WDPN32 PGTW 020300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 10W (TEN) WARNING 
NR 002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 17.6N 113.1E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 289 NM SOUTH-SOUTHWEST OF HONG KONG
   MOVEMENT PAST 6 HOURS: WESTWARD AT 18 KTS
   SIGNIFICANT WAVE HEIGHT: 13 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A SMALL BUT
WELL-DEFINED, FULLY EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC).
DURING THE PREVIOUS WARNING CYCLE, DEEP CONVECTION HAD DEVELOPED IN
CLOSE PROXIMITY TO THE LLCC, COVERING IT BRIEFLY. HOWEVER, THE
PERSISTENT MODERATE NORTHERLY SHEAR HAS ONCE AGAIN BLOWN THE
CONVECTION OFF TO THE SOUTH, LEAVING BEHIND AN EXPOSED LLCC. THE
INITIAL POSITION IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE
EXPOSED LLCC IN THE MSI. THE INITIAL INTENSITY IS ASSESSED WITH
MEDIUM CONFIDENCE, BASED ON A BLEND OF THE OBJECTIVE AND SUBJECTIVE
INTENSITY ESTIMATES NOTED BELOW. ENVIRONMENTAL CONDITIONS ARE
MARGINAL, WITH WARM SSTS, AND GOOD OUTFLOW ALOFT OFFSET BY THE
PERSISTENT MODERATE NORTHERLY SHEAR AND DRY AIR ENTRENCHED ACROSS
THE NORTHERN HEMISPHERE OF THE CIRCULATION.

INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND
RADII).

CURRENT STEERING MECHANISM: SOUTHWESTERN PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) CENTERED SOUTHEAST OF KYUSHU. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   RJTD: T1.5 - 25 KTS
   KNES: T1.5 - 25 KTS
   CIMSS ADT: 31 KTS AT 020000Z
   CIMSS AIDT: 32 KTS AT 020000Z
   CIMSS D-PRINT: 23 KTS AT 020000Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 15-20 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE EQUATORWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   INITIAL INTENSITY: MEDIUM
   INITIAL WIND RADII: NOT APPLICABLE

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TROPICAL DEPRESSION (TD) 10W HAS SPED UP
SIGNIFICANTLY OVER THE PAST SIX HOURS, ALONG A STRENGTHENED
LOW-LEVEL STEERING GRADIENT. HOWEVER, THE SYSTEM IS FORECAST TO
SLOW DOWN OVER THE NEXT 12 TO 24 HOURS, ESPECIALLY AFTER TAU 12, AS
IT BEGINS TO TURN NORTHWARD AS THE STR PUSHES OFF TO THE EAST AND
WEAKENS THE STEERING GRADIENT. LANDFALL ALONG THE SOUTHEASTERN
COAST OF HAINAN ISLAND IS EXPECTED AROUND TAU 24. THE SYSTEM
QUICKLY CROSSES THE ISLAND AND EMERGES BACK OVER OPEN WATERS OF THE
GULF OF TONKIN BY TAU 36, CROSSES THE GULF AND MAKES ANOTHER
LANDFALL NEAR THE SINO-VIETNAMESE BORDER REGION SHORTLY AFTER TAU
48. THE SYSTEM THEN MOVES INLAND OVER SOUTHERN CHINA THROUGH THE
REMAINDER OF THE FORECAST PERIOD AS IT ROUND THE WESTERN FLANK OF
THE STR. IN TERMS OF INTENSITY, THE SYSTEM IS FORECAST TO INTENSIFY
SLIGHTLY OVER THE NEXT 12 HOURS, PARTICULARLY DURING THE OVERNIGHT
HOURS WHEN CONVECTIVE MAXIMUM WILL PROVIDE ANOTHER IMPULSE OF
ENERGY TO DEVELOP THE WIND FIELD. THE SYSTEM WILL WEAKEN TO 30
KNOTS AFTER INITIAL LANDFALL, THEN REINTENSIFY UP TO A PEAK OF 40
KNOTS AS IT MOVES OVER THE SHALLOW, WARM WATERS OF THE GULF OF
TONKIN, SHEAR DECREASES SLIGHTLY AND UPPER-LEVEL OUTFLOW IMPROVES.
AFTER THE SECOND LANDFALL, THE SYSTEM WILL RAPIDLY DETERIORATE OVER
LAND, ULTIMATELY DISSIPATING AS A TROPICAL CYCLONE OVER SOUTHERN
CHINA BY TAU 72. 

MODEL DISCUSSION: TRACK GUIDANCE IS IN GOOD AGREEMENT WITH THE
EXCEPTION OF GFS, WHICH DEPICTS THE SYSTEM TRAVERSING NORTHWARD AND
CURVING AROUND THE NORTHEASTERN TIP OF HAINAN. THE REMAINDER OF THE
GUIDANCE PACKAGE IS A 75-100NM WIDE ENVELOPE TRACING A GRADUALLY
RECURVING ARC THROUGH THE FORECAST PERIOD. THE JTWC FORECAST IS
PLACED ON THE WESTERN SIDE OF THE GUIDANCE ENVELOPE, CLOSEST TO THE
NAVGEM AND EXPERIMENTAL GDM FGNI TRACKER. INTENSITY GUIDANCE IS
MORE MIXED, WITH INCREASED UNCERTAINTY SINCE THE PREVIOUS RUN. THE
HWRF, HAFS-A AND COAMPS-TC PERSIST IN DEPICTING A PEAK INTENSITY
APPROACHING 50 KNOTS IN THE GULF OF TONKIN AND STEADY
INTENSIFICATION EVEN OVER HAINAN. THE SHIPS GUIDANCE MEANWHILE
APPEARS MORE REALISTIC IN THAT IT DEPICTS A MARGINAL
INTENSIFICATION IN THE SHORT-TERM, WEAKENING OVER HAINAN AND MODEST
REINTENSIFICATION OVER THE GULF OF TONKIN. THE JTWC FORECAST IS
PLACED CLOSE TO THE SHIPS-GFS MODEL TRACKER THROUGH THE FORECAST
PERIOD. 

FORECAST CONFIDENCE:
   TRACK 00-72 HR: MEDIUM
   INTENSITY 00-72 HR: MEDIUM//
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