Advisories

WDPN32 PGTW 050300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 13W (KUJIRA) WARNING 
NR 002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 17.6N 118.7E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 224 NM NORTHWEST OF MANILA, PHILIPPINES
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 02 KTS
   SIGNIFICANT WAVE HEIGHT: 10 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS THE ELONGATED, 
EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC) OF TROPICAL DEPRESSION 
(TD) 13W (KUJIRA) WITH DEEP CONVECTION REMAINING SHEARED TO THE 
SOUTHWEST. A 042204Z 37 GHZ SSMIS MICROWAVE IMAGE DEPICTS TD 13W WITH 
SHALLOW LOW LEVEL CLOUD BANDING TO THE NORTH AND DISORGANIZED 
CONVECTION TO THE SOUTHWEST. THE INITIAL POSITION IS PLACED WITH HIGH 
CONFIDENCE BASED ON THE EXPOSED LLCC. THE INITIAL INTENSITY IS 
ASSESSED WITH HIGH CONFIDENCE BASED ON THE GENERAL AGREEMENT OF AGENCY 
DVORAK FIXES OF T2.0, CONSISTENT WITH THE MOST RECENT SCATTEROMETER 
DATA AND CIMSS OBJECTIVE ESTIMATES LISTED BELOW.

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

CURRENT STEERING MECHANISM: WEAK STEERING ENVIRONMENT DOMINATED BY
LOW-LEVEL SOUTHWESTERLY MONSOON FLOW 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   RJTD: T2.0 - 30 KTS
   RCTP: T2.0 - 30 KTS
   KNES: T1.5 - 25 KTS
   CIMSS ADT: 31 KTS AT 050000Z
   CIMSS AIDT: 27 KTS AT 05000Z
   CIMSS D-MINT: 27 KTS AT 042204Z
   CIMSS D-PRINT: 28 KTS AT 042340Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY
UNFAVORABLE
   VWS: 15-20 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: WEAK EQUATORWARD

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: TD 13W IS EXPECTED TO BE QUASI-STATIONARY FOR
THE NEXT 6 HOURS BEFORE BEGINNING AN EASTWARD TURN AND INCREASE IN
TRACK SPEED. THIS WILL OCCUR DUE TO THE WESTWARD ADVANCE OF TY 12W
AND SUBSEQUENT STRENGTHENING OF THE LOW LEVEL WESTERLIES AROUND LUZON 
AS THEY APPROACH THE SOUTHWEST INFLOW REGION OF TY DOLPHIN. IN REGARDS 
TO INTENSITY, THE SYSTEM IS FORECAST TO INTENSIFY SLIGHTLY TO 35 KTS 
BEFORE MAKING LANDFALL NEAR VIGAN BETWEEN TAUS 12 AND 24, WHICH WILL 
CAUSE A SHARP WEAKENING TREND DUE TO THE INTERACTION WITH THE 
MOUNTAINOUS TERRAIN OF NORTHERN LUZON. THERE IS SOME UNCERTAINTY AS TO 
WHETHER TD 13W WILL MAINTAIN A STRONG ENOUGH VORTEX TO REEMERGE BACK 
OVER WATER ON THE EASTERN COAST OF LUZON, BUT THIS IS ASSESSED AS 
UNLIKELY DUE TO THE WEAK NATURE OF THE SYSTEM AND STRONGLY CONVERGENT 
SOUTHWESTERLY INFLOW.

MODEL DISCUSSION: MODEL GUIDANCE IS GENERALLY IN GOOD AGREEMENT IN
TERMS OF AN EASTWARD DIRECTION OF TD 13W OVER LUZON, WITH A CROSS
TRACK SPREAD OF 55 NM AT TAU 36, EXCLUDING THE OUTLIER OF GALWEM.
PREDICTED TRACK SPEED DIFFERS MUCH MORE, WITH AN ALONG TRACK SPREAD
OF 400 NM DUE TO SOME MODELS NOT PREDICTING TD 13W TO BE PICKED UP
BY THE STRONGER LOW LEVEL WESTERLIES. THE OFFICIAL JTWC FORECAST IS
PLACED WITH MEDIUM CONFIDENCE CLOSELY IN LINE WITH THE MULTI-MODEL
CONSENSUS BUT SLIGHTLY SLOWER IN TRACK SPEED, IN LINE WITH THE AI
CONSENSUS. INTENSITY GUIDANCE IS IN GOOD AGREEMENT OF A SHARP
DECLINE OF INTENSITY ONCE 13W MAKES LANDFALL, SO THE OFFICIAL JTWC
INTENSITY FORECAST IS ASSESSED WITH MEDIUM CONFIDENCE, SLIGHTLY ABOVE 
THE MULTI-MODEL CONSENSUS.

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