WDPN31 PGTW 260900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 18W (CIMARON) 
WARNING NR 008//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 28.0N 132.3E
   INITIAL INTENSITY: 25 KTS
   GEOGRAPHIC REFERENCE: 256 NM EAST-NORTHEAST OF KADENA AB
   MOVEMENT PAST 6 HOURS: SOUTHWARD AT 02 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A RAGGED,
INCREASINGLY ELONGATED AND EXPOSED LOW LEVEL CIRCULATION CENTER
(LLCC). A RECENT FLARE UP OF CONVECTIVE ACTIVITY IS SEEN IN THE
NORTHEAST QUADRANT OF THE CIRCULATION, ALONG A CONVERGENT ASYMPTOTE
IN THE LOW-LEVEL FLOW AND IN AN AREA OF REMNANT DEEP MOISTURE. THE
REMAINDER OF THE CIRCULATION IS SMOTHERED IN A DEEP LAYER OF DRY
AIR IN THE MID-LEVELS. A 260522Z SCATTEROMETER PASS REVEALED AN
ASYMMETRIC WIND FIELD, WITH 25-27 KNOT NORTHEASTERLY FLOW STREAMING
SOUTHWARD OFF THE SOUTHEAST COAST OF KYUSHU AND ANOTHER PATCH OF 25
KNOT WINDS FAR OFF TO THE SOUTHEAST, WHILE THE REMAINDER OF THE
WIND FIELD REMAINS BELOW 25 KNOTS. A SHIP OBSERVATION FROM 260700Z,
APPROXIMATELY 90NM TO THE NORTHWEST REPORTED NORTHEAST WINDS OF 28
KNOTS, WHICH CONFIRMS THE EARLIER SCATTEROMETER DATA AND VERIFIES
THE WIND FIELD ASYMMETRIES. THE INITIAL POSITION IS ASSESSED WITH
HIGH CONFIDENCE BASED ON THE EXPOSED LLCC IN THE MSI. THE INITIAL
INTENSITY IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE SUBJECTIVE
AND OBJECTIVE INTENSITY ESTIMATES NOTED BELOW AND THE ASCAT DATA
MENTIONED ABOVE. THE SYSTEM CURRENTLY SITS AT THE FAR END OF A
STATIONARY BOUNDARY EXTENDING SOUTHWEST FROM A SUBTROPICAL LOW
(INVEST 95W) EAST OF TOKYO. ANALYSIS REVEALS AN UNFAVORABLE
ENVIRONMENT CHARACTERIZED BY LOW TO MODERATE (15-20 KNOTS) VWS,
WARM SSTS AND MODERATE POLEWARD OUTFLOW, OFFSET BY EXTREMELY DRY
AIR AND CONVERGENCE UPPER-LEVEL FLOW ALONG THE WESTERN PERIPHERY.
OVER THE PAST SIX HOURS THE SYSTEM HAS TRAVELED
SOUTH-SOUTHWESTWARD, REACHING ITS FURTHEST SOUTHWARD POINT AROUND
0300Z BEFORE TURNING BACK NORTHWARD. HENCE THE BEST TRACK SHOWS
WHAT APPEARS TO BE A SOUTHWARD TRACK MOTION BUT IN REALITY THE
SYSTEM IS DRIFTING BACK NORTHWARD OR QUASI-STATIONARY.

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

CURRENT STEERING MECHANISM: WEAK STEERING PATTERN, WITH STRONG
LOW-LEVEL RIDGING FAR TO THE EAST, RIDGING OVER NORTHEASTERN CHINA
AND A LOW-LEVEL TROUGH EXTENDING FROM LUZON, THROUGH TD 18W AND
ALONG THE STATIONARY BOUNDARY CONNECTING TO INVEST 95W. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T1.5 - 25 KTS
   RJTD: T1.5 - 25 KTS
   RCTP: T1.0 - 25 KTS
   KNES: T1.0 - 25 KTS
   CIMSS ADT: 33 KTS AT 260530Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 15-20 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: MODERATE POLEWARD
   OTHER FACTORS: EXTENSIVE MID-LEVEL DRY AIR. 

