WDXS31 PGTW 161500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 05S (BELAL) WARNING NR 
009//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 23.1S 59.8E
   INITIAL INTENSITY: 50 KTS
   GEOGRAPHIC REFERENCE: 295 NM EAST-SOUTHEAST OF ST DENIS
   MOVEMENT PAST 6 HOURS: EAST-SOUTHEASTWARD AT 08 KTS
   SIGNIFICANT WAVE HEIGHT: 25 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL
CYCLONE (TC) 05S (BELAL) CONTINUING TO TRACK TOWARDS THE SOUTHWEST.
ELEVATED MID- LEVEL WIND SHEAR (20-25KTS) HAS STEADILY DECOUPLED
THE STORM OVER THE LAST TWELVE HOURS REVEALING AN OPEN LOW LEVEL
CIRCULATION CENTER (LLCC) OFFSET TO THE NORTHWEST FROM THE
UPPER-LEVEL CONVECTION. OUTFLOW ALOFT PRIMARILY FLOWS SOUTHEAST
FROM THE DISLOCATED REGION OF UPPER-LEVEL CONVECTION. CLEAR REGIONS
TO THE WEST OF BELAL WRAP INTO THE STORM AS DRY AIR CONTINUES TO
ENGULF AND WEAKEN THE SYSTEM. SEA SURFACE TEMPERATURES (SST) UP TO
28C CONTINUE TO SUPPORT DEVELOPMENT. THE INITIAL POSITION IS PLACED
WITH HIGH CONFIDENCE WITH SUPPORT FROM A 161146Z SSMIS 37GHZ
SATELLITE MICROWAVE IMAGE THAT SHOWED A CLEAR-CUT MICROWAVE
EYE-LIKE FEATURE. THE INITIAL INTENSITY OF 50KTS IS PLACED WITH
MEDIUM CONFIDENCE BASED ON A BLEND OF AGENCY SUBJECTIVE AND
OBJECTIVE FIXES INCLUDING CIMSS AIDT ESTIMATE OF 48 KNOTS AND
161030Z SATCON ESTIMATE OF 51 KNOTS.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: SOUTHERN PERIPHERY OF THE NEAR
EQUATORIAL RIDGE (NER) TO THE NORTHWEST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   KNES: T3.5 - 55 KTS
   DEMS: T4.5 - 77 KTS
   FMEE: T4.0 - 65 KTS
   CIMSS ADT: 51 KTS AT 161030Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 20-25 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: WEAK POLEWARD

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: TRUNCATING THE FORECAST AT TAU 72 AS
THE STORM IS ANTICIPATED TO DISSIPATE.

FORECAST DISCUSSION: TC 05S (BELAL) IS FORECAST TO TRACK
EAST-SOUTHEAST THROUGH TAU 48 WHILE STEERED BY THE NER TO THE
NORTHWEST. THE SYSTEM SLOWS DOWN SIGNIFICANTLY BY TAU 36 AS IT RUNS
INTO A BUILDING RIDGE TO THE EAST WHICH EFFECTIVELY BLOCKS FURTHER
EASTWARD PROGRESSION. AFTER TAU 48, TC BELAL WILL VEER SHARPLY
SOUTHWEST AS THE NER TO THE NORTH WEAKENS AND THE STEERING
INFLUENCE SHIFTS TO THE LOW- TO MID-LEVEL MID-LATITUDE RIDGE TO THE
SOUTH. BELAL IS ANTICIPATED TO MAINTAIN 50 KNOT INTENSITY THROUGH
TAU 24 AS COMPETING ENVIRONMENTAL FACTORS OFFSET ONE ANOTHER. BY
TAU 24 HOWEVER, THE SYSTEM WILL EXPERIENCE A MORE RAPID WEAKENING
TREND, AS WIND SHEAR IS ANTICIPATED TO INCREASE TO APPROXIMATELY
30KTS BY TAU 48 AND INCREASE TO 55-60KTS BY TAU 96. A RADIOSONDE
SOUNDING FROM FMEE SHOWS THAT MOISTURE CEASES ABOVE 700MB, AND DRY
AIR IS EXPECTED TO CONTINUE TO ENTRAIN INTO THE SYSTEM AND WEAKEN
THE STORMS INTENSITY AS IT TRAVELS TO THE EAST SOUTH-EAST AND THEN
WEST SOUTH-WEST. THE COMBINATION OF THE DRY AIR ENTRAINMENT AND THE
MID LEVEL WIND SHEAR ARE ANTICIPATED TO OVERCOME THE FAVORABLE SST
OF 26C AND DISSIPATE THE STORM BY TAU 72.

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS GENERALLY IN GOOD
AGREEMENT THROUGH TAU 36, SHOWING A FAIRLY WELL-CONSTRAINED
CROSS-TRACK SPREAD OF JUST 50NM. HOWEVER, BY TAU 60 THE JTWC
CONSENSUS MEMBERS DEVIATE 180 DEGREES, WITH UKMET REPRESENTING THE
EAST BOUNDARY AND GFS ENSEMBLE ON THE WEST. BY TAU 72, NEARLY ALL
MEMBERS SHOW THE SYSTEM TURNING BACK TOWARDS THE SOUTHWEST BUT VARY
SHARPLY IN THE SPEED OF THE SOUTHWEST TRACK, LEADING TO A VERY WIDE
MODEL SPREAD OF 350NM. INTENSITY GUIDANCE AGREES ON A STEADY-STATE
FOR THE FIRST 24 HOURS, THEN ANTICIPATES A DECREASE STARTING AT TAU
24, DROPPING FROM 50KTS STEADILY TO 30KTS BY TAU 72, WHEN THE
SYSTEM ULTIMATELY DISSIPATES.

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