Tropical Storm KALMAEGI Advisory Sun Sep 14

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 15W (KALMAEGI) WARNING
NR 11//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 15W (KALMAEGI), LOCATED APPROXIMATELY 377 NM
EAST OF MANILA, PHILIPPINES, HAS TRACKED WEST-NORTHWESTWARD AT 14
KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY INDICATES A CONSOLIDATING LOW-LEVEL CIRCULATION CENTER
(LLCC) WITH A PERSISTENT CENTRAL DENSE OVERCAST FEATURE (CDO) WHILE
CONVECTIVE BANDING HAS CONTINUED TO IMPROVE ACROSS THE WESTERN SEMI-
CIRCLE OF THE SYSTEM. A 130521Z AMSU-B MICROWAVE IMAGE DEPICTS
STRONG CONVECTIVE BANDING WRAPPING TIGHTLY INTO A WELL-DEFINED LLCC
THAT IS BEING OBSCURED BY THE CDO FEATURE. THERE IS GOOD CONFIDENCE
IN THE INITIAL POSITION BASED UPON THE AFOREMENTIONED SATELLITE
IMAGERY. THE INITIAL INTENSITY HAS BEEN INCREASED TO 60 KNOTS BASED
ON THE IMPROVED BANDING WHILE DVORAK INTENSITY ESTIMATES FROM ALL
REPORTING AGENCIES REMAIN AT 55 KNOTS. UPPER LEVEL ANALYSIS REVEALS
MODERATE NORTHEASTERLY VERTICAL WIND SHEAR (VWS) ACROSS THE NORTHERN
PORTION OF THE SYSTEM, WHICH IS HINDERING THE CONVECTION ACROSS THE
NORTHERN SEMI-CIRCLE; HOWEVER, THE SOUTHERN SEMI-CIRCLE OF THE
SYSTEM IS EXPERIENCING LOW VWS AND GOOD EQUATORWARD OUTFLOW WHICH IS
ADDITIONALLY BEING ENHANCED BY A TUTT CELL LOCATED NEAR GUAM. TS 15W
IS CURRENTLY TRACKING WEST-NORTHWESTWARD BY A BUILDING, EAST-WEST
ORIENTED SUBTROPICAL RIDGE (STR) ENTRENCHED TO NORTH OF THE SYSTEM.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
   B. TS 15W IS FORECAST TO TRACK WEST-NORTHWESTWARD UNDER THE
STEERING INFLUENCE OF THE DOMINANT STR THROUGH THE REMAINDER OF THE
FORECAST. TS 15W WILL CONTINUALLY INTENSIFY THROUGH TAU 24
UNDER FAVORABLE ENVIRONMENTAL CONDITIONS TO INCLUDE WARM SEA SURFACE
TEMPERATURES, HIGH OCEAN HEAT CONTENT AND GOOD OUTFLOW. TS KALMAEGI
IS FORECAST TO MAKE LANDFALL OVER EASTERN LUZON AFTER TAU 24,
LEADING TO A TEMPORARY WEAKENING AS IT CROSSES THE ROUGH TERRAIN OF
LUZON.
   C. IN THE EXTENDED TAUS, TS 15W IS EXPECTED TO CONTINUE ON A WEST-
NORTHWESTWARD TRACK ACROSS THE SOUTH CHINA SEA AND ACROSS THE
LUICHOW PENINSULA. FAVORABLE ENVIRONMENTAL CONDITIONS IN THE SOUTH
CHINA SEA (SCS) WILL FURTHER ALLOW TS 15W TO RE-INTENSIFY AS IT
TRACKS ACROSS THE NORTHERN SCS. AFTER TAU 72, TS 15W IS FORECAST TO
WEAKEN AS IT APPROACHES THE SOUTHERN COAST OF CHINA BEFORE IT
EVENTUALLY DISSIPATES BY TAU 120 OVERLAND. DYNAMIC MODEL GUIDANCE
(INCLUDING THE MODEL ENSEMBLES) IS IN TIGHT AGREEMENT, THEREFORE,
THERE IS HIGH CONFIDENCE IN THE JTWC FORECAST TRACK, WHICH IS
POSITIONED CLOSE TO THE MULTI-MODEL CONSENSUS.//
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