WDPN31 PGTW 022100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 26W (NALGAE) 
WARNING NR 028//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 22.1N 113.8E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 25 NM SOUTHWEST OF HONG KONG
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 10 KTS
   SIGNIFICANT WAVE HEIGHT: 14 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A VERY WEAK
AND INDISTINCT SYSTEM, WHICH IS RAPIDLY WEAKENING. THE LOW LEVEL 
CIRCULATION CENTER (LLCC) IS NOT READILY APPARENT IN THE INFRARED 
IMAGERY, BUT ANIMATED RADAR IMAGERY FROM HONG KONG AND SURFACE OBS
FROM ACROSS THE REGION, PROVIDED ADDITIONAL SUPPORT TO THE INITIAL 
POSITION AND INTENSITY. THE RADAR DATA SUGGESTS THE VERY WEAK ROTATION
IS LOCATED JUST TO THE WEST OF HONG KONG ITSELF. SURFACE OBSERVATIONS
FROM TWO SHIPS LOCATED IN THE HONG KONG ROADSTED WERE REPORTING WINDS 
FROM THE EAST-SOUTHEAST UP TO 36 KNOTS, WHILE CHEUNG CHAU ISLAND 
REPORTED WINDS FROM THE EAST AT 47 KNOTS. PRESSURES WERE REPORTED 
AROUND 1004MB. THE INITIAL INTENSITY IS THUS SET AT 35 KNOTS, WHICH IS
A BIT HIGHER THAN THE AGENCY DVORAK CURRENT INTENSITY ESTIMATES, AND 
IN LINE WITH THE ADT AND AIDT. THE SYSTEM IS MOVING WEST-NORTHWEST
ALONG THE SOUTHERN SIDE OF THE LOW TO MID-LEVEL FLOW ASSOCIATED WITH
A LINGERING COLD SURGE. THE OVERALL ENVIRONMENT IS UNFAVORABLE FOR
TROPICAL CYCLONE DEVELOPMENT, PRIMARILY DUE TO THE INFLUENCE OF LOW
LEVEL DRY AIR INTRUSION FROM THE NORTHEAST, COOL (24-25C) SSTS AND A
LACK OF UPPER-LEVEL OUTFLOW. 

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) TO THE NORTH

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   RJTD: T2.0 - 30 KTS
   KNES: T2.5 - 35 KTS
   CIMSS SATCON: 42 KTS AT 020919Z
   CIMSS ADT: 32 KTS AT 021810Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 5-10 KTS
   SST: 24-25 CELSIUS
   OUTFLOW: WEAK RADIAL

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   INITIAL INTENSITY: MEDIUM
   INITIAL WIND RADII: LOW

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: TS 26W HAS FINALLY TURNED OVER ONTO A MORE WEST-
NORTHWESTWARD TRACK OVER THE PAST SIX HOURS BASED ON ANIMATED RADAR
DATA OUT OF HONG KONG, CURRENTLY PASSING OVER THE SMALL ISLANDS TO THE
WEST OF THE CITY. THE SYSTEM IS EXPECTED TO CONTINUE TO TRACK GENERALLY
WESTWARD OVER THE NEXT 12 HOURS ALONG THE SOUTHERN SIDE OF SOME
REMNANT NORTHEAST SURGE FLOW WHICH IS TRAPPED ALONG THE COAST OF 
SOUTHERN CHINA. AFTER MAKING LANDFALL SHORTLY, TS 26W WILL MOVE DOWN
THE COAST OF SOUTHERN CHINA, ROUGHLY PARALLEL TO THE RUGGED TERRAIN
THAT LIES ALONG TO THE COAST IN THIS REGION. THE SYSTEM WILL STEADILY
WEAKEN AS IT TRACKS OVER THE RUGGED TERRAIN AND IS EXPECTED TO 
DISSIPATE ALONG THE COAST OF SOUTHERN CHINA NO LATER THAN TAU 36, 
THOUGH IT IS POSSIBLE IT WILL REACH ITS DEMISE SOONER, POSSIBLY 
WITHIN THE NEXT 24 HOURS. 


MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT, WITH
ALL TRACKERS SAVE THE NAVGEM, BEING TIGHTLY GROUPED IN A ENVELOPE THAT
TRACKS ALONG THE COAST OF SOUTHEAST CHINA. THE JTWC FORECAST LIES ON
THE NORTHERN EDGE OF THIS ENVELOPE AS A NOD TOWARDS THE RECENT TRACK
MOTION. CONFIDENCE IS MEDIUM, AS IT REMAINS POSSIBLE THAT THE SYSTEM
COULD IN ASSUME THE SOUTHWESTWARD TRACK EARLIER, AND REMAIN OVER WATER
OR BOUNCE BACK AND FORTH ACROSS THE COAST AS IT DRIFTS TO THE
SOUTHWEST. INTENSITY GUIDANCE IS IN GOOD AGREEMENT, WITH ALL GUIDANCE
SUPPORTING THE STEADY WEAKENING TREND AND DISSIPATION WITHIN THE NEXT
24 TO 36 HOURS. 

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: MEDIUM
   INTENSITY 0 - 72 HR: HIGH

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