TROPICAL CYCLONE CHABA; TC RICHARD; TCFA 91S

TROPICAL CYCLONE CHABA


WDPN32 PGTW 260300
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 16W WARNING NR 19//
RMKS/
1. FOR METEOROLOGISTS.
2. 12 HOUR SUMMARY AND ANALYSIS.
   A. TYPHOON 16W (CHABA), LOCATED APPROXIMATELY 430 NM SOUTH-
SOUTHEAST OF KADENA AIR BASE, JAPAN, HAS TRACKED NORTH-NORTHWESTWARD 
AT 5 KNOTS DURING THE PAST SIX HOURS. ANIMATED MULTI-SPECTRAL 
SATELLITE IMAGERY SHOWS CONVECTION INTENSIFYING AND CONSOLIDATING 
OVER THE LOW LEVEL CIRCULATION CENTER (LLCC). MARKEDLY IMPROVED 
POLEWARD OUTFLOW DURING THE PAST SIX HOURS IS RESPONSIBLE FOR MUCH 
OF THE INTENSIFICATION. A 252132Z 37GHZ MICROWAVE PASS SHOWS A 
DEVELOPING MICROWAVE EYE AND INCREASINGLY WELL ORGANIZED CONVECTIVE 
BANDING. INFRARED ANIMATION SHOWS A SHARP INCREASE IN COLD TOPS OVER 
THE LLCC DURING THE PAST SIX HOURS. THE INTENSITY ESTIMATE IS BASED 
ON A COMBINATION OF DVORAK ESTIMATES OF 65 KNOTS FROM PGTW AND 77 
KNOTS FROM RJTD. IN ADDITION TO THE IMPROVING POLEWARD OUTFLOW, WELL 
DEVELOPED EQUATORWARD OUTFLOW PERSISTS. 
3. FORECAST REASONING.
   A. THERE IS NO SIGNIFICANT CHANGE TO THE TRACK FORECAST
PHILOSOPHY. TRACK SPEEDS AFTER TAU 72 HAVE BEEN INCREASED.
   B. TYPHOON CHABA IS EXPECTED TO CONTINUE A STEADY POLEWARD TRACK 
AROUND THE PERIPHERY OF THE SUBTROPICAL RIDGE THROUGH TAU 48.
THE STORM WILL SUSTAIN INTENSIFICATION AS A MID-LATITUDE TROUGH 
CURRENTLY MOVING OVER THE SEA OF JAPAN PROVIDES FURTHER ENHANCEMENT 
TO THE POLEWARD OUTFLOW CHANNEL. A MID-LATITUDE SHORT WAVE TROUGH 
CURRENTLY OVER THE SEA OF JAPAN WILL ACT TO SUSTAIN A VIGOROUS 
POLEWARD OUTFLOW CHANNEL UNTIL IT PASSES EAST OF THE STORM. THIS 
WILL INDUCE STEADY INTENSIFICATION AS TY 16W ROUNDS THE WESTERN EDGE 
OF THE SUBTROPICAL RIDGE.  GFDN, FORMERLY AN OUTLIER TO THE EXTREME 
WEST, HAS NOW JOINED THE PACK AND IS TRACKING THE SYSTEM TO THE WEST
OF OKINAWA.
   C. A RECENT COLD SURGE OVER WESTPAC HAS BROUGHT CONTINENTAL POLAR 
AIR DEEP INTO THE THEATER, THEREFORE EXTRATROPICAL TRANSISTION WILL 
BEGIN BEFORE THE STORM REACHES 30N. TYPHOON CHABA IS EXPECTED TO 
RECURVE AND TRACK ALONG THE EAST COAST OF HONSHU AFTER TAU 72 WHILE 
UNDERGOING A RAPID EXTRA-TROPICAL TRANSITION. THE RECURVATURE WILL 
NOT BE A DRAMATIC TURN AND ACCELERATION DUE TO A ZONAL ORIENTATION 
OF THE POLAR FRONT JET DURING THAT PERIOD. THE ZONAL JET, HOWEVER, 
WILL PRODUCE TREMENDOUS VERTICAL WINDSHEAR BETWEEN 30 AND 35 NORTH 
LATITUDE. THEREFORE TYPHOON CHABA IS EXPECTED TO UNDERGO RAPID 
DE-INTENSIFICATION DURING ITS PERIOD OF EXTRATROPICAL TRANSITION. 
DURING THE SAME PERIOD,THE STORM WILL BE RIDING OVER A REGION OF 
RAPIDLY DECREASING OCEAN HEAT CONTENT. NUMERICAL MODELS ARE COMING 
INTO BETTER AGREEMENT WITH THIS SCENARIO. NOGAPS AND EGRR BOTH STEER 
THE STORM OVER SHIKOKU AND INTO THE SEA OF JAPAN, PUNCHING IT 
THROUGH A 100 KNOT POLAR FRONT JET AND OVER THE JAPANESE ALPS. THIS 
SOLUTION IS INCOHERENT AND IS DISREGARDED. BECAUSE THE CONSENSUS 
INCLUDES BOTH NOGAPS AND EGRR, THE FORECAST IS TO THE 
RIGHT AND FASTER THAN CONSENSUS, WHICH IS SLIGHTLY SLIGHTLY SLOWER 
BUT VERY CLOSE TO ECMWF. ECMWF HAS SHOWN THE BEST HANDLING OF THE 
SYSTEM'S TRACK THUS FAR.//
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TROPICAL CYCLONE 91S


