WDXS31 PGTW 020300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 04S (ALVARO) WARNING NR 
004//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 21.4S 44.9E
   INITIAL INTENSITY: 45 KTS
   GEOGRAPHIC REFERENCE: 210 NM SOUTHWEST OF ANTANANARIVO, MADAGASCAR
   MOVEMENT PAST 6 HOURS: EASTWARD AT 10 KTS
   SIGNIFICANT WAVE HEIGHT: XX FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A
RAPIDLY DETERIORATING CIRCULATION THAT IS TRANSITING OVER
INCREASINGLY MORE MOUNTAINOUS TERRAIN. A 012214Z ATMS 183GHZ
MICROWAVE IMAGE INDICATES DEEP CENTRAL CONVECTION, DEVOID OF ANY
SURROUNDING BANDING FEATURES. A LACK OF OTHER IMAGERY OR
OBSERVATION DATA MEANS THE INITIAL POSITION IS PLACED WITH
RELATIVELY LOW CONFIDENCE. THE INITIAL INTENSITY OF 45 KTS IS
ASSESSED WITH LOW CONFIDENCE BASED ON AUTOMATED INTENSITY ESTIMATES
LIKE DPRINT INDICATING 57KTS WHILE STORM STRUCTURE AND MODEL
GUIDANCE SUPPORT A LOWER INTENSITY COMMENSURATE WITH A SHARPER
WEAKENING TREND.

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

CURRENT STEERING MECHANISM: NEAR EQUATORIAL RIDGE POSITIONED TO THE
NORTHEAST, STEERING THE SYSTEM GENERALLY EASTWARD.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: NO CURRENT ESTIMATE

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY UNFAVORABLE
   VWS: 20-25 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: MODERATE POLEWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: LOW
   INITIAL INTENSITY: LOW
   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: OVER THE NEXT 12-20 HOURS, THE MOUNTAINOUS
EASTERN COAST OF MADAGASCAR WILL PROGRESSIVELY TEAR APART 04S. BY
TAU 24, WHEN THE CIRCULATION FINALLY RE-ENTERS OPEN WATERS, IT MAY
BRIEFLY INTENSIFY TO AROUND 40KTS BUT INCREASING VERTICAL WIND
SHEAR (VWS) AND DRY AIR ENTRAINMENT WILL QUICKLY RAIN ON THAT
PARADE. AS THE NER TO THE NORTH BUILDS POLEWARD, 04S WILL SHIFT TO
A SOUTHEASTWARD COURSE. BY TAU 48, VWS SURPASSES 35KTS AND COOLING
SSTS FURTHER EXACERBATE AN ALREADY DETERIORATING ENVIRONMENT,
RESULTING IN A STEADING WEAKENING TREND THROUGH THE FORECAST
PERIOD. THOUGH 04S BEGINS TO INTERACT WITH THE SUBTROPICAL
WESTERLIES AND ASSOCIATED BAROCLINIC ZONE BY 96, IT IS ANTICIPATED
THAT THE SYSTEM WILL DISSIPATE BEFORE ANY MEASURABLE SUBTROPICAL
CHARACTERISTICS CAN BE OBTAINED.

MODEL DISCUSSION: WITH THE EXCEPTION OF NVGM, NUMERICAL MODELS ARE
IN GOOD AGREEMENT, SHOWING A 160NM SPREAD BY TAU 72. FOR THIS
REASON, THE JTWC FORECAST TRACK IS PLACED WITH OVERALL MEDIUM
CONFIDENCE. RELIABLE MODEL INTENSITY GUIDANCE IS IN POOR AGREEMENT
WITH A 25KT DISCREPANCY BY TAU 24 THAT WORSENS TO 30KTS BY TAU 96.
DECAY-SHIPS AND GFS ARE THE LOWEST MEMBERS WHILE HAFS AND COAMPS-TC
INDICATE 45KTS THROUGH TAU 84. FOR THIS REASON, THE JTWC INTENSITY
FORECAST IS PLACED WITH OVERALL LOW CONFIDENCE.

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: MEDIUM
   TRACK 72-120 HR: MEDIUM
   INTENSITY 0 - 72 HR: LOW
   INTENSITY 72-120 HR: LOW//
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