WDPS31 PGTW 161500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 19P (MEGAN)
WARNING NR 005//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 14.5S 137.6E
   INITIAL INTENSITY: 55 KTS
   GEOGRAPHIC REFERENCE: 409 NM EAST-SOUTHEAST OF DARWIN, AUSTRALIA
   MOVEMENT PAST 6 HOURS: SOUTHWESTWARD AT 04 KTS
   SIGNIFICANT WAVE HEIGHT: 22 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL
CYCLONE (TC) 19P (MEGAN) SHOWING DEEP, PERSISTENT CENTRALIZED
CONVECTION MOSTLY OBSCURING THE ASSESSED LOW-LEVEL CIRCULATION
CENTER (LLCC). NOTEWORTHY, A LARGE CIRRUS CANOPY REALLY BLOSSOMED
OUT OVER THE PAST SIX HOURS AND COMPLETELY OBSCURED THE NORTHERN
PERIPHERY OF THE MIDDLE AND LOWER LEVELS. SPIRAL BANDS OF DEEP
CONVECTION FILL OUT THE WESTERN SEMICIRCLE AND SHALLOW BANDING IS
OBSERVABLE THROUGHOUT THE SOUTHEASTERN QUADRANT WRAPPING INTO THE
LLCC. THE INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED
ON RADAR, SURFACE OBSERVATIONS, AND A 161200Z HIMAWARI-9 ENHANCED
INFRARED SATELLITE IMAGE. THE INITIAL INTENSITY OF 50 KTS IS
ASSESSED WITH MEDIUM CONFIDENCE BASED ON SURFACE OBSERVATIONS AND
THE SUBJECTIVE AND OBJECTIVE INTENSITY ESTIMATES LISTED BELOW.

INITIAL WIND RADII BASIS: PERSISTENCE

CURRENT STEERING MECHANISM: WESTERN PERIPHERY OF A MID-LEVEL NEAR
EQUATORIAL RIDGE (NER) TO THE EAST-NORTHEAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   KNES: T3.5 - 55 KTS
   CIMSS ADT: 57 KTS AT 161130Z
   CIMSS ADT: 59 KTS AT 161200Z
   CIMSS DPRINT: 50 KTS AT 161300Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 10-15 KTS
   SST: 30-31 CELSIUS
   OUTFLOW: MODERATE EQUATORWARD

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: TC 19P (MEGAN) IS FORECAST TO TRACK
SOUTH-WESTWARD FROM TAU 00 TO TAU 36 FOLLOWING THE STEERING
INFLUENCE OF AN EXTENSION OF A NEAR-EQUATORIAL RIDGE TO THE
EAST-NORTHEAST. ALONG-TRACK, A FAVORABLE ENVIRONMENT HAVING LOW TO
MODERATE (10-15 KTS) VERTICAL WIND SHEAR (VWS), VERY WARM (30-31 C)
SEA SURFACE TEMPERATURES, A MOIST MID LEVEL (RELATIVE HUMIDITY NEAR
70 PCT), OFFSET BY MODERATE DIVERGENCE ALOFT. OUTFLOW CONDITIONS
ALOFT ARE FORECAST TO WORSEN FROM TAU 00 TO TAU 24, WHICH IS THE
MAJOR RESTRAINT ON THE SYSTEM OVER THIS INTERVAL. HOWEVER, WITH ALL
OTHER ENVIRONMENTAL FACTORS ASSESSED AS FAVORABLE FOR FURTHER
INTENSIFICATION TO OCCUR, THE SYSTEM IS EXPECTED TO INTENSIFY TO
PEAK INTENSITY NEAR 70 KTS BY AROUND TAU 24. LANDFALL IS
ANTICIPATED TO OCCUR NEAR TAU 48 ALONG THE SOUTHERN COAST OF THE
GULF OF CARPENTARIA. DISSIPATION IS ANTICIPATED TO OCCUR PRIOR TO
TAU 72 AS THE SYSTEM MOVES INLAND OVER NORTHERN AUSTRALIA.

MODEL DISCUSSION: GLOBAL NUMERICAL MODEL GUIDANCE IS IN OVERALL
GOOD AGREEMENT REGARDING TRACK, WITH ALL JTWC CONSENSUS MEMBERS
EXCEPT NAVGEM SUGGESTING A SOUTHWARD TRACK COMPONENT FROM TAU 00 TO
TAU 48. AT TAU 48, ALL MEMBERS THEN TRACK THE SYSTEM
WEST-SOUTHWESTWARD TO WESTWARD THROUGH TAU 72. REMOVING NAVGEM, A
CROSS-TRACK SPREAD OF 82NM IS PRESENT BETWEEN THE ECMWF ENSEMBLE
MEAN AND GALWEM BY TAU 48, LEAVING SOME UNCERTAINTY AS TO WHERE
ALONG THE SOUTHERN GULF OF CARPENTARIA THE SYSTEM WILL TRACK
ASHORE. INTENSITY GUIDANCE INCLUDES INDICATION THAT RAPID
INTENSIFICATION MAY BE OBSERVED IN THE NEXT 24 HOURS. THOUGH, THE
PROBABILITY OF OCCURRENCE ASSOCIATED WITH THESE AIDS IS NEAR 30 TO
40 PERCENT. INTENSITY CONSENSUS MEMBERS ARE UNIFORM IN NATURE,
INDICATING A RISE IN INTENSITY TO A PEAK INTENSITY NEAR TAU 24,
FOLLOWED BY A WEAKENING TREND AS THE SYSTEM TRACKS WESTWARD OVER
LAND.

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