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: HIGH
   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: FOR THE NEXT 12 HOURS OR SO, TD 18W (CIMARON)
WILL CONTINUE TO DRIFT GENERALLY NORTHWARD IN THE WEAK STEERING
PATTERN DESCRIBED ABOVE. AFTER TAU 12, AS THE STATIONARY BOUNDARY
EXTENDS FURTHER SOUTHWESTWARD, TD 18W WILL BEGIN TO MOVE
NORTHEASTWARD AT A SLIGHT FASTER CLIP, AS THE GRADIENT TIGHTENS
ALONG THE STATIONARY BOUNDARY. DEEP-LAYER SHEAR IS EXPECTED TO
INCREASE DRAMATICALLY AFTER TAU 24 AS THE SYSTEM BEGINS TO MOVE
UNDER THE SOUTHERN EDGE OF A STRONG 300MB JET MAX OVER JAPAN.
COMBINED WITH FURTHER DRY AIR ENTRAINMENT, TD 18W WILL BE
OBLITERATED AFTER TAU 24, DISSIPATING AS A TROPICAL CYCLONE BY TAU
36 SOUTHEAST OF KYUSHU. IT SHOULD BE NOTED THAT WHILE TD 18W AS A
DISTINCT ENTITY WILL NO LONGER EXIST AFTER TAU 36, THE REMNANT
VORTICITY MAXIMUM IS EXPECTED TO CONTINUE MOVING NORTHEASTWARD
ALONG A REINVIGORATED COLD FRONT. THE 260000Z GFS SHOWS THE AREA OF
VORTICITY REINTENSIFYING ALONG THE LEADING EDGE OF A NORTHEASTERLY
SURGE AROUND TAU 84, BRIEFLY REACHING 30-35 KNOTS WHILE MOVING
SOUTHWESTWARD IN A WEAK BINARY INTERACTION WITH THE CIRCULATION
CURRENTLY DESIGNATED INVEST 95W. WHILE CONSIDERED A LOW PROBABILITY
AT THE MOMENT, THE SYSTEM WILL BE CLOSELY MONITORED FOR THE
POTENTIAL OF THIS SCENARIO. 

MODEL DISCUSSION: DETERMINISTIC TRACK GUIDANCE IS IN GOOD AGREEMENT
THAT THE SYSTEM WILL TRACK NORTH AND TURN NORTHEASTWARD AFTER TAU
12. HOWEVER, ALL OF THE AVAILABLE GUIDANCE, WITH THE EXCEPTION OF
THE HAFS-A, ARE PUSHING THE SYSTEM POLEWARD MUCH TOO QUICKLY BASED
ON THE RECENT TRACK MOTION AND ANALYSIS OF THE STEERING PATTERN.
THUS THE JTWC FORECAST TRACK, WHILE CONSISTENT IN THE DIRECTION OF
THE FORECAST TRACK, IS MUCH SLOWER THAN THE BULK OF THE GUIDANCE.
INTENSITY GUIDANCE IS IN GENERALLY GOOD AGREEMENT, THOUGH THE
MESOSCALE COAMPS-TC (GFS VERSION) SHOWS A POSSIBLE
REINTENSIFICATION AFTER TAU 24 AS THE SYSTEM TRACKS ALONG THE COLD
FRONT. THE HAFS-A ON THE OTHER HAND, DISSIPATES THE SYSTEM AFTER
TAU 24, WITH THE CONSENSUS LYING ROUGHLY IN BETWEEN. THE JTWC
FORECAST FOLLOWS THE HAFS-A FORECAST, BUT IT REMAINS POSSIBLE THAT
BAROCLINIC FORCING COULD ALLOW FOR SOME REINTENSIFICATION AS THE
SYSTEM MOVES UP THE FRONTAL BOUNDARY. 

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