Tropical Storm MERBOK Advisory Mon Jun 12

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 04W (MERBOK)
WARNING NR 02//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION 04W (MERBOK), LOCATED APPROXIMATELY 298 NM
WEST-NORTHWEST OF MANILA, PHILIPPINES, HAS TRACKED NORTH-
NORTHWESTWARD AT 11 KNOTS OVER THE PAST SIX HOURS. ANIMATED
MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS THE SYSTEM CONTINUING TO
CONSOLIDATE WITH CONVECTIVE BANDING WRAPPING INTO PERSISTENT
CONVECTION LOCATED TO THE SOUTHEAST OF THE LOW LEVEL CIRCULATION
CENTER (LLCC). THE INITIAL POSITION IS BASED ON THE MSI AND
EXTRAPOLATION FROM AN 110204Z METOP-B AMSU 89GHZ MICROWAVE IMAGE.
THE INITIAL INTENSITY OF 30 KNOTS IS BASED ON MULTI AGENCY DVORAK
ESTIMATES OF T2.0 AND AN 110205Z METOP-B ASCAT PASS SHOWING 30 KNOT
WIND BARBS IN THE EASTERN SEMI-CIRCLE. ENVIRONMENTAL ANALYSIS
INDICATES FAVORABLE CONDITIONS FOR FURTHER DEVELOPMENT WITH LOW
VERTICAL WIND SHEAR VALUES (10-15 KNOTS), STRONG EQUATORWARD
OUTFLOW, AND WARM SEA SURFACE TEMPERATURES (30-31 C). TROPICAL
DEPRESSION (TD) 04W IS CURRENTLY TRACKING TO THE NORTHWEST ALONG THE
WESTERN PERIPHERY OF A SUBTROPICAL RIDGE.
3. FORECAST REASONING.
   A. NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TD 04W IS EXPECTED TO CONTINUE TO TRACK TO THE NORTHWEST ALONG
THE WESTERN PERIPHERY OF A SUBTROPICAL RIDGE (STR). THE SYSTEM IS
FORECAST TO MAKE LANDFALL TO THE EAST OF HONG KONG JUST BEFORE TAU
36. ONCE 04W MAKES LANDFALL IT WILL ROUND THE NORTHWESTERN EDGE OF
THE STR, EXIT INTO THE EAST CHINA AND ACCELERATE NORTHEASTWARD. THE
CURRENT FAVORABLE ENVIRONMENT WILL CAUSE THE SYSTEM TO GRADUALLY
INTENSIFY, PEAKING AT 40 KNOTS JUST PRIOR TO LANDFALL. POST
LANDFALL, LAND INTERACTION WILL CAUSE TD 04W TO RAPIDLY
DISSIPATE.
   C. AFTER TAU 72, TD 04W WILL CONTINUE TO DETERIORATE AS IT TRACKS
TO NORTHEAST. DYNAMIC MODEL GUIDANCE IS IN STRONG AGREEMENT THAT THE
SYSTEM WILL TURN TO THE EAST, WITH VARIATION IN HOW RAPIDLY THE TURN
OCCURS. THE CONSENSUS HAS THE SYSTEM TRACKING NORTH OF OKINAWA WHICH
IS WHERE THE JTWC OFFICIAL FORECAST TRACK IS LOCATED. JTWC HAS HIGH
CONFIDENCE IN ITS FORECAST TRACK UNTIL TAU 72 WHEN THE VARIATIONS IN
TRACK LOCATION BY THE DYNAMIC MODEL GUIDANCE LENDS LOW CONFIDENCE IN
THE JTWC TRACK FORECAST.//
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