WDPN33 PGTW 250300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 19W (ATSANI) WARNING 
NR 011//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 19.2N 138.2E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 378 NM SOUTH-SOUTHWEST OF IWO TO
   MOVEMENT PAST 6 HOURS: NORTHWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL
DEPRESSION (TD) 19W (ATSANI) AS A HIGHLY SHEARED, ELONGATED, AND
FULLY EXPOSED LOW-LEVEL CIRCULATION CENTER (LLCC). 19W REMAINS
TRAPPED WITHIN THE STRONG LOW-LEVEL SOUTHEASTERLY FLOW ASSOCIATED
WITH THE INFLOW INTO TYPHOON 17W. ANIMATED MSI ALSO REVEALS THAT
19W IS BECOMING INCREASINGLY DISORGANIZED AND RAGGED, WITH A CLEAR
LLCC BECOMING DIFFICULT TO IDENTIFY. ENVIRONMENTAL ANALYSIS REVEALS
AN UNFAVORABLE ENVIRONMENT, CHARACTERIZED BY HIGH (25-30 KTS)
VERTICAL WIND SHEAR (VWS), WEAK OUTFLOW ALOFT, AND PERSISTENT
DEEP-LAYER DRY AIR ENTRAINMENT, INSIGNIFICANTLY OFFSET BY THE WARM
(29-30 C) SEA SURFACE TEMPERATURES (SST). THE INITIAL POSITION IS
PLACED WITH HIGH CONFIDENCE BASED ON THE FULLY EXPOSED LLCC IN
ANIMATED MSI. THE INITIAL INTENSITY OF 30 KTS IS ASSESSED WITH
MEDIUM CONFIDENCE BASED ON THE AUTOMATED CIMSS ESTIMATES AND AGENCY
DVORAK FIXES LISTED BELOW.

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

CURRENT STEERING MECHANISM: STRONG LOW-LEVEL SOUTHEASTERLIES AND
THE SOUTHEASTWARD EXTENSION OF A SUBTROPICAL RIDGE CENTERED OVER
JAPAN

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   CIMSS SATCON: 47 KTS AT 242320Z
   CIMSS ADT: 33 KTS AT 250050Z
   CIMSS AIDT: 36 KTS AT 150050Z
   CIMSS D-PRINT: 25 KTS AT 250050Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 25-30 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: WEAK EQUATORWARD
   OTHER FACTORS: PERSISTENT DEEP-LAYER DRY AIR ENTRAINMENT

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   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: TD 19W IS FORECAST TO CONTINUE TRACKING
GENERALLY NORTHWARD, WITH A NORTHWESTWARD TURN EXPECTED WITHIN THE
NEXT 12 HOURS. 19W WILL TRACK NORTHWESTWARD IN THE WAKE OF TYPHOON
17W THROUGH TAU 24, AT WHICH POINT, IT IS EXPECTED TO GET
OVERWHELMED BY THE INCREASINGLY HOSTILE ENVIRONMENT AND DISSIPATE.
VWS IS EXPECTED TO REMAIN BETWEEN 25-35 KTS THROUGH TAU 24. THE VWS
COUPLED WITH THE SIGNIFICANT DRY AIR ENTRAINMENT ARE EXPECTED TO BE
THE PRIMARY FACTORS FOR DISSIPATION. 

MODEL DISCUSSION: DETERMINISTIC MODEL TRACK GUIDANCE IS IN STRONG
AGREEMENT THROUGH TAU 24, THOUGH MANY MODELS DROP THE VORTEX AFTER
TAU 12. AS A RESULT, THE JTWC TRACK FORECAST IS PLACED CLOSE TO THE
MULTI-MODEL CONSENSUS WITH HIGH CONFIDENCE. RELIABLE INTENSITY AIDS
ARE ALSO IN STRONG AGREEMENT THAT 19W WILL STEADILY WEAKEN UNTIL
DISSIPATION NO LATER THAN TAU 24, LENDING HIGH CONFIDENCE TO THE
JTWC INTENSITY FORECAST. 

FORECAST CONFIDENCE:
   TRACK 00-72 HR: HIGH
   INTENSITY 00-72 HR: HIGH//
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