Tropical Storm KIROGI Advisory Thu Aug 09

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 13W (KIROGI)
WARNING NR 18//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION 13W (KIROGI), LOCATED APPROXIMATELY 745 NM
EAST-SOUTHEAST OF MISAWA, JAPAN, HAS TRACKED NORTHWESTWARD AT 14
KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY AND A 082149Z SSMIS 91 GHZ MICROWAVE IMAGE DEPICT A SLIGHTLY
ELONGATED LOW LEVEL CIRCULATION CENTER (LLCC) ORIENTED FROM NW TO SE
WITH A SMALL AREA OF CONVECTION OVER THE SOUTHERN SEMI-CIRCLE. A
PARTIAL 082244Z ASCAT SATELLITE IMAGE INDICATES WINDS ALONG THE
EASTERN PERIPHERY ARE BETWEEN 25 TO 30 KNOTS. THE MOST RECENT AMSU
CROSS-SECTION (081500Z) SHOWS THE +2 DEGREE CELSIUS WARM-CORE
ANOMALY REMAINS PERSISTENT NEAR 10 TO 11 KM. THE CURRENT INTENSITY
OF 30 KNOTS IS BASED ON THE ASCAT PASS AND A RANGE OF DVORAK
ESTIMATES FROM 25 TO 35 KNOTS FROM PGTW, RJTD, AND KNES. UPPER-LEVEL
ANALYSIS INDICATES THAT TD 13W IS LOCATED SOUTH OF THE SUBTROPICAL
RIDGE (STR) AXIS WITH A TROPICAL UPPER TROPOSPHERIC TROUGH (TUTT)
CELL TO THE SOUTH. VERTICAL WIND SHEAR IS CURRENTLY AT 10-15 KNOTS,
AND UPPER-LEVEL DIVERGENCE IS MINIMAL WITH VERY WEAK OUTFLOW TO THE
SOUTH INTO THE TUTT. RECENT ANIMATED WATER VAPOR IMAGERY CONTINUES
TO SHOW A NARROW REGION OF POLEWARD OUTFLOW AS TD 13W TRACKS CLOSER
TO AN UPPER-LEVEL SHORTWAVE TROUGH EAST OF JAPAN. TOTAL PRECIPITABLE
WATER IMAGERY INDICATES THE SYSTEM IS BECOMING ELONGATED AND REMAINS
CUT-OFF FROM ANY CONNECTION TO THE MARITIME TROPICAL AIR MASS.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
   B. TD 13W IS EXPECTED TO TRACK UNDER THE SOUTHWESTERN PERIPHERY
OF THE STR, POSITIONED TO THE EAST, FOR THE REMAINDER OF THE
FORECAST PERIOD. THE SYSTEM IS FORECAST TO TRACK OVER INCREASINGLY
COOLER SEA SURFACE TEMPERATURES (SST) (< 25 CELSIUS) AT 38 DEGREES
NORTH, AFTER TAU 12, AND WILL BEGIN TO INTERACT WITH THE EASTERN
PERIPHERY OF A SHORTWAVE TROUGH THAT IS EXPECTED TO DEEPEN EAST OF
JAPAN. QUICKLY DECREASING SSTS WILL CAUSE A TRANSITION FROM WARM-
CORE TROPICAL TO A COLD-CORE SUBTROPICAL LOW. ALTHOUGH THE FORECAST
CONFIDENCE FOR THE TIMING OF SUBTROPICAL TRANSITION IS LOW, THE
TRACK FORECAST CONFIDENCE REMAINS HIGH DUE TO TIGHTLY CLUSTERED
OBJECTIVE AID GUIDANCE.//
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