Tropical Storm YUTU Advisory Thu Oct 25

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 31W (YUTU) WARNING NR
15//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   SUPER TYPHOON (STY) 31W (YUTU), LOCATED APPROXIMATELY 99 NM
WEST-NORTHWEST OF SAIPAN, HAS TRACKED WEST-NORTHWESTWARD AT 12 KNOTS
OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY
SHOWS STY 31W HAS MAINTAINED A WELL DEFINED EYE WITH DEEP CONVECTION
SURROUNDING IT. THE INITIAL POSITION IS BASED ON A 250000Z HIMAWARI
VISIBLE SATELLITE IMAGE WHICH SHOWS THE 20NM WIDE EYE. THE INITIAL
INTENSITY OF 145 KNOTS IS BASED ON A SLIGHT WEAKENING TREND DUE TO AN
EYEWALL REPLACEMENT CYCLE AND IS HEDGED BETWEEN DVORAK CURRENT
INTENSITY (CI) ESTIMATES OF T7.5 (155 KNOTS) FROM PGTW, RJTD, AND
KNES, AND AN ADT CI OF T7.0 (140 KNOTS). ENVIRONMENTAL ANALYSIS SHOWS
STY 31W IS EXPERIENCING MODERATE VERTICAL WIND SHEAR (15 TO 20 KNOTS)
AND HAS NEAR RADIAL OUTFLOW. SEA SURFACE TEMPERATURES ALSO REMAIN
FAVORABLE, NEAR 30 DEGREES CELSIUS. STY 31W IS TRACKING ALONG THE
SOUTHWESTERN PERIPHERY OF A SUBTROPICAL RIDGE (STR) LOCATED TO THE
NORTHEAST AND THE SOUTHEASTERN PERIPHERY OF AN STR LOCATED TO THE
NORTHWEST.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. THROUGH TAU 72, STY 31W WILL CONTINUE TO TRACK TO THE
WEST-NORTHWEST WHILE POSITIONED BETWEEN THE AFOREMENTIONED STRS.
MODEL GUIDANCE REMAINS IN FAIRLY GOOD AGREEMENT THOUGH TAU 24,
INDICATING A WEST-NORTHWESTWARD TRACK, BUT QUICKLY DIVERGES AFTER
THAT WITH A SPREAD OF 470 NM BY TAU 72. AT TAU 72, JGSM IS THE
OUTLIER TO THE SOUTHWEST INDICATING A WESTWARD TRACK WITH NVGM THE
OUTLIER TO THE NORTHEAST INDICATING A RECURVE SCENARIO. THE JTWC
FORECAST TRACK IS PLACED NEAR THE MULTI-MODEL CONSENSUS IN THE MIDDLE
GROUP OF A TRIFURCATION, FAVORING THE ECMWF, HWRF, AND GFS TRACKERS.
DUE TO THE WIDE SPREAD IN MODEL GUIDANCE THERE IS LOW CONFIDENCE IN
THIS PORTION OF THE JTWC FORECAST TRACK.
   C. BEYOND TAU 72, THE TRIFURCATION IN THE MODELS BECOMES EVEN MORE
PRONOUNCED. JGSM, EGRR, AND AFUM INDICATE A WEST-SOUTHWESTWARD TRACK
WITH NVGM AND CTCX INDICATING A NORTHEASTWARD TRACK. ECMWF, GFS, AND
HWRF INDICATE A WEST-NORTHWESTWARD TRACK AND A DECREASE IN FORWARD
SPEED NEAR TAU 96. NVGM AND JGSM REMAIN AT THE EDGES OF THE MODEL
ENVELOPE AND HAVE A MASSIVE SPREAD OF 2010 NM BY TAU 120. THE JTWC
FORECAST TRACK IS PLACED NEAR THE MULTI-MODEL CONSENSUS, FAVORING THE
GFS, HWRF AND ECMWF SOLUTIONS. DUE TO THE WIDE SPREAD IN MODEL
GUIDANCE THERE IS LOW CONFIDENCE IN THIS PORTION OF THE JTWC FORECAST
TRACK.//
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