WDPN32 PGTW 051500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 28W (HALONG) WARNING NR 
005//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 25.2N 142.4E
   INITIAL INTENSITY: 45 KTS
   GEOGRAPHIC REFERENCE: 64 NM EAST-NORTHEAST OF IWO TO
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 03 KTS
   SIGNIFICANT WAVE HEIGHT: 22 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TROPICAL
STORM 28W (HALONG) WITH DEEP BURSTS OF CONVECTION OBSCURING THE
LOW-LEVEL CIRCULATION CENTER (LLCC) AND FRAGMENTED BANDING ALONG
THE EASTERN BOUNDARY. A COMBINATION OF THE 051044Z METOP-B AND 
051132Z METOP-C ASCAT IMAGES REVEALED 40-45 KTS CONFINED TO THE 
NORTHERN SEMICIRCLE OF THE CIRCULATION WITH A MUCH MORE SYMMETRIC 
WIND FIELD COMPARED TO THE PREVIOUS ASCAT PASS 12 HOURS AGO.  THE 
INITIAL INTENSITY, POSITION, AND WIND RADII ARE ALL ASSESSED WITH 
HIGH CONFIDENCE BASED ON THE TIMELY ASCAT IMAGES. PGTW AND KNES FIXES 
OF T3.0 FURTHER SUPPORT THE INITIAL INTENSITY ESTIMATE. ENVIRONMENTAL 
ANALYSIS INDICATES THAT 28W IS IN A FAVORABLE ENVIRONMENT 
CHARACTERIZED BY STRONG POLEWARD AND EASTWARD OUTFLOW, LOW (5-10 KTS) 
VERTICAL WIND SHEAR, AND WARM (29-30 C) SEA SURFACE TEMPERATURES.

INITIAL WIND RADII BASIS: A COMBINATION OF 051044Z AND 051132Z
ASCAT PASSES

CURRENT STEERING MECHANISM: COMPETING STEERING PATTERN WITH
A SUBTROPICAL RIDGE (STR) TO BOTH THE EAST AND WEST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   RJTD: T2.5 - 35 KTS
   KNES: T3.0 - 45 KTS
   CIMSS ADT: 47 KTS AT 051200Z
   CIMSS AIDT: 43 KTS AT 051200Z
   CIMSS D-PRINT: 48 KTS AT 051200Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 10-15 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG POLEWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: HIGH
   INITIAL WIND RADII: HIGH

3. FORECAST REASONING.

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

FORECAST DISCUSSION: 28W IS FORECAST TO INCREASE TRACK SPEEDS OVER
THE NEXT 12 HOURS AND BEGIN TRACKING NORTHWESTWARD, ALONG THE
SOUTHWESTERN PERIPHERY OF THE SUBTROPICAL RIDGE TO THE EAST THROUGH
TAU 48. AROUND TAU 48, 28W IS FORECAST TO BEGIN TURNING NORTHWARD
AS IT ROUNDS THE RIDGE AXIS. NEAR TAU 72, A TURN TO THE NORTHEAST IS 
EXPECTED AS THE SYSTEM TRACKS ALONG THE NORTHWESTERN PERIPHERY OF THE 
RIDGE. TRACK SPEEDS WILL THEN INCREASE AS THE SYSTEM BEGINS TO 
INTERACT WITH THE STRONG MIDLATITUDE WESTERLIES TO THE NORTH. 
EXTRATROPICAL TRANSITION IS NOT EXPECTED TO START WITHIN THE FORECAST 
PERIOD AS THE UPPER-LEVEL FLOW REMAINS ZONAL. THERE IS STILL SOME 
SLIGHT UNCERTAINTY REGARDING THE TIMING AND SHARPNESS OF THE RECURVE, 
BUT MODELS ARE IN MUCH BETTER AGREEMENT ON A RECURVE OCCURRING FAR 
EAST OF THE NORTHERN RYUKYU ISLANDS. REGARDING INTENSITY, 28W IS 
FORECAST TO RAPIDLY INTENSIFY FROM TAU 12 (55 KTS) TO TAU 48 (100 
KTS). A PEAK INTENSITY IS EXPECTED TO OCCUR NEAR TAU 72, AND IS 
CURRENTLY FORECAST TO BE AROUND 120 KTS. THE VORTEX IS EXPECTED TO BE
COMPLETELY ALIGNED IN AROUND 12 HOURS AND THE POLEWARD OUTFLOW
CHANNEL IS EXPECTED TO FURTHER IMPROVE, AIDING IN THE RAPID
INTENSIFICATION (RI). AFTER TAU 72, WESTERLY SHEAR IS EXPECTED TO
QUICKLY INCREASE, CAUSING THE SYSTEM TO WEAKEN THROUGH THE
REMAINDER OF THE FORECAST PERIOD. 

MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE CONTINUES TO BE IN
POOR AGREEMENT, THOUGH IT IS CERTAINLY GETTING BETTER. THE PRIMARY
OUTLIERS ARE NOW NAVGEM AND UKMET. THESE MODELS SHOW A LATER, AND 
SHALLOWER RECURVE, INTERACTING WITH THE NORTHERN RYUKYU ISLANDS AND 
SOUTHERN KYUSHU. THE REMAINDER OF GUIDANCE HAS AN EARLIER RECURVE, 
BEGINNING FAR SOUTHEAST OF KYUSHU. THE ECMWF ENSEMBLE HAS SHIFTED
CONSIDERABLY, NOW SHOWING ALL MEMBERS RECURVING EAST OF OKINAWA.
CROSS-TRACK SPREAD AT TAU 72 IS NOW AROUND 500 NM, BUT WITHOUT
NAVGEM AND UKMET, IT DECREASES TO 350 NM. THE JTWC TRACK FORECAST
IS PLACED IN LINE WITH THE BULK OF RELIABLE GUIDANCE WITH MEDIUM
CONFIDENCE THROUGH TAU 72 AND LOW CONFIDENCE THEREAFTER.  INTENSITY
GUIDANCE IS IN MODERATE AGREEMENT WITH ALL MODELS SHOWING 
INTENSIFICATION THROUGH TAU 72. PEAK INTENSITIES RANGE FROM 90 KTS 
(GFS) TO 135 KTS (COAMPS-TC). THE HAFS-A PEAK HAS RAISED TO AROUND 
130 KTS, MUCH HIGHER COMPARED TO THE PREVIOUS RUN. THE JTWC INTENSITY 
FORECAST IS PLACED SLIGHTLY HIGHER THAN CONSENSUS, CLOSER TO HAFS-A 
AND COAMPS-TC WITH OVERALL MEDIUM CONFIDENCE. 


FORECAST CONFIDENCE:
   TRACK 00-72 HR: LOW
   TRACK 72-120 HR: LOW
   INTENSITY 00-72 HR: MEDIUM
   INTENSITY 72-120 HR: MEDIUM//
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