Tropical Storm PHANFONE Advisory Wed Oct 01

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 18W (PHANFONE) WARNING NR 10//
RMKS//
1. FOR METEOROLOGISTY.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 18W (PHANFONE), LOCATED APPROXIMATELY 503 NM SOUTH-
SOUTHEAST OF IWO TO, HAS TRACKED WESTWARD AT 08 KNOTS OVER THE PAST
SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A
COLD DENSE OVERCAST (CDO) FEATURE WITH TIGHTLY-CURVED BANDING
WRAPPING INTO A RAPIDLY-CONSOLIDATING LOW-LEVEL CIRCULATION CENTER
(LLCC). THE CURRENT POSITION IS BASED ON THE MSI AND A 302341Z ASCAT
PASS WITH HIGH CONFIDENCE. THE INITIAL INTENSITY OF 65 KNOTS IS
BASED ON MATCHING DVORAK INTENSITY FROM PGTW, KNES AND RJTD. UPPER-
LEVEL ANALYSIS INDICATES THE SYSTEM IS LOCATED IN A VERY FAVORABLE
ENVIRONMENT WITH LOW VERTICAL WIND SHEAR AND RADIAL OUTFLOW,
SUPPORTED BY A POINT-SOURCE DIRECTLY OVER THE SYSTEM AND A TUTT CELL
TO THE NORTHEAST. ADDITIONALLY, WARM SEA SURFACE TEMPERATURES IN THE
AREA ARE CONDUCIVE FOR FURTHER DEVELOPMENT. TY 18W IS TRACKING ALONG
THE SOUTHERN PERIPHERY OF A DEEP-LAYERED SUBTROPICAL RIDGE (STR).
3. FORECAST REASONING.
   A. THE FORECAST INTENSITY HAS BEEN CHANGED DUE TO AN INCREASE IN
THE INITIAL INTENSITY AND RAPID INTENSIFICATION OVER THE PAST SIX
HOURS.
   B. TY 18W WILL CONTINUE TRACKING WESTWARD ALONG THE SOUTHERN
PERIPHERY OF THE STR OVER THE NEXT 12 HOURS. A SERIES OF MIGRATORY
TROUGHS PASSING OVER SOUTHERN JAPAN WILL CAUSE A BREAK IN THE STR,
ALLOWING TY 18W TO TURN WEST-NORTHWESTWARD THROUGH TAU 48. UPPER-
LEVEL CONDITIONS ARE EXPECTED TO IMPROVE, ALLOWING TY 18W TO FURTHER
INTENSIFY AND LEADING TO A PEAK INTENSITY OF 125 KNOTS BY TAU 72.
   C. BY TAU 72, TY 18W IS EXPECTED TO ROUND THE RIDGE AXIS AND TURN
NORTHEASTWARD ALONG THE NORTHWESTERN PERIPHERY OF A REBUILDING STR.
BY TAU 96, THE SYSTEM WILL BEGIN EXTRA-TROPICAL TRANSITION AS IT
INTERACTS WITH THE COLD BAROCLINIC ZONE. AVAILABLE MODEL GUIDANCE IS
IN GOOD AGREEMENT IN THE NEAR TERM, BUT BIFURCATES AT THE TURN. GFS
AND ECMWF TRACKERS INDICATE A MORE WESTWARD RECURVATURE IN THE
VICINITY OF KADENA. NAVGEM, HWRF, JENS AND CTCX TRACKERS SHOW A
SOONER RECURVATURE SOUTH OF JAPAN. DUE TO UNCERTAINTY IN THE EXTENT
OF THE STEERING STR AND THE BIFURCATION IN THE LATER TAUS, THERE IS
OVERALL LOW CONFIDENCE IN THE JTWC FORECAST TRACK, WHICH IS
POSITIONED CLOSE TO AND FASTER THAN THE MULTI-MODEL CONSENSUS.//
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