Advisories

WDPN32 PGTW 122100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 13W (PEILOU) WARNING 
NR 024//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 30.4N 165.1E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 698 NM NORTHEAST OF MINAMI TORI SHIMA
   MOVEMENT PAST 6 HOURS: EASTWARD AT 13 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TROPICAL
DEPRESSION (TD) 13W (PEILOU) WITH AN EXPOSED LOW LEVEL CIRCULATION
CENTER (LLCC) AND LIMITED CONVECTION CONFINED TO THE EASTERN 
SEMICIRCLE. ENVIRONMENTAL CONDITIONS ARE ASSESSED AS UNFAVORABLE,
WITH MODERATE TO HIGH (20-25 KTS) VERTICAL WIND SHEAR (VWS), MARGINAL 
(26-27 C) SEA SURFACE TEMPERATURES (SSTS), WEAK OUTFLOW ALOFT, AND DRY 
AIR ENTRAINMENT ON THE WESTERN FLANK. THE INITIAL POSITION IS PLACED 
WITH HIGH CONFIDENCE BASED ON THE EXPOSED LLCC. THE INITIAL INTENSITY 
IS ASSESSED WITH MEDIUM CONFIDENCE, BASED ON A WIDER SPREAD OF CIMSS 
OBJECTIVE ESTIMATES AND AGENCY DVORAK FIXES LISTED BELOW.

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

CURRENT STEERING MECHANISM: NEAR-EQUATORIAL RIDGE (NER) CENTERED TO
THE SOUTH

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   RCTP: T2.0 - 30 KTS
   CIMSS ADT: 25 KTS AT 121730Z
   CIMSS AIDT: 31 KTS AT 121730Z
   CIMSS D-MINT: 31 KTS AT 121509Z
   CIMSS D-PRINT: 31 KTS AT 121900Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 20-25 KTS
   SST: 26-27 CELSIUS
   OUTFLOW: WEAK EASTWARD
   OTHER FACTORS: 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 13 IS FORECAST TO CONTINUE NORTHEASTWARD UNDER 
THE STEERING INFLUENCE OF THE NEAR-EQUATORIAL RIDGE (NER) CENTERED TO 
THE SOUTH FOR THE REMAINDER OF THE FORECAST PERIOD. REGARDING 
INTENSITY, THE STRONGEST WINDS ARE EXPECTED TO REMAIN CONFINED TO THE 
SOUTHEASTERN QUADRANT FOR THE REMAINDER OF THE FORECAST PERIOD AND 
EXPERIENCE A GRADUAL WEAKENING TREND. TD 13W IS EXPECTED TO CONTINUE 
INTO AN INCREASINGLY HOSTILE ENVIRONMENT, WITH CONTINUED DRY AIR 
ENTRAINMENT, IMMINENT CROSSING OF THE 26 C ISOTHERM AND WILL SOON BE 
EXPERIENCING OVER 30 KTS OF SHEAR AS IT BECOMES EMBEDDED UNDER STRONG 
UPPER LEVEL WESTERLIES, ULTIMATELY FORECAST TO DISSIPATE BY TAU 36.

MODEL DISCUSSION: TRACK MODEL GUIDANCE IS IN GOOD AGREEMENT FOR THE
REMAINDER OF THE FORECAST PERIOD WITH A CROSS TRACK SPREAD OF 80 NM
AT TAU 36. THE ONLY OUTLIERS OF NAVGEM AND GOOGLE DEEPMIND PREDICT
DISSIPATION OF 13W BY TAU 12, BUT PORTRAY A SIMILAR TRACK. THE
OFFICIAL JTWC TRACK FORECAST IS PLACED WITH HIGH CONFIDENCE, IN
LINE WITH THE MULTI-MODEL CONSENSUS EXCLUDING NAVGEM. INTENSITY
MODEL GUIDANCE IS ALSO IN GOOD AGREEMENT OF A GRADUAL WEAKENING
TREND. THE OFFICIAL JTWC INTENSITY FORECAST IS ASSESSED WITH MEDIUM
CONFIDENCE, BELOW THE MULTI-MODEL CONSENSUS AND DEPICTING DISSIPATION 
SOONER THAN THE BULK OF GUIDANCE AS TD 13W IS NOT EXPECTED TO SURVIVE 
THE DISCUSSED HOSTILE ENVIRONMENT.

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