WDPN31 PGTW 050300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 07W (SEVEN) 
WARNING NR 002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 18.2N 125.3E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 328 NM NORTHEAST OF MANILA, PHILIPPINES
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 22 KTS
   SIGNIFICANT WAVE HEIGHT: 14 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SUGGESTS THAT THE
OVERALL CIRCULATION ASSOCIATED WITH TD 07W HAS IMPROVED SLIGHTLY.
LOW-LEVEL CURVED BANDS ARE NOW CLEARLY EVIDENT IN THE SOUTHERN
SECTOR, WRAPPING INTO A VERY COMPACT LOW LEVEL CIRCULATION CENTER
(LLCC), INDICATING THAT A DISTINCT CLOSED LLCC HAS PINCHED OFF FROM
THE LARGER TROUGH IN WHICH TD 07W WAS PREVIOUSLY EMBEDDED. FROM A
CONVECTIVE STANDPOINT HOWEVER, THE SYSTEM REMAINS DISORGANIZED,
WITH CONVECTION FLARING ALONG THE FEEDER BANDS BUT FAILING TO
MAINTAIN ITSELF OVER OR NEAR THE CORE. THE SYSTEM HAS SPED UP
SIGNIFICANTLY OVER THE PAST FEW HOURS, NO MOVING AT LEAST 22 KNOTS
TOWARDS THE NORTHWEST, ALONG A TIGHTENED GRADIENT ON THE
SOUTHWESTERN PERIPHERY OF A DEEP STR TO THE NORTHEAST. THE INITIAL
POSITION WAS PLACED WITH MODERATE CONFIDENCE INITIALLY BUT LATE
RECEIPT OF A 050023Z ASCAT-A PASS PROVIDES HIGH CONFIDENCE TO THE
POSITION. THE INITIAL INTENSITY IS ASSESSED WITH MODERATE
CONFIDENCE BASED ON A T2.0 (30 KTS) DVORAK INTENSITY ESTIMATE FROM
KNES AND THE PREVIOUSLY MENTIONED ASCAT-A PASS, WHICH DOES SHOW A
SLIGHT FURTHERANCE OF THE WRAP IN THE WIND FIELD IN THE NORTHERN
QUADRANT, AND A PATCH OF 30 KNOT WINDS IN THE NORTHEAST THROUGH
SOUTHEAST QUADRANTS.

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

CURRENT STEERING MECHANISM: DEEP LAYER SUBTROPICAL RIDGE (STR) TO
THE NORTHEAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T1.5 - 25 KTS
   KNES: T2.0 - 30 KTS

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 5-10 KTS
   SST: 30-31 CELSIUS
   OUTFLOW: MODERATE POLEWARD AND EQUATORWARD
   OTHER FACTORS: THE UPPER-LEVEL PATTERN IS VERY COMPLEX, WITH
ANIMATED VISIBLE AND WATER VAPOR IMAGERY PROVIDING CONTRADICTORY
EVIDENCE WHEN COMPARED TO CIMSS UPPER LEVEL WIND ANALYSIS. ANIMATED
WATER VAPOR AND CIRRUS BLOWOFF FROM FLARING CONVECTION INDICATE
NORTHERLY FLOW NOSING IN FAIRLY CLOSE TO THE CORE AND STARTING TO
IMPINGE THE EQUATORWARD OUTFLOW CHANNEL. CIMSS MEANWHILE SHOWS
SOUTHEASTERLY FLOW IN THIS REGION. THE NET RESULT IS ONLY LOW TO
MODERATE EQUATORWARD OUTFLOW FROM THE CORE OF THE SYSTEM ITSELF,
WITH SLIGHTLY BETTER OUTFLOW TOWARDS THE WEST-NORTHWEST INTO AN
UPPER-LEVEL LOW TO THE WEST.  

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: DUE TO THE INCREASE IN FORWARD SPEED
OVER THE PAST FEW HOURS, THE TIME OF LANDFALL HAS MOVED FORWARD
SIGNIFICANTLY AND THE PEAK INTENSITY HAS ALSO BEEN LOWERED 15
KNOTS. 

