WDPS31 PGTW 102100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 03P (JASPER) WARNING 
NR 024//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 17.5S 151.5E
   INITIAL INTENSITY: 50 KTS
   GEOGRAPHIC REFERENCE: 329 NM EAST OF CAIRNS, AUSTRALIA
   MOVEMENT PAST 6 HOURS: WEST-SOUTHWESTWARD AT 12 KTS
   SIGNIFICANT WAVE HEIGHT: 24 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TROPICAL CYCLONE (TC) 03P (JASPER) CONTINUES TO WEAKEN AFTER HAVING
BEEN TOPPED BY AN EXTREMELY DRY AIR MASS ENTRENCHED ABOVE 400MB.
ANIMATED ENHANCED INFRARED (EIR) AN PROXY VISIBLE (PROXYVIS)
SATELLITE IMAGERY DEPICTS A NAKED LOW LEVEL CIRCULATION CENTER
(LLCC) DEVOID OF ANY SIGNIFICANT CONVECTIVE ACTIVITY THAT THE DRY
AIR HAS COMPLETELY ENGULFED THE CIRCULATION. A 101748Z SSMIS 37GHZ
IMAGE SHOWS THAT THE LOW-LEVEL STRUCTURE REMAINS INTACT HOWEVER,
WITH A WELL-DEFINED MICROWAVE EYE-LIKE FEATURE AND SHALLOW BANDING
FEATURES WRAPPING INTO THE LLCC. THE INITIAL POSITION IS ASSESSED
WITH HIGH CONFIDENCE BASED ON THE ANIMATED PROXYVIS, THE
AFOREMENTIONED MICROWAVE IMAGE, AND SURFACE OBSERVATIONS FROM LIHOU
LIGHTHOUSE WHICH SHOWED THE CENTER OF THE SYSTEM PASSED VERY CLOSE
TO OR DIRECTLY OVER THE STATION AROUND 1500Z, WITH THE WINDS
VEERING SHARPLY FROM SOUTHWESTERLY TO NORTHERLY. THE INITIAL
INTENSITY IS ASSESSED AT 50 KNOTS, HEDGED ABOVE THE DVORAK-BASED
TECHNIQUES WHICH ARE TOO LOW AFTER THE COLLAPSE OF THE CONVECTION.
HOWEVER, A SENTINEL-1A SAR PASS FROM 100831Z SHOWED WINDS UP TO 63
KNOTS ACROSS THE MAJORITY OF SOUTHERN HEMISPHERE OF THE SYSTEM,
SUGGESTING THAT WHILE THE CONVECTION IS GONE, THE LOW-LEVEL WIND
FIELD IS ONLY SLOWLY WINDING DOWN. PRESSURE READINGS FROM LIHOU
LIGHTHOUSE AS THE CENTER PASSED WERE AS LOW AS 983MB, WHICH
PROVIDES SUPPORT FOR A 50-55 KNOT INTENSITY BASED ON THE KNAFF-ZEHR
WIND PRESSURE RELATIONSHIP. THE SYSTEM HAD PICKED UP SOME SPEED
OVERNIGHT, BUT HAS NOW BEGUN TO SLOW DOWN AGAIN, AND SHIFTED TO A
MORE WEST-SOUTHWEST HEADING. THE ENVIRONMENT REMAINS MARGINAL AT
BEST, FOR WHILE SHEAR HAS DROPPED OFF TO LOW LEVELS (10-15 KNOTS)
AND OUTFLOW REMAINS MODERATE TO THE SOUTH, THE DRY AIR IS
OVERWHELMING ALL THE OTHER FACTORS.

INITIAL WIND RADII BASIS: SAR DATA 

CURRENT STEERING MECHANISM: NORTHWEST PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) CENTERED TO THE SOUTHEAST. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   KNES: T2.5 - 35 KTS
   APRF: T3.0 - 45 KTS
   CIMSS SATCON: 45 KTS AT 101541Z
   CIMSS ADT: 39 KTS AT 101730Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY
UNFAVORABLE
   VWS: 10-15 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: MODERATE POLEWARD
   OTHER FACTORS: EXTREMELY DRY AIR ENGULFING THE SYSTEM.

