Tropical Storm WIPHA Advisory Fri Oct 11

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 25W (WIPHA) WARNING NR
03//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM 25W (WIPHA), LOCATED APPROXIMATELY 674 NM
SOUTH OF IWO TO, HAS TRACKED WESTWARD AT 07 KNOTS OVER THE
PAST SIX HOURS. RECENT ANIMATED INFRARED (IR) SATELLITE IMAGERY
SHOWS DEEP CONVECTION PERSISTING NEAR AN INCREASINGLY DEFINED LOW
LEVEL CIRCULATION CENTER (LLCC) LOCATED JUST WEST OF GUAM. A 102236Z
SSMI-S MICROWAVE IMAGE DEPICTS A PERSISTING BROAD CONVECTIVE BAND
ALONG THE SOUTHERN SEMI-CIRCLE OF THE LLCC. THE POSITION IS BASED ON
RECENT FIXES FROM RJTD AND PGTW AS WELL AS A 102236Z SSMI-S IMAGE.
THE INTENSITY IS ASSESSED AT 40 KNOTS BASED ON DVORAK ESTIMATES FROM
RJTD, KNES, AND PGTW. UPPER LEVEL ANALYSIS INDICATES A FAVORABLE
ENVIRONMENT, WITH LOW TO MODERATE (10 TO 20 KTS) VERTICAL WIND SHEAR
AND DIFFLUENT EASTERLY OUTFLOW, ENHANCED BY A TUTT CELL TO THE
NORTHEAST. TS 25W CONTINUES TRACKING ALONG THE SOUTHWESTERN
PERIPHERY OF THE DEEP-LAYERED SUBTROPICAL RIDGE (STR) TO THE
NORTHEAST.
3. FORECAST REASONING.
   A. MEDIUM-TERM FORECAST INTENSITIES HAVE BEEN ADJUSTED UPWARD
FROM THE PREVIOUS WARNING.
   B. TS 25W IS WILL CONTINUE TRACKING GENERALLY NORTHWESTWARD ALONG
THE SOUTHWESTERN PERIPHERY OF THE STR OVER THE NEXT 72 HOURS,
TURNING POLEWARD LATE IN PERIOD AS A DEVELOPING MID-LATITUDE TROUGH
PASSES TO THE NORTH. HIGH ALONG TRACK OCEAN HEAT CONTENT, LOW
VERTICAL WIND SHEAR, AND FAVORABLE UPPER LEVEL OUTFLOW WILL ALLOW
THE SYSTEM INTENSIFY SIGNIFICANTLY, UP TO AN ESTIMATED PEAK OF 110
KNOTS, BY TAU 72. DYNAMIC MODEL GUIDANCE IS IN GOOD AGREEMENT
THROUGH TAU 72, WITH NAVGEM AND GFDN INDICATING A SLIGHTLY WIDER
RECURVATURE TO THE LEFT OF THE CURRENT FORECAST TRACK. CONFIDENCE IN
THIS PORTION OF THE TRACK FORECAST IS HIGH.
   C. IN THE LATER TAUS, TS 25W IS EXPECTED TO CREST THE STEERING
RIDGE AXIS AND BEGIN RECURVING POLEWARD AHEAD OF THE AFOREMENTIONED
MIDLATITUDE TROUGH. INCREASING VERTICAL WIND SHEAR AND LOWER ALONG-
TRACK SEA SURFACE TEMPERATURES WILL INDUCE STEADY WEAKENING. THE
SYSTEM WILL INTERACT WITH THE MID-LATITUDE TROUGH AND BEGIN
EXTRATROPICAL TRANSITION BY TAU 120. DYNAMIC MODEL GUIDANCE IS IN
FAIR AGREEMENT DURING THIS PORTION OF THE FORECAST, WITH MOST
DISAGREEMENT RELATING TO RECURVATURE TIMING AND POST-RECURVATURE
TRACK SPEED. THE JTWC FORECAST TRACK LIES CLOSE TO THE MULTI-MODEL
CONSENSUS. DUE TO UNCERTAINTY IN THE EXACT TIMING OF RECURVATURE AND
POST-RECURVATURE TRACK SPEED, CONFIDENCE IN THE EXTENDED TRACK
FORECAST IS LOW.//
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