 061212Z 
ASCAT PASS SHOWING A 25 TO 30 KNOT CIRCULATION AS WELL AS DVORAK 
CURRENT INTENSITY ESTIMATES FROM PGTW AND RJTD. THE CURRENT POSITION 
IS BASED ON THE ABOVE ASCAT IMAGE WITH HIGH CONFIDENCE. TD 05W 
CONTINUES TO TRACK WEST-NORTHWESTWARD ALONG THE SOUTHERN PERIPHERY 
OF A DEEP-LAYERED SUBTROPICAL STEERING RIDGE TO THE NORTH. ALTHOUGH 
WARM SEA SURFACE TEMPERATURE (SST) IS CONDUCIVE FOR DEVELOPMENT, 
UPPER-LEVEL ANALYSIS INDICATES THE SYSTEM REMAINS SOUTH OF THE UPPER-
LEVEL SUBTROPICAL RIDGE AXIS UNDER THE INFLUENCE OF MODERATE TO 
STRONG (2O TO 30 KNOT) EASTERLY VERTICAL WIND SHEAR AND MAY STRUGGLE 
TO ESTABLISH A STRONG OUTFLOW MECHANISM.
3. FORECAST REASONING.
   A. THE SYSTEM HAS STRUGGLED TO STAY VERTICALLY STACKED AND IS NOW 
UNDER SIGNIFICANT SHEAR, EXPOSING THE LLCC. DUE TO THIS AS WELL AS 
CHANGES TO STATISTICAL-DYNAMICAL INTENSITY GUIDANCE, FORECAST 
INTENSITIES HAVE BEEN REDUCED FROM THE PREVIOUS WARNING.
   B. TS 05W IS FORECAST TO TRACK WEST-NORTHWESTWARD UNDER THE 
CONTINUED INFLUENCE OF THE SUBTROPICAL STEERING RIDGE THROUGHOUT THE 
FORECAST PERIOD. MINIMAL INTENSIFICATION MAY OCCUR AS THE SYSTEM 
TRACKS OVER FAVORABLE SST AND IMPROVING WESTWARD DIFFLUENCE ALOFT 
OFFSET THE NEGATIVE INFLUENCE OF PERSISTENT EASTERLY VERTICAL WIND 
SHEAR.
   C. THE MINIMAL INTENSIFICATION TREND WILL BE DISRUPTED AFTER TAU 
72 AS THE SYSTEM MOVES OVER LAND, ALTHOUGH VERTICAL WIND SHEAR IS 
EXPECTED TO RELAX SLIGHTLY AND POLEWARD OUTFLOW IMPROVE DURING THE 
SAME PERIOD AS A MIDLATITUDE SHORTWAVE TROUGH PASSES TO THE NORTH. 
EVEN THOUGH NUMERICAL MODEL TRACK GUIDANCE INDICATES A 170 NM SPREAD 
AT TAU 72, BUT IT REMAINS OVERALL IN GOOD AGREEMENT LENDING HIGH 
CONFIDENCE IN THE JTWC TRACK FORECAST WHICH IS POSITIONED CLOSE TO 
MULTI-MODEL CONSENSUS.//
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