Tropical Storm MEKKHALA Advisory 8月10日

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 07W (SEVEN) WARNING
NR 002//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION 07W (SEVEN), LOCATED APPROXIMATELY 265 NM NORTH-
NORTHWEST OF MANILA, PHILIPPINES, HAS TRACKED NORTHWARD AT 13 KNOTS
OVER THE PAST SIX HOURS. THE CURRENT POSITION IS BASED ON A 091751Z
ATMS IMAGE AND SATELLITE FIXES FROM PGTW AND RJTD. THE INTENSITY OF 30
KNOTS IS CONSISTENT WITH A CONSENSUS OF SUBJECTIVE DVORAK AND AUTOMATED
INTENSITY ESTIMATES AND METOP-A ASCAT DATA FROM 091202Z INDICATING AN
EXTENSIVE AREA OF 30 KNOT WINDS SITUATED TO THE EAST AND SOUTH OF THE
LOW-LEVEL CIRCULATION CENTER. THE LOW-LEVEL CIRCULATION IS PARTIALLY
EXPOSED, WITH PATCHY DEEP CONVECTION DEVELOPING AND ROTATING AROUND THE
PERIPHERY. TD 07W IS TRACKING POLEWARD ALONG THE WESTERN PERIPHERY OF A
SUBTROPICAL STEERING RIDGE (STR) EXTENSION. THE SYSTEM IS SITUATED IN
AN AREA OF LIGHT TO MODERATE (10-15 KTS) VERTICAL WIND SHEAR AND VERY
WARM (30-31C) SEA SURFACE TEMPERATURES. UPPER-LEVEL DIFFLUENCE IS
LIMITED.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
   B. TD 07W WILL CONTINUE TO TRACK POLEWARD ALONG THE STR THROUGH THE
FORECAST PERIOD, MAKING LANDFALL IN SOUTHEASTERN CHINA AROUND TAU 30.
STEADY INTENSIFICATION IS ANTICIPATED PRIOR TO LANDFALL, DESPITE
PERSISTENT VERTICAL WIND SHEAR, DUE TO CONTINUED PASSAGE OVER VERY WARM
WATER AND INCREASING POLEWARD OUTFLOW AIDED BY AN UPPER-LEVEL TROUGH TO
THE NORTHEAST. AFTER THE SYSTEM MAKES LANDFALL, IT WILL WEAKEN DUE TO
THE FRICTIONAL EFFECTS OF LAND AND DISSIPATE BY TAU 48. NUMERICAL MODEL
FORECASTS ARE IN GOOD AGREEMENT REGARDING THE OVERALL FORECAST
SCENARIO, BUT THERE IS SOME SPREAD IN THE EXACT DIRECTION AND SPEED OF
MOVEMENT. OVERALL, THERE IS FAIR CONFIDENCE IN JTWC FORECAST TRACK.//
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