WDPN32 PGTW 030300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 09W (SAOLA) WARNING NR 
042//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 21.4N 109.4E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 197 NM EAST OF HANOI, VIETNAM
   MOVEMENT PAST 6 HOURS: SOUTHWESTWARD AT 05 KTS
   SIGNIFICANT WAVE HEIGHT: 9 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A WEAKLY
DEFINED AND PARTIALLY OBSCURED LLCC THAT JUST RECENT ENTERED THE
GULF OF TONKIN. AS POORLY DEFINED AS THE CIRCULATION IS, SURFACE
OBSERVATION HAVE BEEN THE PRIMARY LOCALIZATION TOOL. OBSERVATIONS
FROM BEIHAI AND ZHANJIANG CHINA INDICATE NORTHWESTERLY AND
SOUTHEASTERLY WINDS RESPECTIVELY, OTHERWISE CONFIRMING THAT THE
SYSTEM IS BETWEEN THE TWO SITES (OVER WATER). A 022242Z SSMIS 91GHZ
MICROWAVE IMAGE INDICATES THAT THE DEEP CONVECTION IS FAR REMOVED
TO THE NORTH OF THE LLCC. THE INITIAL POSITION IS PLACED WITH
MEDIUM CONFIDENCE BASED ON MSI AND SURFACE OBSERVATIONS. THE
INITIAL INTENSITY OF 35 KTS IS ASSESSED WITH LOW CONFIDENCE BASED
ON AUTOMATED INTENSITY ESTIMATES SUCH AS CIMSS ADT, AIDT AND
D-PRINT INDICATING 25-36KTS.

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
   CIMSS ADT: 25 KTS AT 030140Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 10-15 KTS
   SST: 29-30 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: TS 09W (SAOLA) RECENTLY ENTERED THE GULF OF
TONKIN AND IS FORECAST TO CONTINUE 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 24. AFTER TAU 24, TRACK SPEED WILL
SLOW TO A CRAWL AND THE SYSTEM WILL BEING TO CURVE BACK TOWARD
HAINAN BEFORE EVENTUALLY DISSIPATING NEAR TAU 48.

MODEL DISCUSSION: NUMERICAL MODELS ARE ONCE AGAIN SEPARATING INTO
TWO GROUPS, COAMPS-TC, NVGM, HAFS-A AND ECMWF CARRY THE SYSTEM
TOWARD VIETNAM UNTIL DISSIPATION WHILE THE REMAINING MODELS FOLLOW
THE JTWC FORECAST TRACK THROUGH DISSIPATION. FOR THIS REASON, THE
OVERALL TRACK FORECAST IS PLACED WITH LOW CONFIDENCE. WITH THE
EXCEPTION OF HAFS-A, RELIABLE MODEL INTENSITY GUIDANCE IS IN GOOD
AGREEMENT WITH ALL MEMBERS REGARDLESS OF TRACK, FOLLOWING THE JTWC
FORECAST TREND THROUGH DISSIPATION. HAFS-A IS IN GALAXY ON ITS OWN
AND INTENSIFIES THE SYSTEM OVER MAINLAND VIETNAM THROUGH TAU 96
BEFORE FINALLY DISSIPATING THE SYSTEM. THAT BEING SAID, THE JTWC
INTENSITY FORECAST IS PLACED WITH OVERALL MEDIUM CONFIDENCE. 

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