WDPN31 PGTW 071500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 05W (PEIPAH) 
WARNING NR 19//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION (TD) 05W (PEIPAH), LOCATED APPROXIMATELY 804 
NM SOUTHEAST OF MANILA, PHILIPPINES, HAS TRACKED WEST-SOUTHWESTWARD 
AT 04 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED 
(EIR) SATELLITE IMAGERY DEPICTS INCREASED DEEP CONVECTION OBSCURING 
THE LOW-LEVEL CIRCULATION CENTER (LLCC). A 070849Z SSMIS MICROWAVE 
IMAGE REVEALS BROKEN CONVECTIVE BANDING OVER THE NORTHERN AND 
WESTERN PERIPHERIES WRAPPING INTO THE LLCC. THE CURRENT POSITION IS 
BASED ON THE EIR ANIMATION AND SSMIS IMAGE WITH FAIR CONFIDENCE. THE 
CURRENT INTENSITY OF 25 KNOTS IS BASED ON AN ASSESSMENT OF DVORAK 
INTENSITY ESTIMATES FROM PGTW AND RJTD AS WELL AS THE STRUCTURE ON 
THE MICROWAVE IMAGE. ALTHOUGH WARM SEA SURFACE TEMPERATURES ARE 
FAVORABLE FOR DEVELOPMENT, UPPER-LEVEL ANALYSIS INDICATES THE SYSTEM 
REMAINS SOUTH OF THE SUBTROPICAL RIDGE (STR) AXIS UNDER THE 
INFLUENCE OF MODERATE TO STRONG (2O TO 30 KNOT) EASTERLY VERTICAL 
WIND SHEAR (VWS) AND MAY STRUGGLE TO ESTABLISH A STRONG OUTFLOW 
MECHANISM. ADDITIONALLY, THE SLOW MOVEMENT OVER THE PAST SIX HOURS 
INDICATES THE SYSTEM HAS ENTERED A WEAK STEERING ENVIRONMENT OF A 
WEAKENING EXTENSION OF A STR TO THE NORTH.
3. FORECAST REASONING.
   A. THE INTENSITY FORECAST REMAINS CHALLENGING DUE TO THE MODERATE 
TO STRONG VWS, WHICH IS HINDERING ORGANIZATION. HOWEVER, UPPER-LEVEL 
CONDITIONS ARE EXPECTED TO IMPROVE AS A MIDLATITUDE TROUGH 
APPROACHES PROVIDING GOOD POLEWARD OUTFLOW FOR A MODERATE 
INTENSIFICATION. DUE TO THIS AS WELL AS CHANGES TO STATISTICAL-
DYNAMICAL INTENSITY GUIDANCE, FORECAST INTENSITIES HAVE BEEN 
INCREASED FROM THE PREVIOUS WARNING.
   B. TD 05W IS FORECAST TO REMAIN IN THE WEAK STEERING ENVIRONMENT 
CAUSING SLOW TRACK SPEEDS IN THE NEAR TERM. BY TAU 36, A MIDLATITUDE 
TROUGH WILL DIG INTO THE EAST CHINA SEA, ALLOWING THE SYSTEM TO TURN 
NORTHWESTWARD. TD 05W IS EXPECTED TO MAINTAIN INTENSITY IN THE NEAR 
TERM, BUT MAY INTENSIFY SLIGHTLY AROUND TAU 72 DUE TO A MINIMAL 
RELAXATION OF VERTICAL WIND SHEAR AND IMPROVED POLEWARD OUTFLOW 
INDUCED BY AFOREMENTIONED MIDLATITUDE TROUGH PASSING TO THE NORTH.
   C. TD 05W IS EXPECTED TO CONTINUE NORTHWESTWARD INTO NORTHERN 
MINDANAO THROUGH THE REMAINDER OF THE FORECAST PERIOD. DYNAMIC MODEL 
GUIDANCE IS OVERALL IN AGREEMENT, INDICATING A POLEWARD SHIFT; 
HOWEVER, A LARGE SPREAD AMONG AVAILABLE TRACKERS STILL EXISTS, 
LEADING TO LOW CONFIDENCE IN THE JTWC TRACK FORECAST WHICH IS 
POSITIONED CLOSE TO MULTI-MODEL CONSENSUS.//
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