Advisories

WDXS31 PGTW 230900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 02S (AGUEDA) WARNING 
NR 007//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 5.7S 49.5E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 612 NM EAST OF DAR ES SALAAM, TANZANIA
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 04 KTS
   SIGNIFICANT WAVE HEIGHT: 14 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS THAT OVER 
THE PAST 6-12 HOURS, TC 02S HAS UNDERGONE TWO DISTINCT CONVECTIVE
PULSES, CHARACTERIZED BY FLARING DEEP CONVECTION OBSCURING THE 
LOW-LEVEL CIRCULATION CENTER (LLCC), FOLLOWED BY RAPID COLLAPSE 
THAT TEMPORARILY EXPOSED THE LLCC BEFORE REBUILDING OVER THE CENTER 
WITHIN THE PAST FEW HOURS. THE ANIMATED MSI ALSO REVEALS A SHARP, 
WELL-DEFINED WESTERN CONVECTIVE BOUNDARY, INDICATIVE OF MODERATE 
MID-LEVEL WESTERLY WIND SHEAR IMPINGING ON THE SYSTEM. A 230227Z 
RCM-3 SAR PASS INDICATED A COMPACT LLCC SUPPORTED BY SURFACE WINDS 
OF 30-35 KTS PRIOR TO THE RECENT CONVECTIVE REDEVELOPMENT. THE 
INITIAL POSITION IS ASSESSED WITH MEDIUM CONFIDENCE, BASED ON AN 
EXTRAPOLATION OF THE SAR-DERIVED FIX. THE INITIAL INTENSITY IS 
ASSESSED WITH HIGH CONFIDENCE, BASED ON A CONFLUENCE OF AGENCY 
DVORAK FIXES, OBJECTIVE INTENSITY ESTIMATES, AND THE RECENT SAR 
DATA. ENVIRONMENTAL CONDITIONS ARE  UNFAVORABLE, CHARACTERIZED BY 
MODERATE WESTERLY MID-LEVEL SHEAR, MID-LEVEL DRY AIR ENTRAINMENT, 
WEAK UPPER-LEVEL OUTFLOW, AND MARGINAL SEA SURFACE TEMPERATURES 
(SSTS).

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: FAR NORTHWESTERN PERIPHERY OF A LOW- TO
MID-LEVEL SUBTROPICAL RIDGE (STR) CENTERED FAR TO THE SOUTHEAST. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   DEMS: T2.5 - 35 KTS
   CIMSS ADT: 34 KTS AT 230530Z
   CIMSS AIDT: 34 KTS AT 230530Z
   CIMSS D-MINT: 27 KTS AT 230503Z
   CIMSS D-PRINT: 27 KTS AT 230530Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 5-10 KTS
   SST: 26-27 CELSIUS
   OUTFLOW: WEAK POLEWARD
   OTHER FACTORS: ELEVATED MID-LEVEL SHEAR, AND DRY AIR. 

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THE FORECAST HAS BEEN TRUNCATED TO 24
HOURS. 

FORECAST DISCUSSION: TC 02S WILL TRACK WESTWARD ALONG THE NORTHERN
PERIPHERY OF AN EXTENSIVE STR EXTENDING FROM SOUTHERN MOZAMBIQUE, 
ACROSS MADAGASCAR, AND FAR INTO THE SOUTHERN INDIAN OCEAN. REGARDING 
INTENSITY, THE CURRENT CONVECTIVE BURST IS LIKELY THE FINAL PULSE, 
AS INCREASING MID-LEVEL WESTERLY SHEAR AND ROBUST DRY AIR INTRUSION 
WILL VERTICALLY DECOUPLE THE SYSTEM. THE SHALLOW REMNANT VORTEX WILL
CONTINUE TRACKING WESTWARD INTO AN INCREASINGLY HOSTILE ENVIRONMENT,
RESULTING IN DISSIPATION BELOW THE 35-KT WARNING THRESHOLD WITHIN 
THE NEXT 24 HOURS. 

MODEL DISCUSSION: TRACK GUIDANCE IS IN TIGHT AGREEMENT; THEREFORE, 
THE JTWC FORECAST IS POSITIONED NEAR THE MULTI-MODEL CONSENSUS MEAN 
WITH HIGH CONFIDENCE. INTENSITY GUIDANCE IS ALSO IN GOOD AGREEMENT, 
WITH THE MAJORITY OF THE MODELS DEPICTING WEAKENING TO 30 KTS OR LESS 
WITHIN 24 HOURS. SHIPS-GFS AND CTCX ARE THE SOLE OUTLIERS, MAINTAINING 
A 35-KT SYSTEM SLIGHTLY LONGER AND EXTENDING THE DISSIPATION TIMELINE 
TO TAU 36. 

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