WDPN32 PGTW 122100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 07W (SEVEN) WARNING 
NR 001//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 30.8N 123.6E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 340 NM WEST-SOUTHWEST OF SASEBO, JAPAN
   MOVEMENT PAST 6 HOURS: EAST-NORTHEASTWARD AT 07 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A
ELONGATED AND BROAD SUBTROPICAL DEPRESSION WITH CONVECTION PULSING
POLEWARD AND EASTWARD OF THE CIRCULATION CENTER. WATER VAPOR
IMAGERY HIGHLIGHTS THE UPPER-LEVEL CYCLONE PRESENT OVER THE
LOW-LEVEL CIRCULATION CENTER (LLCC). THE INITIAL POSITION IS PLACED
WITH HIGH CONFIDENCE BASED ON THE AFOREMENTIONED ANIMATED EIR. THE
INITIAL INTENSITY OF 30 KTS IS ASSESSED WITH MEDIUM CONFIDENCE
BASED ON 121529Z OCEANSAT-3 OSCAT SCATTEROMETRY HIGHLIGHTING THE
IRREGULARLY SHAPED AND ELONGATED LOW-LEVEL CIRCULATION WITH
25-30KTS IN THE SOUTHWESTERN PERIPHERY.

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

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T1.5 - 25 KTS
   RJTD: T1.0 - 25 KTS

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 10-15 KTS
   SST: 25-26 CELSIUS
   OUTFLOW: WEAK POLEWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: LOW
   INITIAL WIND RADII: NOT APPLICABLE

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THIS INITIAL PROGNOSTIC REASONING
MESSAGE ESTABLISHES THE FORECAST PHILOSOPHY.

FORECAST DISCUSSION: SUBTROPICAL DEPRESSION (SD) 07W IS FORECAST TO
TRACK EAST-NORTHEASTWARD FOR THE NEXT 12 HOURS. A LONGWAVE
UPPER-LEVEL TROUGH WILL CAUSE THE LOW TO DEEPEN, AND CURVE
NORTHWARD FROM TAU 24-36. BETWEEN TAU 36-72, THE SUBTROPICAL
DEPRESSION IS ANTICIPATED TO CURVE NORTHWESTWARD AS THE LOW
CONTINUES TO DEEPEN. THE CONFIDENCE OF SUBTROPICAL DEPRESSION 07W
TO DEVELOP INTO A TROPICAL CYCLONE IS ASSESSED AS LOW AT THIS TIME
AS THE SYSTEM IS ANTICIPATED TO REMAIN EMBEDDED WITHIN A DEEP-LAYER
CYCLONE AND SEA SURFACE TEMPERATURES WILL BE COOL AS THE SYSTEM
PASSES INTO THE SEA OF JAPAN. BAROCLINIC FORCING IS ANTICIPATED TO
CAUSE GRADUAL INTENSIFICATION TO A PEAK OF 40KTS WITHIN THE FIRST
24 HOURS OF THE FORECAST, FOLLOWED BY GRADUAL WEAKENING BETWEEN TAU
36-72 DUE TO TOPOGRAPHIC INTERACTION WITH THE KOREAN PENINSULA.

MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE IS IN GENERAL
AGREEMENT AND HAS A LARGE SPREAD OF MODEL SOLUTIONS. THE CURRENT
FORECAST LIES WITH THE BULK OF THE CONSENSUS MEMBERS, WITH THE
ECMWF ENSEMBLE OUTLYING TO THE EAST WITH A NEARLY NORTHEASTWARD
TRACK. THE ENSEMBLE GUIDANCE IS SPREAD BETWEEN GEFS AND ECENS, WITH
JUST UNDER HALF OF THE ENSEMBLE MEMBERS OF BOTH MODELS LYING SOUTH
OF THE CURRENT FORECAST TRACK. THE INTENSITY GUIDANCE IS SPREAD
BETWEEN A PEAK OF 35-40KTS, HOWEVER A TRACK OVER WATER MAY ALLOW
FOR STRONGER INTENSIFICATION RATHER THAN THE PEAK REPRESENTED IN
THE CURRENT FORECAST OVER LAND.

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