WTXS21 PGTW 252300
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/TROPICAL CYCLONE FORMATION ALERT//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
A 180 NM RADIUS OF 9.6S 86.3E WITHIN THE NEXT 12 TO 24 HOURS.
AVAILABLE DATA DOES NOT JUSTIFY ISSUANCE OF NUMBERED TROPICAL
CYCLONE WARNINGS AT THIS TIME. WINDS IN THE AREA ARE ESTIMATED TO
BE 25 TO 30 KNOTS. METSAT IMAGERY AT 252251Z INDICATES THAT A
CIRCULATION CENTER IS LOCATED NEAR 9.6S 86.4E. THE SYSTEM IS
MOVING SOUTH-SOUTHEASTWARD AT 03 KNOTS.
2. REMARKS: THE AREA OF CONVECTION PREVIOUSLY LOCATED NEAR 10.0S 
86.1E IS NOW LOCATED NEAR 9.6S 86.4E, APPROXIMATELY 835 NM EAST OF 
DIEGO GARCIA. ANIMATED INFRARED SATELLITE IMAGERY INDICATES THAT 
VERTICAL WIND SHEAR (VWS) OVER THE LOW LEVEL CIRCULATION CENTER 
(LLCC) IS EASING AND CONVECTION IS CONSOLIDATING. A 251943Z AMSR-E 
36GHZ IMAGE DEPICTS CONVECTIVE BANDING ORGANIZING AND EMCOMPASSING 
ALL BUT THE EASTERN PORTION OF THE LLCC. THE LLCC IS LOCATED UNDER 
DIFFLUENT EASTERLY FLOW NORTH OF THE SUBTROPICAL RIDGE AXIS. VWS IS 
EXPECTED TO DECREASE OVER THE SHORT TERM AS THE LLCC DRIFTS 
SOUTHWARD. MODEL GUIDANCE INDICATES THE SYSTEM WILL BE DRIVEN 
WESTWARD BY A BUILDING LOW-LEVEL STEERING RIDGE AFTER TAU 24. A 
251523Z ASCAT IMAGE SHOWED NUMEROUS 30 KNOT WIND VECTORS NEAR THE 
CENTER. SURFACE WINDS ARE ESTIMATED AT 25 TO 30 KNOTS. MINIMUM SEA 
LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1000 MB. THE POTENTIAL FOR 
THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 
HOURS IS GOOD.
3. THIS ALERT WILL BE REISSUED, UPGRADED TO WARNING OR CANCELLED BY 
262300Z.
//
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TROPICAL CYCLONE RICHARD


260300Z POSITION NEAR 18.4N 91.6W OR APPROX 17NM SE OF 
CIUDAD DEL CARMEN, MEXICO. 12FT SEAS: NONE.
NEXT WARNINGS AT 260901Z, 261501Z, 262101Z AND 270301Z.//
BT
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