Tropical Storm KHANUN Advisory сб, 14.10.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 24W (KHANUN)
WARNING NR 07//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 24W (KHANUN), LOCATED APPROXIMATELY 200 NM
WEST OF MANILA, PHILIPPINES, HAS TRACKED WESTWARD AT 06 KNOTS OVER
THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY
INDICATES DEEP CONVECTIVE BANDING ALONG THE SOUTHERN PERIPHERY OF
THE CLOUD COVERED LOW LEVEL CIRCULATION CENTER (LLCC). A 131346Z
AMSU-B 89GHZ MICROWAVE IMAGE SHOWED A BROAD AND WEAK LLCC, WITH
DEEP CONVECTION WRAPPING AROUND THE WEST TO SOUTHWEST QUADRANTS OF
THE SYSTEM. COINCIDENT SCATTEROMETER DATA DEPICTED THE LLCC QUITE
CLEARLY, WITH HIGHER WINDS ALONG THE SOUTHWEST AND NORTHWEST
QUADRANTS, PART OF AN ASYMMETRIC WIND FIELD. THE INITIAL INTENSITY
HAS BEEN LOWERED TO 50 KNOTS BASED ON A DVORAK ESTIMATE OF T3.0 (45
KNOTS) FROM PGTW, RTJD AND KNES, THE SCATTEROMETER DATA, AN
AUTOMATED DVORAK TECHNIQUE (ADT) ESTIMATE OF T3.3 (52 KNOTS) AND A
SATELLITE CONSENSUS OF 49 KNOTS. UPPER-LEVEL ANALYSIS DEPICTS A
MARGINALLY FAVORABLE ENVIRONMENT WITH MODERATE VERTICAL WIND SHEAR
(15 TO 20 KNOTS) AND WEAK WESTWARD AND EQUATORWARD OUTFLOW. SEA
SURFACE TEMPERATURES REMAIN WARM (29-30 CELSIUS). TS 24W IS UNDER
THE STEERING INFLUENCE OF A THE DEEP-LAYER SUBTROPICAL RIDGE (STR)
ENTRENCHED TO THE NORTHEAST.
3. FORECAST REASONING.
     A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
     B. TS 24W WILL BEGIN TO TRACK MORE WEST-NORTHWESTWARD OVER THE
NEXT 12 HOURS, ALONG THE SOUTHWESTERN BOUNDARY OF THE DEEP STR, AND
TOWARD A BROAD WEAKNESS IN THE RIDGE. AFTER TAU 48, AN EXTENSION OF
THE STR WILL BEGIN TO NOSE IN TO THE NORTH OF TS 24W, DRIVING THE
SYSTEM ON TO A MORE WESTWARD TRACK TOWARDS HAINAN ISLAND. 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, FAIRLY WEAK, WESTWARD CHANNEL. BEYOND TAU
36, THE SYSTEM WILL WEAKEN SLIGHTLY BEFORE MAKING LANDFALL AS VWS
INCREASES AND UPPER-LEVEL DIVERGENCE DECREASES AS A BAND OF STRONG
200 MB WINDS APPROACHES THE SYSTEM FROM THE SOUTHEAST, CONSTRICTING
OUTFLOW. NUMERICAL MODEL GUIDANCE IS IN GENERALLY GOOD AGREEMENT
WITH A WEST-NORTHWESTWARD TRACK THROUGH TAU 48 AND THE JTWC TRACK
LIES TO THE SOUTH OF THE MULTI-MODEL CONSENSUS.
     C. IN THE EXTENDED PERIOD, TS 24W WILL TRACK WESTWARD ACROSS
HAINAN AND MAKE A SECOND LANDFALL IN NORTHERN VIETNAM NEAR TAU 100.
THE SYSTEM WILL WEAKEN SIGNIFICANTLY AS IT CROSSES THE MOUNTAINOUS
TERRAIN OF HAINAN, AND REEMERGE AS A TROPICAL DEPRESSION. AFTER
MAKING LANDFALL IN VIETNAM, THE SYSTEM WILL RAPIDLY DISSIPATE OVER
HIGHER TERRAIN. OVERALL, DYNAMIC MODEL GUIDANCE IS IN GOOD
AGREEMENT. PREVIOUS MODEL RUNS DEPICTING A TURN TO THE SOUTH AFTER
TAU 72 WERE CONSIDERED AS ERRONEOUS. NEARLY ALL MODELS HOWEVER ARE
NOW DEPICTING THIS SOUTHERN TURN ONCE THE SYSTEM REEMERGES INTO THE
GULF OF TONKIN. THE OFFICIAL FORECAST TRACK TAKES THIS INTO ACCOUNT
AND SHOWS THIS TURN SOUTHWESTWARDS TOWARDS THE COAST OF VIETNAM.
OVERALL THERE IS HIGH CONFIDENCE IN THE JTWC FORECAST TRACK.//
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