TS Krosa expected to cross Shikoku within 24hours maintaining a very large wind-field

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WESTERN NORTH PACIFIC

TS KROSA(11W)
As of 06:00 UTC Aug 14, 2019:
Location: 29.4°N 133.1°E
Maximum Winds: 50 kt ( 95km/h)
Gusts: 65 kt (120km/h)
Minimum Central Pressure: 972 mb
WDPN33 PGTW 140900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 11W (KROSA) WARNING NR
035//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM 11W (KROSA), LOCATED APPROXIMATELY 298 NM SOUTH OF
IWAKUNI, JAPAN, HAS TRACKED NORTHWARD AT 05 KNOTS OVER THE PAST SIX
HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS A BROAD
SYSTEM WITH A RAGGED, EXPOSED LOW LEVEL CENTER (LLC) AND A THICK
BAND OF DEEP CONVECTION TO THE SOUTH THAT IS NOW FRAGMENTING. THE
INITIAL POSITION IS BASED ON THE CENTROID OF ROTATION IN THE MSI
IMAGERY WITH FAIR CONFIDENCE, AS THERE ARE ALSO MULTIPLE SMALLER
MESOVORTICES EVIDENT. THE INITIAL INTENSITY OF 50 KNOTS IS HEDGED
SLIGHTLY BELOW THE PGTW AND RJTD DVORAK CURRENT INTENSITY ESTIMATES
OF T3.5 (55 KTS) AND IN CLOSE AGREEMENT WITH A 140357Z SATCON
ESTIMATE OF 53 KTS AND A 140530Z AUTOMATED DVORAK INTENSITY ESTIMATE
OF T3.1 (47 KTS). A 140132Z METOP-B PARTIAL ASCAT PASS SHOWS THE
SYSTEM HAS MAINTAINED AN EXTREMELY BROAD WIND FIELD, WITH BANDS OF
45-49 KT WINDS DISPLACED 80 NM FROM THE CENTER. OBSERVATIONS FROM
130-245NM AWAY ALONG THE JAPANESE COAST REPORT SUSTAINED WINDS
AROUND 30 KTS AND PRESSURES FROM 986-992 MB, DEMONSTRATING THE
EXPANSIVE WIND FIELD; HOWEVER, OTHER COASTAL OBSERVATIONS ARE IN THE
20-30 KT RANGE, AS THE GALE-FORCE WINDS ARE NOT CONTINUOUSLY WRAPPED
AROUND THE SYSTEM. UPPER LEVEL ANALYSIS INDICATES AN OVERALL
MARGINAL ENVIRONMENT WITH AN UPPER LEVEL LOW DIRECTLY OVER THE LLC,
WHICH IS INHIBITING CENTRAL CONVECTION. HOWEVER, UPPER LEVEL OUTFLOW
HAS RECENTLY INCREASED AS TS 11W BEGINS TO TAP INTO AN APPROACHING
MIDLATITUDE TROUGH TO ITS WEST, AND THE EQUATORWARD OUTFLOW CHANNEL
REMAINS EXCELLENT. SEA SURFACE TEMPERATURES (SST) REMAIN CONDUCIVE
(28-29 DEGREES CELSIUS). THE CYCLONE IS TRACKING ALONG THE WESTERN
PERIPHERY OF AN EXTENSION OF THE SUBTROPICAL RIDGE (STR) TO THE
NORTHEAST.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. OVER THE NEXT 24 HOURS, TS 11W WILL CONTINUE ON ITS CURRENT
TRACK AS IT ROUNDS THE WESTERN PERIPHERY OF THE AFOREMENTIONED STR.
NEAR TAU 24, A MIDLATITUDE TROUGH WILL APPROACH FROM THE WEST,
ERODING THE STR AND ALLOWING TS 11W TO RECURVE POLEWARD AROUND THE
STR AXIS. INCREASING POLEWARD OUTFLOW AHEAD OF THE AFOREMENTIONED
TROUGH WILL COMPETE WITH UNFAVORABLE LAND INTERACTION TO MAINTAIN A
45 KT INTENSITY BETWEEN TAU 24 AND 36 AS TS 11W CROSSES OVER SHIKOKU
AND HONSHU. INCREASINGLY UNFAVORABLE (20-30 KNOTS) VERTICAL WIND
SHEAR (VWS) AND COOLER SSTS (22-25 DEGREES CELSIUS) IN THE SEA OF
JAPAN (SOJ) WILL COMBINE TO WEAKEN THE SYSTEM GRADUALLY DOWN TO 35
KNOTS BY TAU 72 AS IT TRACKS THROUGH THE SOJ. MODELS ARE IN FAIR
CROSS-TRACK AGREEMENT, WITH NAVGEM THE EASTERN OUTLIER FEATURING A
TIGHTER RECURVE. THE JTWC FORECAST TRACK IS HEDGED SLIGHTLY WEST OF
THE MULTI-MODEL CONSENSUS TOWARDS THE ECMWF, UKMET, AND GALWEM
SOLUTIONS. THE GFS SOLUTION IS IN LINE WITH, BUT FASTER THAN, THE
MULTI-MODEL CONSENSUS. TS 11W WILL BEGIN EXTRATROPICAL TRANSITION AS
IT INTERACTS WITH THE AFOREMENTIONED TROUGH AND IS EXPECTED TO
BECOME FULLY EXTRATROPICAL AS IT APPROACHES HOKKAIDO NEAR TAU 72.
THERE IS OVERALL HIGH CONFIDENCE IN THE JTWC FORECAST TRACK FOR THIS
PORTION OF THE FORECAST.//
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