Tropical Storm MEKKHALA Advisory 8月11日

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 07W (MEKKHALA)
WARNING NR 006//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM 07W (MEKKHALA), LOCATED APPROXIMATELY 224 NM
EAST OF HONG KONG, HAS TRACKED NORTHWARD AT 13 KNOTS OVER THE PAST
SIX HOURS. ANIMATED ENHANCED INFRARED (EIR) SATELLITE DEPICTS A
RAGGED AND SOMEWHAT DISORGANIZED STRUCTURE WITH FLARING CONVECTION
CONFINED MOSTLY TO THE SOUTHERN SIDE OF THE SYSTEM BUT WITH SOME
DEVELOPING CONVECTIVE ACTIVITY BEGINNING TO WRAP ON THE EASTERN
AND NORTHERN SIDES OF THE ASSESSED CENTER IN SUBSEQUENT IMAGERY.
WHILE THE INFRARED DEPICTION IS RAGGED AND DISORGANIZED, THE
MICROWAVE AND RADAR DEPICTIONS ARE SURPRISINGLY CLEAR, WITH A
DISTINCT MICROWAVE EYE EVIDENT IN THE 101731Z GPM 37 GHZ IMAGERY
AND A CLEAR CUT CENTER OF CIRCULATION IN THE RADAR COMPOSITE. THE
CURRENT POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE
AFOREMENTIONED MICROWAVE DATA AND RADAR FIX FROM 101800Z. THE
CURRENT INTENSITY OF 55 KNOTS IS SET WITH MODERATE CONFIDENCE
BASED ON AN ASSESSMENT OF MULTIAGENCY DVORAK CURRENT INTENSITY
ESTIMATES OF T3.0 (45 KNOTS) FROM PGTW AND RCTP AND T2.5 (35
KNOTS) FROM RJTD, AN ADT OF 3.2 (49 KNOTS) AND A SATELLITE
CONSENSUS ESTIMATE OF 47 KNOTS. DVORAK ESTIMATES ARE LIKELY TOO
LOW DUE TO THE SMALL NATURE OF THE SYSTEM, HENCE THE CURRENT
INTENSITY IS NUDGED HIGHER DUE TO THE OVERALL STRUCTURE OF THE
SYSTEM IN THE MICROWAVE AND RADAR DATA. THE SYSTEM IS SITUATED IN
A SHORT-TERM FAVORABLE ENVIRONMENT FOR DEVELOPMENT WITH MODERATE
(15-20 KTS) VERTICAL WIND SHEAR AND WARM (28-29 DEG C) SEA SURFACE
TEMPERATURES. THE SYSTEM IS TRANSITING THROUGH A COMPLEX UPPER
LEVEL OUTFLOW ENVIRONMENT WITH THE SOUTHERN EDGE OF A MID-LATITUDE
TROUGH TO THE NORTH PROVIDING SOME WEAK POLEWARD OUTFLOW WHILE
SUB-TROPICAL RIDGES LOCATED OVER WESTERN CHINA AND OVER THE
PHILIPPINE SEA ARE PROVIDING THE EQUATORWARD OUTFLOW. THE SYSTEM
IS TRACKING NORTHWARD ALONG THE WESTERN PERIPHERY OF A DEEP-LAYER
STR LOCATED TO THE EAST.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
   B. TS 07W WILL CONTINUE TO TRACK POLEWARD ALONG THE WESTERN
PERIPHERY OF THE STR THROUGH THE ENTIRE FORECAST PERIOD AND IS
EXPECTED TO MAKE LANDFALL IN SOUTHEASTERN CHINA NEAR THE 102100Z
HOUR. RADAR IMAGERY SINCE 1800Z SHOWS THE SYSTEM IS CONTINUING TO
INTENSIFY WITH AN EYEWALL NOW NEARLY SURROUNDING THE CENTER. WHILE
THE 12 HOUR FORECAST POSITION MAINTAINS THE INITIAL INTENSITY OF
55 KNOTS, THE SYSTEM IS EXPECTED TO INTENSIFY PRIOR TO LANDFALL,
BETWEEN THE FORECAST TAUS. TAKING ADVANTAGE OF THE SHORT-TERM
FAVORABLE CONDITIONS OF DUAL-CHANNEL OUTFLOW AND HIGH SSTS, THE
SYSTEM IS FORECAST TO REACH A PEAK INTENSITY OF 65 KNOTS BEFORE
LANDFALL. AFTER THE SYSTEM MAKES LANDFALL IT WILL RAPIDLY WEAKEN
DUE TO THE FRICTIONAL EFFECTS OF LAND AND FULLY DISSIPATE OVER
LAND NORTHWEST OF SHANGHAI BY TAU 36. NUMERICAL MODEL SOLUTIONS
ARE IN GOOD AGREEMENT THROUGH THE FORECAST PERIOD, LENDING OVERALL
HIGH CONFIDENCE IN JTWC TRACK FORECAST.//
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