WDPN31 PGTW 040900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 27W (MATMO) WARNING NR 
013//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 18.2N 115.2E
   INITIAL INTENSITY: 60 KTS
   GEOGRAPHIC REFERENCE: 252 NM SOUTH-SOUTHEAST OF HONG KONG
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 15 KTS
   SIGNIFICANT WAVE HEIGHT: 28 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL
STORM 27W (MATMO) WITH IMPROVING CONVECTIVE BANDING WRAPPING AROUND
THE LOW-LEVEL CIRCULATION CENTER (LLCC). CLOUD TOPS HAVE COOLED
OVER THE PAST 6 HOURS, PARTICULARLY WITHIN DEEP BURSTS OF
CONVECTION IN THE SOUTHEASTERN QUADRANT. A 040223Z METOP-C ASCAT
IMAGE REVEALED 40-45 KTS WITHIN THE EASTERN SEMICIRCLE. APPEARANCE
HAS IMPROVED SINCE THE IMAGE, AND COMBINED WITH THE LOW BIAS OF
ASCAT, THE INITIAL INTENSITY OF 60 KTS IS ASSESSED WITH MEDIUM
CONFIDENCE. ADDITIONALLY, AGENCY DVORAK FIXES OF T3.5-4.0 FURTHER
SUPPORT THE INITIAL INTENSITY ASSESSMENT. THE INITIAL POSITION IS
PLACED WITH HIGH CONFIDENCE BASED ON THE ANIMATED MSI AND
EXTRAPOLATION FROM THE AFOREMENTIONED ASCAT IMAGE. ENVIRONMENTAL
ANALYSIS INDICATES THAT 27W IS IN A HIGHLY FAVORABLE ENVIRONMENT
CHARACTERIZED BY STRONG RADIAL OUTFLOW ALOFT, LOW (5-10 KTS)
VERTICAL WIND SHEAR, AND WARM (29-30 C) SEA SURFACE TEMPERATURES.

INITIAL WIND RADII BASIS: PERSISTENCE FROM THE 040223Z METOP-C
ASCAT PASS

CURRENT STEERING MECHANISM: SOUTHWESTERN PERIPHERY OF A
DEEP-LAYERED SUBTROPICAL RIDGE (STR) POSITIONED TO THE NORTHEAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.0 - 65 KTS
   RJTD: T3.5 - 55 KTS
   RCTP: T4.0 - 65 KTS
   KNES: T4.0 - 65 KTS
   DEMS: T4.0 - 65 KTS
   CIMSS SATCON: 61 KTS AT 040600Z
   CIMSS ADT: 47 KTS AT 040600Z
   CIMSS AIDT: 40 KTS AT 040600Z
   CIMSS D-MINT: 57 KTS AT 040506Z
   CIMSS D-PRINT: 53 KTS AT 040600Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE
   VWS: 5-10 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG RADIAL

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: 27W IS FORECAST TO TRACK NORTHWESTWARD, ALONG
THE SOUTHWESTERN PERIPHERY OF THE SUBTROPICAL RIDGE THROUGHOUT THE
FORECAST PERIOD. AN INITIAL LANDFALL IS FORECAST TO OCCUR ALONG THE
SOUTHERN LEIZHOU PENINSULA NEAR TAU 24. THE SYSTEM IS THEN FORECAST
TO BRIEFLY EMERGE WITHIN THE GULF OF TONKIN BEFORE MAKING A SECOND
LANDFALL JUST EAST OF THE VIETNAM-CHINA BORDER AROUND TAU 36.
REGARDING INTENSITY, 27W IS FORECAST TO NEAR-RAPIDLY INTENSIFY OVER
THE NEXT 24 HOURS AS THE SYSTEM REMAINS IN A HIGHLY FAVORABLE
ENVIRONMENT. THE PEAK INTENSITY WILL LIKELY OCCUR AROUND TAU 18,
WHICH IS NOT ABLE TO BE CAPTURED BY THE FORECAST. AFTER TAU 24,
LAND INTERACTION WITH SOUTHERN CHINA WILL DETERIORATE THE VORTEX.
AFTER MAKING ITS FINAL LANDFALL, 27W WILL RAPIDLY WEAKEN AND THE
REMNANT VORTEX WILL LIKELY FULLY DISSIPATE NO LATER THAN TAU 72,
NORTH OF VIETNAM AND LAOS.

MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE IS IN VERY GOOD
AGREEMENT THROUGHOUT THE ENTIRE FORECAST WITH A MERE 52 NM
CROSS-TRACK SPREAD AT TAU 48. AS A RESULT, THE JTWC TRACK FORECAST
IS PLACED CLOSE TO THE MULTI-MODEL CONSENSUS WITH HIGH CONFIDENCE.
INTENSITY GUIDANCE IS IN MODERATE AGREEMENT WITH ALL MODELS
DEPICTING INTENSIFICATION THROUGH THE INITIAL LANDFALL AND WEAKENING
THEREAFTER. THE JTWC INTENSITY FORECAST IS PLACED SLIGHTLY HIGHER
THAN CONSENSUS THROUGH TAU 24, AND THEN IN LINE WITH CONSENSUS
AFTERWARD WITH MEDIUM CONFIDENCE.

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