FORECAST DISCUSSION: TROPICAL DEPRESSION 07W (SEVEN) WILL CONTINUE
RAPIDLY TRACK NORTHWEST THROUGH THE NEXT 12 HOURS ALONG THE
SOUTHWESTERN PERIPHERY OF THE STEERING STR TO THE NORTHEAST.
FORWARD MOTION IS EXPECTED TO REMAIN ABOVE 20 KTS THROUGH TAU 12,
BUT SLOW THEREAFTER AS THE STEERING FLOW SLACKENS AS THE SYSTEM
MOVES SOUTHWEST OF TAIWAN. THE TIMING OF LANDFALL ALONG THE COAST
OF SOUTHEASTERN CHINA HAS MOVED UP SIGNIFICANTLY IN RESPONSE TO THE
FASTER INITIAL MOTION VECTOR, AND IS NOW EXPECTED AT OR BEFORE TAU
36. ENVIRONMENTAL CONDITIONS ARE EXPECTED TO REMAIN MARGINALLY
FAVORABLE FOR CONTINUED DEVELOPMENT THROUGH TAU 24 WITH WARM
(30-31C) SSTS, AND LOW TO MODERATE VWS. HOWEVER THE UPPER-LEVEL
OUTFLOW IS FORECAST TO DEGRADE TO A SINGLE WESTWARD CHANNEL, AND
THE CONTINUED FAST FORWARD MOTION WILL SERVE TO INHIBIT THE
CONSOLIDATION AND EXPANSION OF THE CORE ON THE WESTERN SIDE. THUS
TD 07W IS FORECAST TO CONTINUE TO INTENSIFY BUT AT A MUCH SLOWER
RATE THAN THE PREVIOUS FORECAST, WITH A PEAK OF 40 KTS NOW EXPECTED
AROUND TAU 24. ONCE INLAND OVER SOUTHEASTERN CHINA, THE SYSTEM WILL
RAPIDLY WEAKEN AND DISSIPATE BY TAU 48. 

MODEL DISCUSSION: NUMBERICAL MODEL GUIDANCE REMAINS GOOD AGREEMENT
ON THE OVERALL SCENARIO BUT SHOWS INCREASED UNCERTAINY COMPARED
WITH THE PREVIOUS FORECAST. THE HWRF AND NAVGEM REMAIN THE RIGHT
SIDE (DOWN TRACK) OUTLIERS, TAKING THE SYSTEM OVER TAIWAN, WHILE
THE ECMWF AND ECMWF ENSEMBLE ARE THE LEFTMOST OUTLIERS. SPREAD
BETWEEN OUTLIERS IS 150 NM AT TAU 24 INCREASING TO 285 NM BY TAU
36. THE STRENGTHENING OF THE LOW TO MID-LEVEL RIDGE INTO CENTRAL
CHINA AFTER TAU 12 SHOULD RESULT IN A SLIGHTLY MORE WESTWARD TRACK,
WHICH IS REFLECTED IN THE OFFICIAL FORECAST. THE NVGM AND HWRF
SOLUTIONS TAKE THE SYSTEM UNREALISTICALLY INTO THE TEETH OF THE
RIDGE TO THE NORTH AND ARE DEEMED UNLIKELY SOLUTIONS. THE JTWC
FORECAST LIES ON THE RIGHT EDGE OF THE TIGHTEST GROUPING OF THE
CONSENSUS MEMBERS THROUGH LANDFALL. INTENSITY GUIDANCE HAS SHIFTED
DRAMATICALLY DOWNWARD SINCE THE PREVIOUS FORECAST, WITH ALL
AVAILABLE GUIDANCE MAINTAINING PEAK INTENSITY AT OR BELOW 40 KNOTS.
THE JTWC FORECAST REMAINS ABOVE THE INTENSITY CONSENSUS AND NEAR
THE GFS SOLUTION.  

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