#211 Postby euro6208 » Fri Aug 31, 2018 12:41 am
WDPN31 PGTW 310300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 25W (JEBI) WARNING NR
16//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUPER TYPHOON (STY) 25W (JEBI), LOCATED APPROXIMATELY 443 NM
SOUTH-SOUTHEAST OF IWO TO, JAPAN, HAS TRACKED WESTWARD AT 12 KNOTS
OVER THE PAST SIX HOURS. STY 25W HAS RAPIDLY INTENSIFIED OVER THE
PAST 24 HOURS (45 KNOTS) FROM 100 KNOTS TO THE CURRENT INTENSITY OF
145 KNOTS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS A
COMPACT SYSTEM, APPROXIMATELY 140NM DIAMETER CENTRAL DENSE OVERCAST,
WITH A 15NM ROUND EYE. A 302351Z MHS 89GHZ COLOR COMPOSITE IMAGE
APPEARS TO INDICATE AN INCIPIENT EYEWALL REPLACEMENT CYCLE (ERC)
WITH A SECONDARY EYEWALL FORMING AND A MOAT EVIDENT (AS PREDICTED IN
THE UW-CIMSS P-ERC PRODUCT). THE INITIAL INTENSITY IS ASSESSED AT
145 KNOTS BASED ON PGTW/RJTD DVORAK ESTIMATES OF T7.0 (140 KNOTS)
AND A 302241Z SATCON ESTIMATE OF 150 KNOTS. UPPER-LEVEL ANALYSIS
REVEALS A VERY FAVORABLE ENVIRONMENT WITH LOW VERTICAL WIND SHEAR,
RADIAL OUTFLOW ENHANCED BY A TUTT CELL TO THE EAST, WARM SST (29-
31C) AND HIGH OCEAN HEAT CONTENT VALUES. STY 25W IS TRACKING ALONG
THE SOUTHERN PERIPHERY OF AN EAST-WEST ORIENTED SUBTROPICAL RIDGE
(STR).
3. FORECAST REASONING.
A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY FROM THE
PREVIOUS WARNING.
B. STY 25W WILL CONTINUE TO TRACK WESTWARD TO WEST-NORTHWESTWARD
THROUGH TAU 36 THEN WILL TURN NORTHWESTWARD TO NORTH-NORTHWESTWARD
ALONG THE WESTERN PERIPHERY OF THE STR THROUGH TAU 72. NUMERICAL
MODEL GUIDANCE IS IN GOOD AGREEMENT THROUGH TAU 72 WITH A SPREAD OF
235NM AT TAU 72. BASED ON THE LOW UNCERTAINTY IN THE TRACK GUIDANCE,
CONFIDENCE IN THIS PORTION OF THE JTWC TRACK FORECAST IS HIGH.
ENVIRONMENTAL CONDITIONS ARE FORECAST TO REMAIN VERY FAVORABLE
THROUGH TAU 48, THEREFORE, THE SYSTEM WILL MAINTAIN SUPER TYPHOON
INTENSITY WITH A POTENTIAL PEAK OF 155 KNOTS IN THE NEXT 12 HOURS.
DUE TO THE LIKELIHOOD OF ERC EVENTS OCCURRING, THERE IS SOME
UNCERTAINTY IN THE EXACT JTWC INTENSITY FORECAST OVER THE NEXT FEW
DAYS.
C. AFTER TAU 72, STY 25W WILL ACCELERATE NORTHWARD TO NORTH-
NORTHEASTWARD TOWARD CENTRAL HONSHU AS IT ROUNDS THE STR AXIS. STY
JEBI IS EXPECTED TO BEGIN EXTRA-TROPICAL TRANSITION (ETT) BY TAU 96
AS IT BEGINS TO INTERACT WITH A DEEP MIDLATITUDE SHORTWAVE TROUGH
DIGGING INTO THE KOREAN PENINSULA AND WESTERN JAPAN. STY 25W WILL
RAPIDLY COMPLETE ETT AS IT BECOMES EMBEDDED WITHIN THE MIDLATITUDE
SHORTWAVE TROUGH AND GAINS FRONTAL CHARACTERISTICS OVER THE SEA OF
JAPAN. THE SYSTEM WILL RAPIDLY WEAKEN AFTER TAU 96 DUE TO INCREASING
VERTICAL WIND SHEAR AND INCREASED FRICTIONAL EFFECTS. ADDITIONALLY,
COLD SST VALUES SHOULD CONTRIBUTE TO FURTHER WEAKENING ONCE THE
SYSTEM TRACKS BACK OVER THE SEA OF JAPAN. AFTER COMPLETING ETT, THE
OCCLUDING EXTRA-TROPICAL LOW IS FORECAST TO MAINTAIN STORM-FORCE
WINDS AS IT TRACKS POLEWARD. DUE TO THE INCREASING SPREAD IN THE
NUMERICAL MODEL GUIDANCE ASSOCIATED WITH SIGNIFICANT DIFFERENCES IN
THE TIMING OF THE RECURVE AND TRACK SPEEDS, THERE IS LOW CONFIDENCE
IN THIS PORTION OF THE JTWC FORECAST TRACK.//
NNNN
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Remember, all of my post aren't official. For official warnings and discussions, Please refer to your local NWS products...
NWS for the Western Pacifichttps://www.weather.gov/gum/
