Tropical Storm DOLPHIN Advisory Mon May 18

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 07W (DOLPHIN) WARNING NR 46//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON 07W (DOLPHIN), LOCATED APPROXIMATELY 278 NM SOUTH-
SOUTHWEST OF IWO TO, HAS TRACKED NORTHWARD AT 08 KNOTS OVER THE PAST
SIX HOURS. THE CURRENT POSITION IS BASED ON A 172332Z PGTW SATELLITE
FIX AND A 172236Z SSMIS PASS. THE INTENSITY ESTIMATE OF 110 KNOTS IS
CONSISTENT WITH DVORAK CURRENT INTENSITY ESTIMATES FROM MULTIPLE
REPORTING AGENCIES AS WELL AS RECENT AUTOMATED SATELLITE CONSENSUS
DATA. TY 07W IS ROUNDING THE AXIS OF A SUBTROPICAL STEERING RIDGE.
CONVECTIVE STRUCTURE HAS BEGUN TO DEGRADE OVER THE PAST SIX HOURS AS
THE SYSTEM HAS ENCOUNTERED INCREASING WESTERLY FLOW ALOFT. POLEWARD
UPPER-LEVEL OUTFLOW REMAINS STRONG.
3. FORECAST REASONING.
   A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM
THE PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TY 07W WILL GRADUALLY TURN TOWARD A NORTHEASTWARD TRAJECTORY
OVER THE NEXT 36 HOURS AS IT CONTINUES TO ROUND THE STEERING RIDGE
AXIS. THEREAFTER, THE SYSTEM IS EXPECTED TO ACCELERATE NORTHEASTWARD
AS IT MERGES WITH A DEVELOPING MID-LATITUDE TROUGH AND BECOMES
EXTRATROPICAL. GRADUALLY WEAKENING IS EXPECTED THROUGHOUT THE
FORECAST PERIOD DUE TO INCREASING VERTICAL WIND SHEAR AND DECREASING
ALONG-TRACK SEA SURFACE TEMPERATURES. HOWEVER, FAVORABLE BAROCLINIC
INTERACTION WITH THE APPROACHING TROUGH, OCCURRING AFTER TAU 36 AND
CONTINUING THROUGH TAU 72, SHOULD ALLOW THE SYSTEM TO TRANSITION
INTO A VERY STRONG EXTRATROPICAL LOW. DYNAMIC MODEL GUIDANCE IS IN
VERY GOOD AGREEMENT REGARDING TRACK DIRECTION BUT DIVERGES SLIGHTLY
BY TAU 72 REGARDING TRACK SPEED. OVERALL, THERE IS HIGH CONFIDENCE
IN THE JTWC FORECAST TRACK, WHICH LIES SLIGHTLY AHEAD OF THE MULTI-
MODEL CONSENSUS GIVEN EXPECTATIONS FOR VERY STRONG UPPER-LEVEL
STEERING FLOW.//
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