簽到天數: 1715 天 [LV.Master]伴壇終老
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howard2639|2012-5-23 21:42
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1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM (TS) 03W (SANVU), LOCATED APPROXIMATELY 450 NM
SOUTH-SOUTHWEST OF IWO TO, JAPAN, HAS TRACKED NORTHWESTWARD AT 10
KNOTS OVER THE PAST SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY
SHOWS THE FEEDER BANDS, MOSTLY ALONG THE EASTERN SEMI-CIRCLE, HAVE
DEEPENED AND WRAPPED TIGHTER INTO THE LOW LEVEL CIRCULATION CENTER.
THE INITIAL POSITION WAS BASED ON THE ABOVE ANIMATION AND
EXTRAPOLATED FROM AN ARC FEATURE ON A 230752Z SSMIS MICROWAVE IMAGE.
THE INITIAL INTENSITY WAS BASED ON THE HIGH END OF DVORAK ESTIMATES
FROM PGTW, KNES, AND RJTD. UPPER LEVEL ANALYSIS INDICATES TS 03W IS
DIRECTLY UNDER A RIDGE AXIS IN AN AREA OF LIGHT (05-10 KNOT) VERTICAL
WIND SHEAR (VWS). THE FRONT SLOPE OF AN APPROACHING MID-LATITUDE
TROUGH TO THE NORTHWEST IS ENHANCING POLEWARD OUTFLOW. THIS IS
EVIDENT ON RECENT ANIMATED WATER VAPOR SATELLITE IMAGERY.
ADDITIONALLY, THE EQUATORWARD OUTFLOW HAS IMPROVED, ALTHOUGH NOT AS
ROBUST AS ON THE POLEWARD SIDE. THE CYCLONE IS TRACKING ALONG THE
SOUTHWEST PERIPHERY OF A SUBTROPICAL RIDGE (STR) EXTENSION TO THE
NORTHEAST. IN ADDITION TO THE LIGHT VWS AND GOOD OVERALL OUTFLOW, THE
ALONG-TRACK SEA SURFACE TEMPERATURE (SST) AT 29-30 DEGREES CELSIUS,
IS ALSO FAVORABLE FOR CONTINUED DEVELOPMENT.
3. FORECAST REASONING.
A. THE FORECAST PHILOSOPHY HAS NOT CHANGED SINCE THE PREVIOUS
PROGNOSTIC REASONING BULLETIN.
B. IN VIEW OF THE FAVORABLE CONDITIONS MENTIONED ABOVE, TS 03W IS
EXPECTED TO CONTINUE INTENSIFYING AS IT ROUNDS THE WESTERN EDGE OF
THE STEERING STR OVER THE NEXT 36-48 HOURS EVEN SHORTLY AFTER
RECURVING TO THE NORTHEAST. THE STRONG WESTERLIES ASSOCIATED WITH
THE SUBTROPICAL JET STREAM WILL PROVIDE EXCELLENT OUTFLOW PRIOR TO
AND RIGHT AFTER RECURVATURE. THIS, IN ADDITION TO THE LIGHT VWS AND
WARM SST, WILL FUEL THE INTENSIFICATION. AFTER TAU 48, INCREASING VWS
AND COOLING SST'S WILL CAUSE THE RAPID DECAY OF TS 03W. THIS WILL
COINCIDE WITH THE SYSTEM'S EXTRA-TROPICAL TRANSITION (ETT) AND
ABSORPTION INTO THE BAROCLINIC ZONE.
C. BY TAU 72, TS SANVU WILL ACCELERATE NORTHEASTWARD AND
COMPLETE ETT BY TAU 96. THE AVAILABLE NUMERICAL GUIDANCE REMAINS
TIGHTLY PACKED WITH THE EXCEPTION OF EGRR'S LEFTWARD DEFLECTION
AFTER TAU 48. THIS TRACK FORECAST IS VERY CLOSE TO MODEL CONSENSUS
(CONW) BUT SLIGHTLY TO THE RIGHT OF AND FASTER THAN CONW AFTER TAU 48
TO ACCOUNT FOR EGRR'S UNLIKELY LEFTWARD MOTION AND FOR KNOWN MODELS'
TENDENCY TO SLOW DOWN DURING RECURVATURE. |
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