TS HAGIBIS(20W): developing a microwave eye feature, rapid intensification possible

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WESTERN NORTH PACIFIC

TS HAGIBIS(20W)
As of 06:00 UTC Oct 06, 2019:
Location: 14.2°N 154.1°E
Maximum Winds: 50 kt ( 95km/h)
Gusts: 65 kt ( 120km/h)
Minimum Central Pressure: 996 mb
WDPN31 PGTW 060900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 20W (HAGIBIS)
WARNING NR 005//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 20W (HAGIBIS), LOCATED APPROXIMATELY 537 NM
EAST OF ANDERSEN AFB, GUAM, HAS TRACKED WESTWARD AT 17 KNOTS OVER
THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY SHOWS
THE SYSTEM HAS MAINTAINED TIGHTLY-CURVED DEEP CONVECTIVE BANDING
WRAPPING INTO A FORMATIVE BANDING EYE. THE INITIAL POSITION IS PLACED
WITH HIGH CONFIDENCE BASED ON THE FORMATIVE EYE, THE INITIAL
INTENSITY OF 50KTS IS HEDGED HIGHER THAN AGENCY AND OBJECTIVE DVORAK
ESTIMATES OF T4.0/45KTS TO INDICATE THE INTENSIFICATION AS EVIDENCED
BY THE FORMATIVE EYE. UPPER-LEVEL ANALYSIS INDICATES NEAR-RADIAL
OUTFLOW WITH LOW VERTICAL WIND SHEAR. SST VALUES OF 30-31C AND HIGH
OCEAN HEAT CONTENT VALUES ALSO SUPPORT FURTHER INTENSIFICATION. THE
CYCLONE IS TRACKING ALONG THE SOUTHERN PERIPHERY OF A DEEP-LAYERED
SUBTROPICAL RIDGE (STR) TO THE NORTH.
3. FORECAST REASONING.     
   A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM
THE PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TS 20W IS FORECAST TO TRACK WESTWARD TO WEST-NORTHWESTWARD
THROUGH TAU 72 UNDER THE STEERING INFLUENCE OF THE STR. ENVIRONMENTAL
CONDITIONS ARE EXPECTED TO REMAIN VERY FAVORABLE THROUGH THE FORECAST
PERIOD WITH ROBUST OUTFLOW, WARM SST AND HIGH OCEAN HEAT CONTENT
VALUES SUPPORTING RAPID INTENSIFICATION (RI), REACHING 80KTS IN 24HRS
BEFORE THE SYSTEM HITS THE NORTHERN MARIANAS. AFTERWARD, TS 20W WILL
CROSS INTO THE PHILIPPINE SEA AND CONTINUE WITH RI, REACHING 125KTS
BY TAU 72. NUMERICAL MODELS ARE IN GOOD AGREEMENT WITH A GRADUAL
SPREAD TO 150NM BY TAU 72, LENDING FAIR CONFIDENCE IN THIS PORTION OF
THE JTWC TRACK FORECAST.  
   C. IN THE EXTENDED PERIOD, TS HAGIBIS WILL TRACK MORE
NORTHWESTWARD TOWARD A BREAK IN THE STR ASSOCIATED WITH AN
APPROACHING MIDLATITUDE TROUGH OVER WESTERN JAPAN. IMPROVED POLEWARD
OUTFLOW ASSOCIATED WITH THIS SHORTWAVE TROUGH WILL AID IN BOOSTING
THE INTENSITY TO SUPER TYPHOON STRENGTH. THERE IS INCREASING
UNCERTAINTY AFTER TAU 96 AS THE NUMERICAL MODEL GUIDANCE DIVERGES
WITH A 200 NM SPREAD IN SOLUTIONS AT TAU 120, THEREFORE, THERE IS LOW
CONFIDENCE IN THE EXTENDED PORTION OF THE JTWC TRACK FORECAST.//
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