WDPN32 PGTW 262100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 19W (NINETEEN) 
WARNING NR 002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 17.8N 146.1E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 498 NM SOUTH-SOUTHEAST OF IWO TO
   MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 07 KTS
   SIGNIFICANT WAVE HEIGHT: 15 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TROPICAL
DEPRESSION 19W WITH A LARGE AREA OF DEEP CONVECTION FLARING ALONG
THE SOUTHERN PERIPHERY OF THE MOSTLY OBSCURED LOW-LEVEL CIRCULATION
CENTER (LLCC). STRONG OUTFLOW IS REPRESENTED BY THE PRESENCE OF
CIRRUS FILAMENTS EXPANDING OUTWARD FROM THE SYSTEM. ENVIRONMENTAL
ANALYSIS INDICATES THAT 19W IS IN A MARGINALLY FAVORABLE
ENVIRONMENT FOR FURTHER INTENSIFICATION CHARACTERIZED BY THE STRONG
RADIAL OUTFLOW ALOFT, LOW (10-15 KTS) VERTICAL WIND SHEAR, AND WARM
SEA SURFACE TEMPERATURES OFFSET BY DRY AIR PLACED OVER THE
NORTHWESTERN AND WESTERN SECTORS OF THE SYSTEM. THE INITIAL
POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED ON THE LOW-LEVEL
CLOUD LINES SEEN IN THE ANIMATED EIR IMAGERY. THE INITIAL INTENSITY
OF 30 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE AGENCY
DVORAK AND OBJECTIVE INTENSITY ESTIMATES LISTED BELOW.

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

CURRENT STEERING MECHANISM: SOUTHWESTERN PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) POSITIONED TO THE NORTHEAST.  

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   RJTD: T1.5 - 25 KTS
   KNES: T2.0 - 30 KTS
   CIMSS SATCON: 34 KTS AT 261800Z
   CIMSS ADT: 34 KTS AT 261800Z
   CIMSS AIDT: 33 KTS AT 261800Z
   CIMSS DMINT: 32 KTS AT 291800Z
   CIMSS DPRINT: 31 KTS AT 291800Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 10-15 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG RADIAL
   OTHER FACTORS: DRY AIR TO THE WEST AND NORTHWEST.

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   INITIAL INTENSITY: MEDIUM
   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: 19W IS FORECAST TO CONTINUE TRACKING
NORTHWESTWARD, ALONG THE SOUTHWESTERN PERIPHERY OF THE STR TO THE
NORTHEAST THROUGH TAU 48. NEAR TAU 48, 19W IS FORECAST TO BEGIN
ROUNDING THE AXIS OF THE RIDGE AND TURN MORE NORTHWARD. AT TAU 72,
19W WILL START TO TRACK NORTHEASTWARD AFTER ROUNDING THE RIDGE AXIS
AND CONTINUE ON THAT TRACK UNTIL IT ENTERS THE BAROCLINIC ZONE AT
AROUND TAU 120. REGARDING INTENSITY, 19W IS EXPECTED TO MAINTAIN
AROUND 30-35 KTS THROUGH TAU 36 DUE TO THE INCREASING VERTICAL WIND
SHEAR AND REDUCED OUTFLOW AS A TUTT CELL TO ITS NORTHEAST
PROPAGATES WESTWARD ALMOST DIRECTLY ON TOP OF THE SYSTEM, HINDERING
OUTFLOW. DRY AIR WILL ALSO REMAIN A FACTOR IN THE HINDRANCE OF
FURTHER INTENSIFICATION. HOWEVER, AFTER TAU 36, THE TUTT CELL IS
EXPECTED TO HAVE MOVED WESTWARD OF THE SYSTEM, ALLOWING FOR A MORE
CONDUCIVE ENVIRONMENT. THE ENVIRONMENT IS ALSO ANTICIPATED TO
MOISTEN AFTER THE TUTT CELL PASSES ALLOWING FOR INTENSIFICATION. AS
A RESULT, 19W IS FORECAST TO STEADILY INTENSIFY TO AROUND 60 KTS AT
TAU 96. NEAR TAU 96, THE SYSTEM WILL BEGIN INTERACTING WITH THE
BAROCLINIC ZONE AND WIND SHEAR WILL QUICKLY RISE, WEAKENING 19W TO
AROUND 50 KTS AS IT TRANSITIONS INTO AN EXTRATROPICAL CYCLONE. 

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT
CONCERNING THE TRACKING OF 19W WITH A 210 NM CROSS TRACK SPREAD AT
TAU 48. ALONG TRACK SPREAD DOES INCREASE CONSIDERABLY AFTER TAU 48
AS THE SYSTEM GETS POLEWARD OF THE RIDGE AXIS THOUGH. GFS IS THE
FASTEST MODEL WHILE THE COMBINATION OF UKMET AND GALWEM ARE THE
SLOWEST. THE JTWC TRACK FORECAST IS PLACED NEAR THE MIDPOINT OF THE
TWO SCENARIOS, CLOSE TO CONSENSUS, WITH HIGH CONFIDENCE THROUGH TAU
 72 WITH MEDIUM CONFIDENCE THEREAFTER. INTENSITY GUIDANCE IS IN
MODERATE AGREEMENT WITH STAGNANT INTENSITY THROUGH TAU 36. PEAK
INTENSITIES VARY WITH HAFS-A SUGGESTING A PEAK OF AROUND 50 KTS
WHILE GFS AND THE COAMPS-TC (GFS BASED) BOTH SUGGEST A PEAK OF
AROUND 70 KTS AT TAU 96. THE JTWC INTENSITY FORECAST IS PLACED WITH
OVERALL MEDIUM CONFIDENCE WITH A PEAK OF 60 KTS BETWEEN THE TWO
EXTREMES. 

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