WDPN32 PGTW 161500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 25W (MAN-YI) WARNING NR 
031//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 13.9N 124.5E
   INITIAL INTENSITY: 140 KTS
   GEOGRAPHIC REFERENCE: 208 NM EAST OF MANILA, PHILIPPINES
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 13 KTS
   SIGNIFICANT WAVE HEIGHT: 56 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY INDICATES THAT
SUPER TYPHOON (STY) 25W (MAN-YI) IS IN THE PROCESS OF MAKING
LANDFALL ON CATANDUANES ISLAND AS OF 1200Z. AT ANALYSIS TIME, THE
CENTER OF THE 17NM WIDE EYE REMAINED OFFSHORE, WITH THE
SOUTHWESTERN EYEWALL BRUSHING THE NORTHEASTERN COAST OF THE
ISLAND. SUBSEQUENT IMAGERY SHOWS THE CENTER MAKING A HARD WESTWARD
JOG, WITH THE EYE RAPIDLY DECREASING IN SIZE AND BECOMING
INCREASINGLY RAGGED AS IT MOVED OVER PANAY ISLAND AND THE TOWN OF
BAGAMANOC. EARLIER EIR IN THE LEAD UP TO THE 1200Z HOUR SHOWED THE
SYSTEM BECOMING LESS IMPRESSIVE, WITH EYE TEMPERATURES COOLING OVER
10C, WHILE CLOUD TOP TEMPERATURES WARMED ABOUT 3C, AND THE NORTHERN
PORTION OF THE EYEWALL APPEARED TO HAVE ERODED SOMEWHAT IN THE EIR
DEPICTION. A SERIES OF 91GHZ MICROWAVE PASSES UP TO 0948Z,
ESPECIALLY WHEN COMPARED TO EARLIER MICROWAVE IMAGERY FROM 12 HOURS
AGO, AND WHEN LOOPED TOGETHER IN THE MIMIC-TC PRODUCT, STRONGLY
SUGGESTS THE SYSTEM HAS COMPLETED A EYEWALL MELD TYPE EWRC JUST
PRIOR TO LANDFALL. THE INITIAL POSITION IS ASSESSED WITH HIGH
CONFIDENCE BASED ON THE 17NM WIDE EYE IN THE EIR. THE INITIAL
INTENSITY IS ASSESSED WITH MEDIUM CONFIDENCE. EVEN WHILE THE SYSTEM
QUALITATIVE LOOKS WORSE THAN IT DID SIX HOURS AGO, AND DVORAK
FINAL-T NUMBERS ARE STARTING FALL, THE WINDS WILL TAKE TIME TO SPIN
DOWN. HENCE THE INTENSITY IS HELD AT 140 KNOTS. THE ENVIRONMENT
REMAINS FAVORABLE IN THE AGGREGATE, THOUGH LAND INTERACTION, AND A
SLIGHT UPTICK IN MID-LEVEL SOUTHEASTERLY SHEAR ARE STARTING TO
OFFSET THE OTHERWISE FAVORABLE CONDITIONS.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: SOUTHWESTERN PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) CENTERED NEAR 20N 140E. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T7.0 - 140 KTS 
   RJTD: T7.0 - 140 KTS 
   RCTP: T7.5 - 155 KTS
   KNES: T6.5 - 127 KTS
   CIMSS SATCON: 140 KTS AT 161200Z
   CIMSS ADT: 132 KTS AT 161200Z
   CIMSS AIDT: 128 KTS AT 161200Z
   CIMSS D-MINT: 140 KTS AT 160942Z
   CIMSS D-PRINT: 137 KTS AT 161200Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: STRONG RADIAL
   OTHER FACTORS: LAND INTERACTION, EYEWALL REPLACEMENT CYCLE
(EWRC).

