Tropical Storm DOLPHIN Advisory mar, 19-05

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 07W (DOLPHIN) WARNING NR 50//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 07W (DOLPHIN), LOCATED APPROXIMATELY 124 NM WEST-
SOUTHWEST OF IWO TO, JAPAN HAS TRACKED NORTHEASTWARD AT
08 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED MULTISPECTRAL
SATELLITE IMAGERY DEPICTS WEAK CONVECTION OVER A TIGHTLY WRAPPED LOW
LEVEL CIRCULATION CENTER (LLCC). AN 182222Z SSMIS 91GHZ MICROWAVE
IMAGE REVEALS AN EXPOSED LLCC WITH THE ONLY REMAINING DEEP
CONVECTION ALONG THE NORTHERN PERIPHERY. THE INITIAL POSITION IS
BASED ON THE EXPOSED LLCC IN THE SSMIS MICROWAVE IMAGE WITH GOOD
CONFIDENCE. THE INITIAL INTENSITY HAS BEEN LOWERED TO 75 KNOTS BASED
ON AN ASSESSMENT OF DECREASING CURRENT INTENSITY ESTIMATES FROM
RJTD, KNES, AND PGTW. UPPER LEVEL ANALYSIS SHOWS AN EXTENSION OF THE
MID-LATITUDE WESTERLIES HAS WRAPPED COMPLETELY AROUND THE SYSTEM,
INTEGRATING DRY AIR INTO THE CIRCULATION AND DISSIPATING CONVECTION.
IN ADDITION, TY 07W IS BEING IMPACTED BY LOW TO MODERATE (15-20
KNOT) SOUTHWESTERLY VERTICAL WIND SHEAR (VWS). TY DOLPHIN CONTINUES
TO TRACK ALONG THE NORTHWESTERN PERIPHERY OF A DEEP LAYER SUB-
TROPICAL RIDGE TO THE SOUTHEAST.
3. FORECAST REASONING.
   A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM
THE PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TY DOLPHIN WILL CONTINUE TO ACCELERATE NORTHEASTWARD, DEEPER
INTO THE MID-LATITUDE WESTERLIES WHERE IT WILL ENCOUNTER HIGH VWS
AND SEA SURFACE TEMPERATURES RAPIDLY DECREASING BELOW 26 CELSIUS. TY
07W WILL BEGIN EXTRA-TROPICAL TRANSITION (ETT) NEAR TAU 24 AND IS
EXPECTED TO COMPLETE ETT BY THE END OF THE FORECAST PERIOD AS A
STRONG COLD CORE LOW. THERE IS HIGH CONFIDENCE IN THE JTWC FORECAST
TRACK AS MODEL GUIDANCE REMAINS IN VERY TIGHT AGREEMENT.//
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