WDPN32 PGTW 171500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 25W (MAN-YI) WARNING NR 035//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 16.6N 120.7E
   INITIAL INTENSITY: 90 KTS
   GEOGRAPHIC REFERENCE: 121 NM NORTH OF MANILA, PHILIPPINES
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 14 KTS
   SIGNIFICANT WAVE HEIGHT: XX FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TYPHOON (TY) 25W (MAN-YI) MADE LANDFALL IN THE NORTHERN PORTION OF
BALER BAY, NEAR DIPACULAO, AROUND 170700Z AS A 130 KNOT SUPER
TYPHOON. SINCE THAT TIME, THE SYSTEM HAS MOVED RAPIDLY INLAND AND
BY ANALYSIS TIME WAS ESTIMATED TO BE LOCATED JUST NORTH OF BAQUIO,
MOVING NORTHWESTWARD AT 13 KNOTS. A 170948Z WSF-M 37GHZ MICROWAVE
IMAGE REVEALED THAT THE LOW-LEVEL STRUCTURE REMAINS FAIRLY
WELL-DEFINED, WITH SPIRAL BANDS OF DEEP CONVECTION WRAPPING INTO A
DEFINED LOW-LEVEL CIRCULATION CENTER (LLCC). EXTRAPOLATION OF THIS
FEATURE, ALONG WITH ANALYSIS OF THE ANIMATED ENHANCED INFRARED
(EIR) SATELLITE IMAGERY PROVIDED MEDIUM CONFIDENCE TO THE INITIAL
POSITION. THE INITIAL INTENSITY IS ASSESSED WITH LOW CONFIDENCE DUE
TO A LACK OF AVAILABLE OVERLAND INTENSITY ESTIMATES. THE CIMSS
DPRINT AND DMINT ARE ESTIMATING WINDS ABOVE 100 KNOTS WHICH IS
ASSESSED AS BEING CONSIDERABLY TOO HIGH. THUS, THE INTENSITY IS
ESTIMATED USING AN EMPIRICAL OVERLAND DECAY MODEL. NOW THAT THE
SYSTEM IS INLAND OVER ROUGH TERRAIN, THE ENVIRONMENT IS MARGINAL AT
BEST, CUT-OFF FROM A HEAT SOURCE AND EXPERIENCING INCREASED
FRICTIONAL EFFECTS, THE OTHERWISE FAVORABLE OUTFLOW AND SHEAR
CONDITIONS ARE NOT ENOUGH TO OFFSET THE NEGATIVE INFLUENCES.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: SOUTHWESTERN PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) CENTERED NEAR 20N 135E. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: NO CURRENT ESTIMATE
   RJTD: T6.0 - 115 KTS
   DEMS: T6.5 - 127 KTS
   CIMSS D-MINT: 113 KTS AT 170930Z
   CIMSS D-PRINT: 109 KTS AT 171200Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 10-15 KTS
   SST: OVER LAND
   OUTFLOW: MODERATE RADIAL
   OTHER FACTORS: TERRAIN INTERACTION.

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   INITIAL INTENSITY: LOW
   INITIAL WIND RADII: LOW

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: TY 25W WILL MOVE BACK OVER WATER IMMINENTLY
AND CONTINUE MOVING NORTHWESTWARD ALONG THE SOUTHWESTERN SIDE OF
THE STEERING RIDGE THROUGH TAU 12. THERE IS CURRENTLY A SMALL BREAK
IN THE RIDGE NEAR TAIWAN BUT GLOBAL MODEL FIELDS SHOW THIS BREAK
QUICKLY CLOSING, REPLACED BY ENHANCED RIDGING WHICH WILL EXTEND
FROM NORTHERN VIETNAM, THROUGH TAIWAN AND INTO THE WESTERN PACIFIC.
THIS BUILDING RIDGE WILL INHIBIT FURTHER POLEWARD MOVEMENT AFTER
TAU 12, AND THE SYSTEM WILL QUICKLY TURN WESTWARD BY TAU 24,
CONTINUING ON THIS COURSE THROUGH TAU 36. IN TERMS OF INTENSITY,
THE SYSTEM WILL CONTINUE TO WEAKEN AS IT PASSES OVER THE LAST BIT
OF LAND IN THE NEXT COUPLE OF HOURS. THE SYSTEM WILL CONTINUE
WEAKENING AS IT MOVES BACK OVER WATER AS THE VORTEX WILL TAKE TIME
TO RECOVER, WHILE SHEAR SLOWLY PICKS UP THE FURTHER WEST THE SYSTEM
TRACKS. BY TAU 24, SHEAR STARTS TO INCREASE SHARPLY, AND DRY
MID-LEVEL AIR BEGINS TO MOVE IN FROM THE SOUTHWEST. BY TAU 36, THE
SYSTEM WILL BE OVERWHELMED BY HIGH SOUTHWESTERLY SHEAR AND
COMPLETELY SMOTHERED BY MID-LEVEL DRY AIR. THE REMNANT VORTEX WILL
THEN TURN SOUTHWESTWARD AND STEADILY WEAKEN THROUGH THE REMAINDER
OF THE FORECAST PERIOD, DISSIPATING TO THE SOUTH OF HAINAN, NO
LATER THAN TAU 96 AND POTENTIALLY AS EARLY AS TAU 72.

MODEL DISCUSSION: TRACK GUIDANCE IN IN FAIRLY GOOD AGREEMENT
THROUGH TAU 36, WITH A CROSS-TRACK SPREAD OF JUST 70NM. HOWEVER,
EVEN AS EARLY AS THIS POINT, THE GFS AND GEFS BEGIN TO RACE AHEAD
OFF THE OTHER CONSENSUS MEMBERS, AS IT DEPICTS A MUCH STRONGER
RIDGE TO THE NORTH AND AN ENHANCED STEERING GRADIENT. THE REMAINDER
OF THE GUIDANCE STARTS TO HANG BACK AND REMAINS CONSISTENT WITH THE
CONSENSUS MEAN. BY TAU 48, THE MODELS BEGIN TO SHARPLY DIVERGE AS
THEY HANDLE THE REMNANT VORTEX DIFFERENTLY. THE GFS TAKES THE
SYSTEM OVER HAINAN AND INTO THE GULF OF TONKIN, THE ECMWF LOSES THE
VORTEX OFF THE EAST COAST OF HAINAN AND THE GEFS TAKES THE SYSTEM
INTO VIETNAM NORTH OF HUE. THE JTWC FORECAST REMAINS CONSISTENT
WITH THE PREVIOUS FORECASTS, DISSIPATING THE SYSTEM JUST EAST OF
THE CENTRAL VIETNAM COASTLINE BY TAU 96, CLOSE TO THE CONSENSUS
MEAN. INTENSITY GUIDANCE IS IN STRONG AGREEMENT ON THE TREND AND
PACE OF WEAKENING THROUGH THE FORECAST PERIOD, THROUGH SOME
GUIDANCE INDICATES DISSIPATION AS EARLY AS TAU 72. 

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: MEDIUM
   TRACK 72-120 HR: LOW
   INTENSITY 0 - 72 HR: MEDIUM
   INTENSITY 72-120 HR: LOW//
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