Tropical Storm YUTU Advisory Fri Oct 26

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 31W (YUTU) WARNING NR
19//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   SUPER TYPHOON (STY) 31W (YUTU), LOCATED APPROXIMATELY 903 NM
SOUTHEAST OF KADENA AB, OKINAWA, JAPAN, HAS TRACKED WEST-
NORTHWESTWARD AT 11 KNOTS OVER THE PAST SIX HOURS. ANIMATED
MULTISPECTRAL SATELLITE IMAGERY DEPICTS A CONSOLIDATING, SYMMETRIC
EYEWALL SURROUNDING AN OBLONG EYE. ADDITIONALLY, A 260033Z AMSU
89GHZ IMAGE REVEALS A 40NM MICROWAVE EYE FEATURE, THEREFORE, THERE
IS GOOD CONFIDENCE IN THE INITIAL POSITION. HOWEVER, RECENT ANIMATED
SATELLITE IMAGERY CONTINUES TO INDICATE TROCHOIDAL TRACK MOTION.
UPPER-LEVEL ANALYSIS INDICATES A FAVORABLE ENVIRONMENT WITH LOW (10
TO 15 KNOTS) EASTERLY VERTICAL WIND SHEAR AND ROBUST OUTFLOW WITH
THE EXCEPTION OF THE EASTERN QUADRANT. THE INITIAL INTENSITY IS HELD
AT SUPER TYPHOON STRENGTH (130 KNOTS) BASED ON A PGTW DVORAK CURRENT
INTENSITY ESTIMATE OF 127 KNOTS, CONSISTENT WITH A 252137Z SATCON
ESTIMATE OF 128 KNOTS. STY 31W IS TRACKING WEST-NORTHWESTWARD ALONG
THE SOUTHWEST PERIPHERY OF A DEEP SUBTROPICAL RIDGE (STR) POSITIONED
TO THE NORTHEAST WITH A BREAK IN THE STR LOCATED SOUTH OF HONSHU
(NORTH OF THE SYSTEM) ASSOCIATED WITH A BROAD, WEAK MIDLATITUDE
SHORTWAVE TROUGH.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. STY 31W IS FORECAST TO CONTINUE TRACKING WEST-NORTHWESTWARD
TOWARD THE BREAK IN THE STR THROUGH TAU 36, HOWEVER, THE SYSTEM
SHOULD GRADUALLY TURN MORE WESTWARD AFTER TAU 36 AS THE
AFOREMENTIONED SHORTWAVE TROUGH PROPAGATES EASTWARD AND A BROAD
MIDLATITUDE RIDGE TO THE NORTH ALLOWS THE STR TO RE-BUILD. EXCLUDING
THE PRIMARY OUTLIERS, COAMPS-TC (CTCX) AND NAVGEM, DYNAMIC MODEL
GUIDANCE IS IN BETTER AGREEMENT THROUGH TAU 72 WITH A 170NM SPREAD
IN SOLUTIONS AT TAU 72. STY 31W IS EXPECTED TO MAINTAIN NEAR-STY
STRENGTH THROUGH TAU 12 AS THE EYEWALL RE-STRENGTHENS AND THE EYE
CONTRACTS. HOWEVER, AFTER TAU 12, THE SYSTEM SHOULD GRADUALLY WEAKEN
AS VERTICAL WIND SHEAR INCREASES TO MODERATE LEVELS.
   C. BEYOND TAU 72, THERE IS INCREASING UNCERTAINTY IN THE FORECAST
TRACK WITH TWO DISTINCT CLUSTERS OF MODEL GUIDANCE. ECMWF, EEMN,
UKMET, JGSM, AFUM, GFS, AEMN AND HWRF INDICATE A WEST-SOUTHWESTWARD
(OVER LUZON) TO WEST-NORTHWESTWARD (TOWARD THE LUZON STRAIT) TRACK.
NAVGEM AND COAMPS-TC (CTCX) CONTINUE TO INDICATE AN UNLIKELY RECURVE
SCENARIO. BASED ON ANALYSIS OF MODEL FIELDS FROM BOTH CLUSTERS, THE
RE-CURVE SCENARIO IS ASSESSED AS UNLIKELY DUE TO A LACK OF A DEEP
MIDLATITUDE SHORTWAVE TROUGH AND THE PRESENCE OF A LOW-LEVEL RIDGE
FORECAST TO BUILD OVER THE EAST CHINA SEA. THE JTWC FORECAST TRACK
FAVORS A MORE WESTWARD TRACK WITH A DECREASE IN TRACK SPEEDS
ASSOCIATED WITH A BREAK IN THE STR AND INCREASING NORTHEASTERLY LOW-
LEVEL FLOW FORECAST TO DEVELOP EAST OF TAIWAN. BASED ON THE
BIFURCATION IN THE DYNAMIC MODELS AND LARGE OVERALL SPREAD, THERE IS
LOW CONFIDENCE IN THIS PORTION OF THE JTWC FORECAST TRACK.//
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