WDPN32 PGTW 022100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 09W (SAOLA) WARNING NR 
041//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 21.7N 109.8E
   INITIAL INTENSITY: 40 KTS
   GEOGRAPHIC REFERENCE: 222 NM EAST-NORTHEAST OF HANOI, VIETNAM
   MOVEMENT PAST 6 HOURS: WEST-SOUTHWESTWARD AT 07 KTS
   SIGNIFICANT WAVE HEIGHT: XX FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A
FRAGMENTED AND DIFFICULT TO LOCALIZE CIRCULATION WITH FLARING
CONVECTION FAR REMOVED TO THE NORTH. A RECENT 021810Z ATMS 165GHZ
MICROWAVE IMAGE SHOWS A FAINT, OPEN CIRCULATION WITH NO DISCERNABLE
STRUCTURE. SURFACE OBSERVATION FROM THE LUCHOW PENINSULA AND BEIHAI
CHINA GIVE A GENERAL INDICATION THE LOW LEVEL CIRCULATION IS ABOUT
TO ENTER THE GULF OF TONKIN JUST EAST OF BEIHAI. THE INITIAL
POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED ON EIR, ATMS AND
SURFACE OBSERVATIONS. THE INITIAL INTENSITY OF 40 KTS IS ASSESSED
WITH LOW CONFIDENCE BASED ON THE TWO AVAILABLE DVORAK INTENSITY
ESTIMATES SHOWING A LARGE SPREAD, WHILE DPRINT INDICATES 36KTS.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: SOUTHEASTERN PERIPHERY OF A LOW TO
MID-LEVEL RIDGE OVER CENTRAL CHINA. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: NO CURRENT ESTIMATE
   RJTD: T3.5 - 55 KTS
   RCTP: T2.0 - 30 KTS

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 10-15 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: MODERATE POLEWARD

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: AS WE SPEAK, TS 09W (SAOLA) IS MOVING OVER THE
GULF OF TONKIN AS IT CONTINUES ITS GRADUAL SOUTHWESTERN TRACK UNDER
THE STEERING INFLUENCE OF THE LOW TO MID-LEVEL RIDGE OVER CENTRAL
CHINA. THOUGH THE OHC AND SST VALUES IN THE GULF OF TONKIN ARE
FAMOUSLY HIGH, DECREASING OUTFLOW ALOFT AND COPIOUS AMOUNTS OF DRY
AIR ENTRAINMENT WILL STIFLE ANY POTENTIAL INTENSIFICATION. AS THE
SYSTEM MOVES THROUGH THE GULF, IT WILL GRADUALLY WEAKEN, EVENTUALLY
REACHING 25KTS BY TAU 36. AFTER TAU 36, TRACK SPEED WILL SLOW TO A
CRAWL AND THE SYSTEM WILL BEING TO CURVE BACK TOWARD HAINAN BEFORE
EVENTUALLY DISSIPATING NEAR TAU 72.

MODEL DISCUSSION: NUMERICAL MODELS INDICATE GOOD TRACK AND
INTENSITY GUIDANCE WITH A BULK OF THE MEMBERS GENERALLY FOLLOWING
THE JTWC FORECAST. THERE ARE STILL SOME PESKY MEMBERS LIKE NVGM
THAT CONTINUE TRACKING THE SYSTEM TOWARD VIETNAM BUT THE MAJORITY
OF THE GUIDANCE IS IN SOLID AGREEMENT. FOR THESE REASONS THE JTWC
TRACK AND INTENSITY FORECASTS ARE BOTH PLACED WITH OVERALL MEDIUM
CONFIDENCE.

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