Tropical Storm DAMREY Advisory Wed Aug 01

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 11W (DAMREY) WARNING NR
14//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM 11W (DAMREY), LOCATED APPROXIMATELY 240 NM
SOUTHEAST OF SASEBO, JAPAN, HAS TRACKED WEST-NORTHWESTWARD AT 20
KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY (MSI) SHOWS THE FAST MOVING, WELL-DEFINED, LOW LEVEL
CIRCULATION CENTER (LLCC) HAS BEEN MAINTAINING A STEADY TRACK
TOWARDS SOUTHERN KYUSHU FOR THE PAST 12 HOURS. DEEP CONVECTION HAS
NOW COMPLETELY WRAPPED AROUND THE LLCC ALONG THE NORTHERN PERIPHERY.
RADAR IMAGERY FROM KYUSHU CLEARLY SHOWS THE LLCC AND ASSOCIATED RAIN
BANDS. THE CURRENT INTENSITY OF 60 KNOTS IS BASED ON THE RECENT
INCREASE IN DVORAK ESTIMATES FROM PGTW WHICH IS NOW IN LINE WITH THE
DVORAK ESTIMATE FROM RJTD. UPPER LEVEL ANALYSIS INDICATES THE
POLEWARD OUTFLOW CHANNEL REMAINS THE PRIMARY VENTING MECHANISM AND
IS SUPPORTING THE SLOW INTENSIFICATION OBSERVED IN THE PAST 12
HOURS. DRY AIR CONTINUES TO WRAP ALONG THE SOUTHERN PERIPHERY, BUT
IS SLOWLY WEAKENING AS OBSERVED IN ANIMATED WATER VAPOR IMAGERY AND
MSI. TS 11W IS CURRENTLY STEERING ALONG THE SOUTHERN PERIPHERY OF
THE SUBTROPICAL RIDGE (STR) TO THE NORTH.
3. FORECAST REASONING.
   A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM
THE PREVIOUS PROGNOSTIC REASONING.
   B. TS 11W IS FORECAST TO STAY ON A STEADY TRACK TOWARD MAINLAND
CHINA, TRACKING WESTWARD UNDER THE INFLUENCE OF THE STR TO THE
NORTH. A SLOW INTENSIFICATION OVER THE NEXT 24 HOURS WILL BRING THE
SYSTEM TO TYPHOON STRENGTH AS IT MOVES OVER VERY WARM SEA SURFACE
TEMPERATURES ASSOCIATED WITH THE KUROSHIO CURRENT AND AN IMPROVING
POLEWARD OUTFLOW CHANNEL. THIS INTENSIFICATION WILL BE SHORT-LIVED
AS THE SYSTEM IS EXPECTED TO MAKE LANDFALL SHORTLY BEFORE TAU 36.
THE UPPER LEVEL ENVIRONMENT REMAINS THE LIMITING FACTOR TO A GREATER
DEVELOPMENTAL POTENTIAL. ONE CONCERN IS THE IMPACT OUTFLOW FROM TY
10W IS PLAYING ON THE EQUATORWARD OUTFLOW OF TS 11W AND THE VERTICAL
WIND SHEAR. AS THE TWO SYSTEMS APPROACH ONE ANOTHER THE POSSIBILITY
EXISTS FOR THE POLEWARD OUTFLOW FROM TY 10W TO IMPACT THE WESTERN
HALF OF TS 11W, STIFLING OUTFLOW AND INCREASING VERTICAL WIND SHEAR.
MODEL GUIDANCE HAS STARTED TO TIGHTEN IN THE LATER TAUS, WITH JGSM
BEING THE NORTHERN OUTLIER, ALTHOUGH IT TOO HAS COME SOUTHWARD OVER
THE PAST SIX HOURS. THE OFFICIAL JTWC TRACK FORECAST IS BASED ON THE
MODEL CONSENSUS WITH HIGH CONFIDENCE.//
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