Tropical Storm MELOR Advisory Sáb, 12-12

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 28W (MELOR) WARNING NR
04//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 28W (MELOR), LOCATED APPROXIMATELY 759 NM
EAST-SOUTHEAST OF MANILA, PHILIPPINES, HAS TRACKED WEST-NORTHWESTWARD
AT 12 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY (MSI) SHOWS A CONSOLIDATING LOW LEVEL CIRCULATION CENTER
(LLCC) WITH SPIRAL BANDING WRAPPING TIGHTER INTO THE LLCC. THE
INITIAL POSITION IS BASED ON THE MSI LOOP AND AN LLCC FEATURE IN THE
120521Z SSMI MICROWAVE PASS WITH GOOD CONFIDENCE. THE INITIAL
INTENSITY OF 50 KNOTS IS HELD SLIGHTLY HIGHER THAN AGENCY DVORAK
ESTIMATES TO REFLECT THE IMPROVED BANDING. ENVIRONMENTAL CONDITIONS
REMAIN FAVORABLE WITH LOW (05-10 KNOT) VERTICAL WIND SHEAR (VWS),
EXCELLENT POLEWARD OUTFLOW, AND WARM SEA SURFACE TEMPERATURES (ABOVE
28 CELSIUS). THE CYCLONE IS TRACKING ALONG THE SOUTHERN PERIPHERY OF
A DEEP-LAYERED SUB-TROPICAL RIDGE (STR) TO THE NORTH.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
   B. TS MELOR WILL CONTINUE TO TRACK WEST-NORTHWESTWARD UNDER THE
STEERING INFLUENCE OF THE STR. FAVORABLE ENVIRONMENTAL CONDITIONS
WILL PERSIST AND SUPPORT STEADY INTENSIFICATION, PEAKING AT 85 KNOTS
BY TAU 48 BEFORE MAKING LANDFALL IN SOUTHERN LUZON NEAR SORSOGON.
   C. BEYOND TAU 72, VWS WILL INCREASE AS A STRONG NORTHERLY COLD
SURGE FROM CHINA CROSSES THE STORM TRACK AND FLOWS IN CONTRAST WITH
THE UPPER LEVEL WINDS. IN ADDITION, TS 28W WILL ENCOUNTER THE RUGGED
TERRAIN OF THE PHILIPPINE ISLANDS. THE COMBINATION OF THESE TWO
NEGATIVE ENVIRONMENTAL EFFECTS WILL RAPIDLY ERODE THE CYCLONE,
REDUCING IT TO A 35-KNOT SYSTEM BY TAU 120. DYNAMIC MODEL GUIDANCE IS
IN GOOD AGREEMENT THROUGH TAU 72 WITH SIGNIFICANT SPREADING
AFTERWARDS. IN VIEW OF THIS, THERE IS HIGH CONFIDENCE IN THE JTWC
FORECAST ONLY UP TO TAU 72.//
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