WDPN31 PGTW 050300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 26W (BOPHA) WARNING NR 38//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON 26W (BOPHA) LOCATED APPROXIMATELY 200 NM NORTHWEST OF 
ZAMBOANGA, PHILIPPINES HAS TRACKED WEST-NORTHWESTWARD AT 12 KNOTS 
OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY
(MSI) SHOWS NEWLY FORMING OVERSHOOTING TOPS OVER THE LOW-LEVEL
CIRCULATION CENTER (LLCC) AS THE SYSTEM NEARS NORTHERN PALAWAN. THE
CURRENT POSITION IS BASED ON THE MSI IMAGERY AND SIMILAR CENTER FIX
POSITIONS FROM PGTW AND RJTD WITH FAIR CONFIDENCE. THE CURRENT
INTENSITY IS BASED ON AGREEABLE DVORAK ESTIMATES OF 77 KNOTS FROM ALL
REPORTING AGENCIES AS WELL AS CONGRUENT OBJECTIVE INTENSITY
ESTIMATES. UPPER-LEVEL ANALYSIS INDICATES TY 26W IS LOCATED A FEW
DEGREES SOUTHEAST OF A COL REGION BETWEEN THE SUBTROPICAL RIDGES
CENTERED TO THE EAST AND WEST. POLEWARD OUTFLOW, ENHANCED BY A
CONNECTION INTO THE MID-LATITUDE WESTERLIES, IS PROVIDING THE MAIN
EXHAUST MECHANISM FOR TY 26W AS EQUATORWARD OUTFLOW IS NO LONGER
CROSS EQUATORIAL. VERTICAL WIND SHEAR (VWS) REMAINS WEAK AT 10 TO 15
KNOTS. TY 26W IS CURRENTLY STEERING ALONG THE SOUTHWEST PERIPHERY OF
THE EASTERN LOBE OF THE SUBTROPICAL RIDGE (STR) AND STEERING TOWARDS
THE COL REGION.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
   B. TY 26W IS FORECAST TO CONTINUE TRACKING GENERALLY
WEST-NORTHWESTWARD ALONG THE SOUTHWESTERN PERIPHERY OF THE EASTERN
STR TOWARDS THE COL. SLIGHT INTENSIFICATION TO A PEAK OF 90 KNOTS IS
EXPECTED TO OCCUR BY TAU 36 AND INTO TAU 48 DUE TO FAVORABLE SEA
SURFACE TEMPERATURES AND OUTFLOW. BY TAU 72 A WEAKENING TREND SHOULD
COMMENCE AS OCEAN HEAT CONTENT DECREASES AND VWS INCREASES AND A
NORTHEAST MONSOON SURGE BEGINS TO PUSH INTO THE SOUTH CHINA SEA.
   C. DURING DAYS FOUR AND FIVE TY 26W WILL ENCOUNTER A STRONG
NORTHEAST MONSOON SURGE AND ENTER A VERY WEAK STEERING ENVIRONMENT
UNDERNEATH THE COL REGION. THE SYSTEM IS EXPECTED TO TRACK SLOW AND
PERHAPS ERRATIC WITH A LOOPING MOTION NOT OUT OF THE QUESTION.
HOWEVER, DUE TO THE COMPLEXITIES OF FORECASTING SUCH A MOTION WITH
VALIDITY THE FORECAST PHILOSOPHY IS TO KEEP THE TRACK SPEEDS SLOW AND
GENERALLY WEST TO EVEN SOUTHWEST AS THE SYSTEM INGESTS DRY AIR IN THE
MID-LEVELS AND VWS INCREASES, PERHAPS BEGINNING TO DECOUPLE THE DEEP
CONVECTION FROM THE LLCC. OBJECTIVE AID GUIDANCE HAS NOT CHANGED MUCH
IN THE PAST 12 HOURS AS THERE CONTINUES TO BE LARGE SPREAD IN THE
CONSENSUS MEMBERS. THIS LATEST RUN HOWEVER DOES SHOW MORE TRACKERS
INDICATING A CLOCKWISE LOOP BUT THE DEGREE OF TURN VARIES GREATLY.
JGSM CONTINUES TO PORTRAY A WESTWARD TRACK. ALL IN ALL THE LOOPING
TRACKERS JUST CONFIRMS THE WEAK STEERING ENVIRONMENT AND THIS IS WHY
THE OFFICIAL JTWC TRACK FORECAST REMAINS CONSISTENT WITH THE PREVIOUS
FORECAST WITH SLOW TRACK SPEEDS INDICATING QUASI-STATIONARY MOVEMENT
IN THE EXTENDED FORECAST WITH A GRADUAL WEAKENING TREND. DUE TO THE
LARGE SPREAD IN TRACKERS, LOW TRACK CONFIDENCE REMAINS.//
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