WDPN33 PGTW 131500
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 19W (PARMA)//
WARNING NR 64// 
RMKS/
1. FOR METEOROLOGISTS. 
2. 12 HOUR SUMMARY AND ANALYSIS. 
    A. OVER THE PAST 12 HOURS PARMA HAS CONTINUED TO SLOWLY DRIFT TO
THE WEST-NORTHWEST UNDER THE INFLUENCE OF THE SUBTROPICAL RIDGE (STR)
TO THE NORTH OF PARMA. CONVECTION REMAINS DEEPEST IN A SINGLE BAND,
WRAPPING COMPLETELY AROUND THE LOW LEVEL CIRCULATION CENTER (LLCC).
THE LLCC HAS REMAINED FREE OF CONVECTION OVER THE PAST 12 HOURS, WITH
A RECENT DECREASE IN DEEP CONVECTION ON THE WESTERN PERIPHERY OF THE
BAND, LIKELY DUE TO INCREASED LAND INTERACTION AFFECTING THE LOW
LEVEL INFLOW. CURRENT INTENSITY IS BASED ON DVORAK ESTIMATES OF 35
KNOTS FROM PGTW AND RJTD.
3. FORECAST REASONING.
    A. THE CURRENT FORECAST DEVIATES FROM THE PREVIOUS FORECAST IN
REGARDS TO TRACK, WITH THE CURRENT FORECAST TAKING PARMA FURTHER
NORTH. THIS IS BASED PREDOMINANTLY ON PERSISTENCE AS MODEL GUIDANCE
HAS CONTINUED TO SHOW A SOUTHERN TURN WHILE PARMA HAS CONTINUED TO
TRACK WEST-NORTHWESTWARD. BASED ON THIS THE FORECAST HAS BEEN SHIFTED
TO THE NORTH OF THE MODEL CONSENSUS. 
    B. PARMA WILL CONTINUE TO TRACK WEST-NORTHWESTWARD UNDER THE
INFLUENCE OF THE STR, UNTIL IT MAKES LANDFALL IN VIETNAM. AS PARMA
TRACKS INLAND, THE TRACK WILL FLATTEN IN A MORE WESTWARD DIRECTION,
AND IS EXPECTED TO DISSIPATE QUICKLY OVER VIETNAM. MODEL GUIDANCE,
AS MENTIONED IN PARA 3.A., HAS NOT SHOWN SKILL IN FORECASTING THIS 
SYSTEM OVER THE PAST 12 TO 24 HOURS. BASED ON THIS FACT, THE CURRENT
FORECAST RELIES HEAVILY ON THE PERSISTENT TRACK OF PARMA VICE THE
CONSENSUS OF MODEL GUIDANCE. IN GENERAL, THIS IS DUE TO THE POOR
REPRESENTATION OF PARMA IN MODEL FIELDS AS IT WEAKENS.//
NNNN