WDXS31 PGTW 180900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 29S (ERROL) WARNING NR 
027//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 16.0S 123.9E
   INITIAL INTENSITY: 40 KTS
   GEOGRAPHIC REFERENCE: 150 NM NORTHEAST OF BROOME, AUSTRALIA
   MOVEMENT PAST 6 HOURS: EASTWARD AT 05 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL
CYCLONE 29S WITH AN EXPOSED LOW-LEVEL CIRCULATION CENTER (LLCC)
JUST OFF THE COAST OF NORTHEAST OF KOOLAN ISLAND. CONVECTION CONTINUES
TO BE HEAVILY SHEARED OFF TOWARD THE EAST. ENVIRONMENTAL ANALYSIS
INDICATES THAT 29S IS IN AN UNFAVORABLE ENVIRONMENT CHARACTERIZED
BY STRONG POLEWARD OUTFLOW AND VERY WARM (30-31 C) SEA SURFACE
TEMPERATURES GREATLY OFFSET BY HIGH (25-30 KTS) VERTICAL WIND SHEAR
AND SIGNIFICANT DRY AIR INTRUSION FROM THE WEST. THE INITIAL
POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE EXPOSED LLCC
IN ANIMATED MSI. THE INITIAL INTENSITY OF 40 KTS IS ASSESSED WITH
MEDIUM CONFIDENCE BASED ON THE 180047Z ASCAT PASS, THE FALLING
AGENCY DVORAK FIXES, AND THE OBJECTIVE INTENSITY ESTIMATES ARE LISTED
BELOW.

INITIAL WIND RADII BASIS: PERSISTENCE FROM THE 18OO47Z METOP-C
SCATTEROMETER DATA

CURRENT STEERING MECHANISM: LONGWAVE TROUGH TO THE SOUTH OF THE
SYSTEM AND ASSOCIATED DEEP-LAYER WESTERLY FLOW.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   KNES: T4.0 - 65 KTS
   DEMS: T3.5 - 55 KTS
   APRF: T2.5 - 35 KTS
   CIMSS ADT: 47 KTS AT 180610Z
   CIMSS AIDT: 55 KTS AT 180610Z
   CIMSS DPRINT: 31 KTS AT 180610Z
   CIMSS DMINT: 26 KTS AT 180526Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 25-30 KTS
   SST: 30-31 CELSIUS
   OUTFLOW: STRONG POLEWARD
   OTHER FACTORS: LAND INTERACTION AND DRY AIR INTRUSION FROM THE
WEST

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: AFTER MAKING A SOMEWHAT UNEXPECTED STALL OFF
THE COAST, 29S IS FORECAST TO BEGIN TRACKING INLAND OVER THE NEXT
12-24 HOURS. ENVIRONMENTAL PARAMETERS WILL CONTINUE TO WORSEN AS THE
CIRCULATION MAKES LANDFALL, WITH SHEAR VALUES OF 35-40 KTS AND DRY
AIR ENTRAINMENT. A DROP TO BELOW 35 KTS IS EXPECTED WITHIN THE NEXT
12 HOURS AS TERRAIN INTERACTION FURTHER AIDS IN THE EROSION OF THE
VORTEX. CURRENT GUIDANCE HAS NO DEPICTION OF A RECURVE IN THE TRACK
OR REGENERATION POTENTIAL.

MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE IS IN GOOD
AGREEMENT ON A CONTINUED EASTWARD TO EAST-SOUTHEASTWARD TRACK OVER
THE NEXT 24 HOURS. SOME MODELS BEGIN TO LOSE THE VORTEX AS SOON AS
TAU 12 THOUGH, LENDING ONLY MEDIUM CONFIDENCE IN THE JTWC TRACK
FORECAST. INTENSITY GUIDANCE IS IN A CLOSE GROUPING, ALL SUGGESTING
FURTHER WEAKENING THROUGHOUT THE FORECAST PERIOD. THE JTWC
INTENSITY FORECAST IS PLACED CLOSE TO THE MULTI-MODEL CONSENSUS
WITH HIGH CONFIDENCE. 

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