Tropical Storm KHANUN Advisory 14.10.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 24W (KHANUN)
WARNING NR 08//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 24W (KHANUN), LOCATED APPROXIMATELY 212 NM
WEST OF MANILA, PHILIPPINES, HAS TRACKED WEST-NORTHWESTWARD AT 04
KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY DEPICTS A STRUGGLING SYSTEM, WITH THE DEEP CONVECTION THAT
WAS PRESENT A FEW HOURS AGO RAPIDLY DISSIPATING. WARMER AND
SHALLOWER CONVECTION CONTINUES TO WRAP INTO A CLOUD-COVERED LOW
LEVEL CIRCULATION CENTER (LLCC) BUT MOST OF THE DEEPEST CONVECTIVE
ACTIVITY IS CONFINED FAR TO THE SOUTH OF THE LLCC. A 132251Z SSMIS
37GHZ MICROWAVE IMAGE SHOWS CONVECTIVE BANDING WRAPPING INTO A WELL
DEFINED BUT BROAD LLCC. THE INITIAL INTENSITY REMAINS STEADY AT 50
KNOTS BASED ON MULTI-AGENCY DVORAK ESTIMATES BETWEEN T3.0 AND T3.5
(45-55 KNOTS) FROM PGTW, RTJD AND KNES AND IS SLIGHTLY BELOW THE
AUTOMATED DVORAK AND SATELLITE CONSENSUS ESTIMATES. ENVIRONMENTAL
ANALYSIS INDICATES A MARGINAL ENVIRONMENT WITH MODERATE VERTICAL
WIND SHEAR (15 TO 20 KNOTS) AND A SINGLE, WEAK WESTWARD OUTFLOW
CHANNEL. SEA SURFACE TEMPERATURES REMAIN WARM IN THE AREA (29-30
CELSIUS). TS 24W IS UNDER THE STEERING INFLUENCE OF A THE DEEP-LAYER
SUBTROPICAL RIDGE (STR) CENTERED TO THE NORTHEAST.
3. FORECAST REASONING.
     A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
     B. TS 24W HAS TURNED TOWARDS THE WEST-NORTHWEST, BUT HAS SLOWED
SIGNIFICANTLY OVER THE PAST SIX HOURS AS IT BEGAN ITS TURN. HOWEVER,
THE SYSTEM WILL INCREASE IN FORWARD SPEED OVER THE NEXT FEW HOURS,
AS IT TRACKS ALONG THE SOUTHWESTERN BOUNDARY OF THE DEEP STR, AND
TOWARD A BROAD WEAKNESS IN THE RIDGE. AN EXTENSION OF THE STR WILL
RIDGE IN TO THE NORTH OF TS 24W, LEADING TO A WESTWARD TRACK AFTER
TAU 36 AND THROUGH LANDFALL ALONG THE NORTHEAST COAST OF HAINAN. AS
THE SYSTEM WEAKENS AFTER INTERACTION WITH HAINAN AND BECOMES
SHALLOW, THE REMNANTS WILL START TO TRACK SOUTHWESTWARDS THROUGH TAU
72. TS 24W WILL SLOWLY INTENSIFY AS IT CONTINUES TRACKING OVER THE
WARM WATERS OF THE SOUTH CHINA SEA, PEAKING AT 65 KNOTS AT TAU 36.
INTENSIFICATION WILL BE SOMEWHAT LIMITED AS UPPER LEVEL OUTFLOW IS
RESTRICTED TO A SINGLE WESTWARD OUTFLOW CHANNEL. BEYOND TAU 36, THE
SYSTEM WILL WEAKEN SLIGHTLY BEFORE MAKING LANDFALL AS UPPER-LEVEL
DIVERGENCE DECREASES AS A BAND OF STRONG 200 MB WINDS APPROACHES THE
SYSTEM FROM THE SOUTHEAST, FURTHER RESTRICTING UPPER-LEVEL EXHAUST.
NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT ON THE WEST-
NORTHWESTWARD TRACK THROUGH TAU 72 AND THE JTWC TRACK LIES JUST
SOUTH OF THE MULTI-MODEL CONSENSUS.
     C. IN THE EXTENDED PERIOD, TS 24W WILL REEMERGE IN THE GULF OF
TONKIN BY TAU 72 AS A WEAK TROPICAL STORM, AND TRACK SOUTHWESTWARD
UNDER THE INFLUENCE OF THE SYNOPTIC LOW-LEVEL FLOW, BEFORE MAKING A
SECOND LANDFALL ALONG THE CENTRAL VIETNAM COAST NEAR TAU 90. THE
SYSTEM WILL CONTINUE TO WEAKEN AS IT TRANSITS ACROSS THE GULF OF
TONKIN DUE TO STRONG VWS AND RESTRICTED OUTFLOW. AFTER MAKING
LANDFALL IN VIETNAM, THE SYSTEM WILL RAPIDLY DISSIPATE OVER HIGHER
TERRAIN. OVERALL, DYNAMIC MODEL GUIDANCE IS IN GOOD AGREEMENT
THROUGH THE EXTENDED PORTION OF THE FORECAST, WITH SOME INCREASED
SPREAD BEYOND TAU 96 AS THE SYSTEM WEAKENS AND THE MODELS LOSE THE
SIGNATURE. OVERALL THERE IS HIGH CONFIDENCE IN THE JTWC FORECAST
TRACK.//
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