Tropical Storm TWENTYNINE Advisory mar, 07-11

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 29W (TWENTYNINE)
WARNING NR 01//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION (TD) 29W (TWENTYNINE), LOCATED APPROXIMATELY
290NM WEST-SOUTHWEST OF HO CHI MINH CITY, VIETNAM, HAS TRACKED
NORTHWARD AT 09 KNOTS OVER THE PAST SIX HOURS. ANIMATED
MULTISPECTRAL SATELLITE IMAGERY DEPICTS A CONSOLIDATING, PARTIALLY-
EXPOSED LOW-LEVEL CIRCULATION CENTER (LLCC) WITH FRAGMENTED DEEP
CONVECTIVE BANDING WRAPPING INTO AN ELONGATED CENTER. A 060244Z
METOP-B 89GHZ COMPOSITE IMAGE ALSO SHOWS FRAGMENTED DEEP CONVECTIVE
BANDING BUT DEPICTS SHALLOW BANDING WRAPPING TIGHTLY INTO A DEFINED
CENTER, WHICH SUPPORTS THE INITIAL POSITION WITH FAIR CONFIDENCE. A
060232Z OSCAT IMAGE SHOWS A DEFINED CIRCULATION WITH 20 TO 30 KNOT
WINDS OVER THE NORTHERN SEMI-CIRCLE AND 15 KNOT WINDS OVER THE
SOUTHERN SEMI-CIRCLE. THE INITIAL INTENSITY IS ASSESSED AT 25 KNOTS
BASED ON THE ASCAT DATA AND DVORAK INTENSITY ESTIMATES OF 25 KNOTS.
UPPER-LEVEL CONDITIONS ARE FAVORABLE WITH LOW VERTICAL WIND SHEAR (5-
10 KNOTS) AND GOOD POLEWARD OUTFLOW. TD 29W IS TRACKING POLEWARD
ALONG THE SOUTHWEST PERIPHERY OF A LOW- TO MID-LEVEL SUBTROPICAL
RIDGE (STR) POSITIONED TO THE EAST AND NORTHEAST.
3. FORECAST REASONING.
   A. THIS IS THE FIRST PROGNOSTIC REASONING MESSAGE AND SETS THE
FORECAST PHILOSOPHY.
   B. TD 29W IS FORECAST TO TURN NORTHWESTWARD TO WEST-NORTHWESTWARD
AS IT STRENGTHENS AND STEERS UNDER AN EAST-WEST ORIENTED MID-LEVEL
STR POSITIONED TO THE NORTH, ALONG 18-20N LATITUDE. THE SYSTEM IS
EXPECTED TO INTENSIFY TO 40 KNOTS UNDER FAVORABLE CONDITIONS UNTIL
IT MAKES LANDFALL OVER THE MALAY PENINSULA NEAR TAU 24. TD 29W WILL
WEAKEN AS IT CROSSES THE MALAY PENINSULA BUT IS EXPECTED TO RE-
INTENSIFY AS IT TRANSITS THE ANDAMAN SEA.
   C. AFTER TAU 72, TD 29W WILL SLOW AS IT APPROACHES A BROAD BREAK
IN THE STR ASSOCIATED WITH A SHORTWAVE TROUGH DIGGING OVER
BANGLADESH. AS A RESULT OF THE WEAKENING STEERING INFLUENCE, THERE
IS INCREASING UNCERTAINTY IN THE FORECAST TRACK WITH A LARGE SPREAD
IN THE DYNAMIC MODEL SOLUTIONS. TD 29W IS FORECAST TO SIGNIFICANTLY
INTENSIFY TO A PEAK INTENSITY OF 70 KNOTS BY TAU 120 AS IT DEVELOPS
A ROBUST POLEWARD OUTFLOW CHANNEL. OVERALL, THERE IS LOW CONFIDENCE
IN THE JTWC FORECAST TRACK.//
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