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: NOTWITHSTANDING THE RECENT SIGNIFICANT JOB
WESTWARD OVER CATANDUANES AND THE ACCOMPANYING SLOW DOWN, THE
OVERALL TRACK PHILOSOPHY HAS NOT CHANGED. THE SYSTEM SHOULD PUSH
OUT OVER WATER SHORTLY, AND WILL BE DRIVEN NORTHWESTWARD ALONG THE
SOUTHWESTERN SIDE OF THE STEERING RIDGE. A SECOND LANDFALL IS
EXPECTED TO OCCUR WITHIN THE NEXT 18 HOURS, WITH THE SYSTEM MOVING
INLAND BETWEEN DINGALAN AND BALER ON THE EAST COAST OF LUZON. THE
SYSTEM WILL THEN TRACK ALONG THE SOUTHERN EDGE OF THE CORDILLERA
CENTRAL MOUNTAIN RANGE, AND PUSH BACK OVER WATER VIA THE LINGAYEN
GULF BY TAU 24. THE SYSTEM WILL CONTINUE TO TRACK NORTHWESTWARD
UNTIL ABOUT TAU 36, WHEN IT WILL START TO MEET THE LEADING EDGE OF
STRONG NORTHEASTERLY FLOW STREAMING SOUTH OUT OF THE TAIWAN STRAIT,
ASSOCIATED WITH A STRONG COLD SURGE EVENT. THE SYSTEM SLOWS SHARPLY
AFTER TAU 36 AND BEGINS TO TURN MORE WESTWARD AS IT INTERACTS WITH
THE SURGE FLOW. IN THE NEXT 12 HOURS OF THE FORECAST, THE FORECAST
CALLS FOR ABOUT 15 KNOTS OF WEAKENING, THOUGH IF THE CURRENT TREND
HOLDS AND THE SYSTEM STALLS FOR LONGER THAN ANTICIPATED OVER
CATANDUANES, THE AMOUNT OF WEAKENING COULD BE MUCH MORE. ONCE THE
SYSTEM GETS AWAY FROM CATANDUANES HOWEVER, OVERALL ENVIRONMENTAL
CONDITIONS WILL REMAINS FAVORABLE AND IT WILL BE ABLE TO MAINTAIN
INTENSITY TO A BETTER DEGREE AND THE SYSTEM WILL BE A SIGNIFICANT
TYPHOON WHEN IT MAKES ITS SECOND LANDFALL. CROSSING LUZON WILL
WREAK HAVOC ON THE SYSTEM AND IT WILL WEAKEN TO JUST 80 KNOTS OR
LESS WHEN IT MOVES BACK INTO THE LINGAYEN GULF. ONCE IN THE SOUTH
CHINA SEA, STEADILY INCREASING SHEAR WILL FURTHER WEAKEN THE SYSTEM
AS IT MOVES SOUTH OF HONG KONG. JUST AFTER TAU 48, SOUTHWESTERLY
SHEAR WILL INCREASE TO 30 KNOTS OR MORE, USHERING IN AN INFLUX OF
VERY DIR MID-LEVEL AIR. THE COMBINATION OF SHEAR AND DRY AIR WILL
SMOTHER THE VORTEX, AND LEAD TO RAPID WEAKENING AFTER TAU 72. THE
SYSTEM WILL TURN SOUTHWESTWARD ALONG THE LOW-LEVEL NORTHEASTERLY
FLOW WHILE CONTINUING TO WEAKEN. THE SYSTEM WILL DISSIPATE AS IT
MAKES A THIRD LANDFALL NEAR DA NANG, VIETNAM BY TAU 120.

MODEL DISCUSSION: DETERMINISTIC TRACK GUIDANCE REMAINS IN VERY
TIGHT AGREEMENT THROUGH TAU 48, WITH LITTLE IN THE WAY OF CROSS- OR
ALONG-TRACK SPREAD IN THE CONSENSUS MEMBERS. HOWEVER, NONE OF THE
GUIDANCE IS TAKING INTO ACCOUNT THE RECENT SLOW-DOWN AND WOBBLE
OVER CATANDUANES, AND THE IMPACT OF THAT ON THE LONGER-TERM
FORECAST TRACK IS UNKNOWN AT THIS TIME BUT COULD LEAD TO CHANGE IN
BOTH THE TIMING AND LOCATION OF THE SECOND LANDFALL. AFTER TAU 48,
THE MODELS BEGIN TO DIVERGE ON BOTH THE TIMING AND STRENGTH OF THE
TURN SOUTHWARD, WITH THE ECMWF BEING THE SLOWEST WHILE THE GFS IS
THE FASTEST. THESE TRENDS CONTINUE THROUGH TAU 120, RESULTING IN A
515NM ALONG-TRACK SPREAD BETWEEN THE GFS AND ECMWF AT TAU 120. THE
JTWC FORECAST LIES CLOSE TO THE CONSENSUS MEAN IN TERMS OF TRACK
AND SPEED, THROUGH THE ENTIRE FORECAST. INTENSITY GUIDANCE IS IN
GOOD AGREEMENT THROUGH THE FORECAST PERIOD. HOWEVER, AS WITH THE
TRACK GUIDANCE, IT IS NOT TAKING INTO ACCOUNT THE IMPACT OF THE JOG
AND STAGNATION OVER CATANDUANES ISLAND. THE JTWC FORECAST CLOSELY
FOLLOWS THE HAFS-A TREND THROUGH THE FORECAST PERIOD. 

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