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: HIGH
   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 SPEEDING UP AND TAKING A MORE
SOUTHWESTWARD TRACK OVERNIGHT, TC 03P APPEARS TO BE SLOWING DOWN A
BIT, AND SHIFTING TO A SLIGHTLY MORE WEST-SOUTHWESTWARD TRACK OVER
THE PAST SIX HOURS. AS THE SYSTEM HAS CONTINUED TO WEAKEN, THE
DEPTH OF THE STEERING LEVEL HAS SHIFTED DOWNWARDS, WITH THE TOP OF
THE STEERING COLUMN NOW ASSESSED TO BE AROUND 500MB. AT 500MB, THE
STEERING RIDGE IS ORIENTED ON A MORE SOUTHWEST TO NORTHEAST AXIS,
WHICH EXPLAINS THE RECENT SOUTHWESTWARD TRACK MOTION. LOOKING
FORWARD, THE RIDGE IS STILL ANTICIPATED TO SHIFT NORTHWARD TO A
POSITION NORTH OF BRISBANE OVER THE NEXT COUPLE OF DAYS, WHICH WILL
ALLOW TC 03P TO TRACE A SHALLOW WAVE-LIKE TRACK THROUGH TAU 48.
LANDFALL IS NOW EXPECTED AROUND TAU 48, VERY NEAR CAIRNS,
AUSTRALIA. AFTER LANDFALL, THE SYSTEM WILL CONTINUE TRACKING
WESTWARD OVER THE FAR SOUTHERN PORTION OF THE CAPE YORK PENINSULA.
IN TERMS OF INTENSITY, THE CONTINUED PRESENCE OF THE DRY AIR ALOFT
WILL CAP ANY CONVECTION WHICH MANAGES TO COOK OFF FOR THE NEXT 24
HOURS OR SO. THUS THE SYSTEM WILL CONTINUE TO SLOWLY WEAKEN AS THE
WIND FIELD SPINS DOWN. GLOBAL AND MESOSCALE MODELS CONTINUE TO
INSIST THAT THE ENVIRONMENT WILL MOISTEN UP AFTER TAU 24, WHILE
SHEAR IS EXPECTED TO REMAIN LOW AND MODERATE POLEWARD OUTFLOW
PERSISTS. THIS SHOULD ALLOW THE SYSTEM TO REINTENSIFY TO 50-55
KNOTS BY TAU 48. AFTER LANDFALL, TC 03P WILL RAPIDLY WEAKEN AND
ULTIMATELY DISSIPATE PRIOR TO REACHING THE GULF OF CARPENTARIA. 

MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE IS IN FAIRLY GOOD
AGREEMENT, WITH THE NOTABLE EXCEPTION OF THE HAFS-A AND HWRF
TRACKERS WHICH CONTINUE TO SHOW A MORE SOUTHWARD TRACK, WITH THE
SYSTEM PASSING SOUTH OF FLINDERS REEF AND MAKING LANDFALL WELL
SOUTH OF CAIRNS. THE REMAINDER OF THE GUIDANCE IS TIGHTLY GROUPED
AROUND THE CONSENSUS MEAN. THE JTWC FORECAST TRACK IS WELL SOUTH OF
THE CONSENSUS MEAN THROUGH TAU 24, HEDGED CLOSER TO THE HAFS-A AND
HWRF SOLUTIONS, AS THESE TWO MODELS SUCCESSFULLY PREDICTED THE
EARLIER JOG TO THE SOUTHWEST. AFTER TAU 24, THE JTWC FORECAST
TRACKS CLOSER TO THE CONSENSUS MEAN. CONFIDENCE IS MEDIUM THROUGH
THE FORECAST PERIOD. INTENSITY GUIDANCE IS IN FAIR AGREEMENT, WITH
A FAIRLY LARGE SPREAD IN INTENSIFICATION SOLUTIONS, PARTICULARLY
AFTER TAU 24. THE BULK OF THE GUIDANCE INDICATES NO
REINTENSIFICATION, WHILE THE COAMPS-TC (NAVGEM AND GFS) ARE THE
ONLY MODELS SUGGESTING A REINTENSIFICATION PHASE PRIOR TO LANDFALL.
THE JTWC FORECAST TRACKS THE MEAN THROUGH TAU 24, THEN SHIFTS ABOUT
HIGHER THAN THE MEAN, UP TO 10 KNOTS HIGHER AT TAU 48, BUT IN LINE
WITH THE COAMPS-TC GUIDANCE. CONFIDENCE IN THE INTENSITY FORECAST
IS LOW DUE TO THE UNCERTAINTIES REGARDING TIMING OF WHEN THE
ATMOSPHERE WILL MOISTEN ENOUGH TO ALLOW A RESURGENCE IN CONVECTION.


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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