WDPN31 PGTW 190900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 10W (JONGDARI) WARNING 
NR 002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 26.3N 126.0E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 97 NM WEST OF KADENA AB
   MOVEMENT PAST 6 HOURS: NORTHWARD AT 12 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL
STORM 10W (JONGDARI) WITH A WELL-DEFINED, YET COMPLETELY EXPOSED
LOW-LEVEL CIRCULATION CENTER (LLCC) NOW DEVOID OF ANY DEEP
CONVECTION OVER THE CENTER. STRONG NORTH-NORTHEASTERLY SHEAR IS
EVIDENT AS THE RESIDUAL CONVECTION QUICKLY TRAILS OFF SOUTHWARD
FROM THE SYSTEM. ENVIRONMENTAL ANALYSIS INDICATES THAT 10W IS IN A
MARGINALLY UNFAVORABLE ENVIRONMENT FOR FURTHER DEVELOPMENT
CHARACTERIZED BY MODERATE EQUATORWARD OUTFLOW ALOFT, MODERATE TO
HIGH VERTICAL WIND SHEAR, AND WARM SEA SURFACE TEMPERATURES. THE
INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE
EXPOSED LLCC SEEN IN THE ANIMATED MSI. THE INITIAL INTENSITY OF 35
KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE SUBJECTIVE AND
OBJECTIVE INTENSITY ESTIMATES LISTED BELOW. ADDITIONALLY, A 190129Z
ASCAT-B IMAGE WHICH SHOWED A PATCH OF 35 KNOT WINDS IN THE EASTERN
SEMICIRCLE OF THE SYSTEM FURTHER SUPPORTS THE INITIAL INTENSITY.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: THE WESTERN PERIPHERY OF A DEEP-LAYER
STR CENTERED TO THE EAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   RJTD: T2.0 - 30 KTS
   RCTP: T1.5 - 25 KTS
   KNES: T1.5 - 25 KTS
   CIMSS SATCON: 32 KTS AT 190600Z
   CIMSS ADT: 29 KTS AT 190600Z
   CIMSS AIDT: 33 KTS AT 190600Z
   CIMSS DMINT: 33 KTS AT 190514Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY
UNFAVORABLE
   VWS: 20-25 KTS
   SST: 30-31 CELSIUS
   OUTFLOW: MODERATE EQUATORWARD

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: EXTENDED FORECAST TO 210600Z WITH
DISSIPATION OVER LAND VICE DISSIPATION OVER WATER.

FORECAST DISCUSSION: 10W IS FORECASTED TO CONTINUE TRACKING
NORTHWARD ALONG THE WESTERN PERIPHERY OF THE STR TO THE EAST
THROUGH TAU 36. AFTER TAU 36, 10W IS FORECAST TO TURN
NORTH-NORTHEASTWARD AS IT BEGINS TO ROUND THE STR, TOWARD SOUTH
KOREA. LANDFALL IS FORECAST TO OCCUR BETWEEN TAU 36 AND 48 IN
NORTHERN SOUTH KOREA. IN RESPONSE TO VERTICAL WIND SHEAR REMAINING
HIGH, DRY AIR BEGINNING TO ENTRAIN INTO THE SYSTEM, AND RELATIVELY
LOW OCEAN HEAT CONTENT VALUES, 10W IS FORECAST TO NOT INTENSIFY ANY
FURTHER. 35 KTS IS FORECAST TO SUSTAIN OVER THE NEXT 12 HOURS, WITH
A STEADY WEAKENING TREND THEREAFTER. AS 10W MAKES LANDFALL ALONG
THE COAST OF SOUTH KOREA, THE INTENSITY IS ANTICIPATED TO BE AROUND
20-25 KTS WITH DISSIPATION QUICKLY OCCURRING AFTER LANDFALL DUE TO
LAND INTERACTION AND INCREASED VERTICAL WIND SHEAR. 

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT
WITH A 180 NM CROSS-TRACK SPREAD AT TAU 48. NAVGEM MAKES UP THE
WESTERNMOST MEMBER, DEPICTING A STRAIGHT NORTHWARD TRACK THROUGH
THE FORECAST PERIOD. GFS DETERMINISTIC MAKES UP THE EASTERNMOST
MEMBER, DEPICTING A MORE NORTHEASTWARD TRACK AFTER TAU 24 AND MAKING
LANDFALL SOUTH OF KUNSAN. THE JTWC TRACK FORECAST IS PLACED CLOSER
TO THE LARGER GROUPING OF MEMBERS, AS WELL AS CONSENSUS, WITH
MEDIUM CONFIDENCE. INTENSITY GUIDANCE IS ALSO IN GOOD AGREEMENT
WITH ALL MEMBERS DEPICTING A WEAKENING TREND AFTER TAU 12. AS A
RESULT, THE JTWC INTENSITY FORECAST IS PLACED CLOSE TO CONSENSUS
WITH HIGH CONFIDENCE. 

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