WDPN32 PGTW 250300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 10W (FRANCISCO) WARNING 
NR 012//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 26.7N 123.7E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 153 NM NORTHEAST OF TAIPEI, TAIWAN
   MOVEMENT PAST 6 HOURS: WESTWARD AT 11 KTS
   SIGNIFICANT WAVE HEIGHT: 16 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A COMPACT,
WELL-DEFINED AND FULLY EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC),
WITH ISOLATED POCKETS OF SHALLOW CONVECTION ALONG THE WESTERN
SPIRAL BANDS. MID-LEVEL DRY AIR IS PARTICULARLY EVIDENT ACROSS THE
EASTERN TWO THIRDS OF THE ROTATION, WHERE THERE IS LIMITED TO NO
CONVECTIVE ACTIVITY. THERE HAS NOT BEEN A SCATTEROMETER PASS FOR
THE PAST 12 HOURS, BUT A FEW SHIP OBSERVATIONS OFF THE COAST OF
CHINA AND NORTHERN TAIWAN REPORT WINDS AROUND 30 KNOTS FROM THE
NORTH-NORTHEAST, PROVIDING GOOD SUPPORT TO THE INITIAL INTENSITY.
HOWEVER, THE GALE-FORCE WINDS ARE VERY LIKELY DECREASING IN AREAL
COVERAGE AS THE SYSTEM SLOWLY WEAKENS AS IT MOVES CLOSER TO THE
CENTER OF THE LARGER CYCLONIC ROTATION. THE INITIAL POSITION IS
ASSESSED WITH HIGH CONFIDENCE BASED ON THE EXPOSED LLCC. THE
INITIAL INTENSITY IS ASSESSED WITH HIGH CONFIDENCE AS WELL, BASED
ON PERSISTENCE WITH EARLIER MEASUREMENTS AND THE OBJECTIVE
ESTIMATES NOTED BELOW. ENVIRONMENTAL CONDITIONS ARE UNFAVORABLE,
WITH LOW TO MODERATE WIND SHEAR, MARGINAL SSTS, WEAK OUTFLOW AND
VERY DRY MID-LEVEL AIR OVERLAYING THE BULK OF THE VORTEX.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: SYSTEM IS EMBEDDED WITHIN THE NORTHERN
PERIPHERY OF A LARGE CYCLONIC ROTATION EXTENDING FROM OKINAWA IN
THE NORTH TO LUZON IN THE SOUTH, ROUGHLY CENTERED ON TAIWAN. A
DEEP-LAYER SUBTROPICAL RIDGE IS POSITIONED OVER NORTH KOREA.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T1.5 - 25 KTS
   RJTD: T2.0 - 30 KTS
   RCTP: T2.0 - 30 KTS
   KNES: T2.0 - 30 KTS
   CIMSS ADT: 33 KTS AT 250030Z
   CIMSS AIDT: 35 KTS AT 250030Z
   CIMSS D-PRINT: 29 KTS AT 250030Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 10-15 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: WEAK POLEWARD
   OTHER FACTORS: MID-LEVEL DRY AIR OVERLAYING THE LOW-LEVEL
CIRCULATION. 

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TS 10W HAS TRACKED DUE WEST OVER THE PAST FEW
HOURS BUT CONTINUES TO SLOW DOWN AS IT MOVES INTO AN AREA OF
GENERALLY WEAKER STEERING FLOW, MOVING CLOSER TO THE CENTER OF THE
LARGE CYCLONIC CIRCULATION. OVER THE NEXT 12 HOURS, TS 10W WILL
BEGIN TO MAKE A SHARP TURN BACK TO THE SOUTHEAST AS IT REACHES THE
WESTERN EDGE OF THE LARGER CIRCULATION AND IS PULLED BACK EASTWARD
TOWARDS TS 11W MOVING UP FROM THE SOUTH. BINARY INTERACTION IS
EXPECTED TO BE WEAK, WITH NEITHER TS 10W NOR TS 11W BEING STRONG
ENOUGH TO CAPTURE THE OTHER. THE LARGER FACTOR PULLING TS 10W
EASTWARD WILL BE THE REORIENTATION OF THE LARGE CYCLONIC
CIRCULATION INTO A REVERSE ORIENTED MONSOON TROF, GENERALLY
CHARACTERIZED BY A HIGH-LATITUDE, EAST-WEST ORIENTED TROF PATTERN.
AT THE SAME TIME THE SYSTEM IS MAKING ITS TURN, IT WILL CONTINUE TO
STEADILY WEAKEN, SUCH THAT BY THE TAU 36, IT WILL HAVE DISSIPATED
AS A TROPICAL CYCLONE AND MERGED INTO THE LARGER ROTATION. 

MODEL DISCUSSION: THE BULK OF THE DETERMINISTIC TRACK GUIDANCE IS
BEING DRIVEN BY PERSISTENCE AS THE MODELS ARE STRUGGLING TO
MAINTAIN A LOCK ON THE VORTEX. PERSISTENCE IN THIS CASE RESULTS IN
A TRACK STRAIGHT INTO THE CHINESE COAST, WHICH IS AN UNLIKELY
SCENARIO. THE ONE MODEL THAT SHOWS A TURN TO THE EAST IS THE GFS,
AND THE JTWC FORECAST DEVIATES FROM THE PACK AND FOLLOWS THE GFS
AFTER TAU 12. INTENSITY GUIDANCE HOWEVER IS IN GOOD AGREEMENT THAT
THE SYSTEM WILL STEADILY WEAKEN BELOW WARNING CRITERIA WITHIN THE
NEXT 24 TO 36 HOURS.  

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