Tropical Storm FUNG-WONG Advisory vie, 19-09

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 16W (FUNG-WONG) WARNING
NR 07//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 16W (FUNG-WONG), LOCATED APPROXIMATELY 222 NM
NORTH-NORTHEAST OF MANILA, PHILIPPINES, HAS TRACKED NORTHWESTWARD AT
17 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR)
AND MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICT DEEP CONVECTIVE
BANDING ACROSS THE SOUTHWESTERN SEMI-CIRCLE OF A LOW LEVEL
CIRCULATION CENTER (LLCC) THAT HAS BECOME PARTIALLY OBSCURED BY
DEVELOPING CONVECTION OVER THE LAST 6 HOURS. A 182318z SSMIS
MICROWAVE IMAGE SHOWS DEEP CONVECTION ALONG THE SOUTHERN PERIPHERY
AND FORMATIVE CONVECTIVE BANDING NORTH OF THE SYSTEM. THE CURRENT
POSITION IS BASED ON THE EIR AND MSI LOOPS AND THE SSMIS MICROWAVE
IMAGE WITH GOOD CONFIDENCE. THE INITIAL INTENSITY HAS INCREASED TO
40 KTS BASED ON DVORAK INTENSITY ESTIMATES AND DOTSTAR SOUNDINGS.
UPPER- LEVEL ANALYSIS INDICATES A MARGINALLY CONDUCIVE ENVIRONMENT
AS NORTHERLY VERTICAL WIND SHEAR (VWS) HAS INCREASED TO MODERATE
LEVELS (25 TO 30 KNOTS) AND EQUATORWARD OUTFLOW REMAINS STRONG. TS
FUNG-WONG IS CURRENTLY TRACKING ALONG THE SOUTHWESTERN PERIPHERY OF
THE SUBTROPICAL RIDGE (STR) THAT IS POSITIONED TO THE NORTHEAST OF
THE SYSTEM.
3. FORECAST REASONING.
   A. THERE HAVE BEEN NO SIGNIFICANT CHANGES TO THE FORECAST
PHILOSOPHY SINCE THE LAST PROGNOSTIC REASONING.
   B. THROUGHOUT THE NEXT 24 HOURS, TS 16W WILL CONTINUE TO TRACK TO
THE NORTHWEST, GRAZING THE NORTHERN LUZON COAST, UNDER THE INFLUENCE
OF THE STR TO THE EAST.  A RIDGE CURRENTLY OVER SOUTHEASTERN CHINA
WILL CONTINUE TO RETROGRADE TO THE WEST AND WEAKEN, ALLOWING THE
SYSTEM TO TRACK TO THE NORTH AS THE STR TO THE EAST REORIENTS.
MODELS ARE IN GOOD AGREEMENT WITH A TRACK TOWARD TAIWAN THROUGH TAU
36.  HOWEVER, BEYOND TAU 36, MODELS CURRENTLY DEPICT TWO SCENARIOS.
THE NAVGEM, HWRF AND GFDN SOLUTIONS (THE WESTWARD GROUPING) SHOW THE
SYSTEM TURNING NORTHWESTWARD INTO THE TAIWAN STRAIT AFTER MAKING
LANDFALL IN TAIWAN. THE MAIN STEERING INFLUENCE IN THIS SCENARIO IS
A BUILDING HIGH TRANSITING FROM CENTRAL CHINA INTO THE YELLOW SEA,
WHICH FORCES THE SYSTEM WESTWARD ALONG ITS SOUTHERN PERIPHERY.  THE
JENS, JGSM AND GFS ENSEMBLE SOLUTIONS (THE NORTHWARD GROUPING) ALSO
SHOW THE CYCLONE TRACKING THROUGH TAIWAN, BUT CONTINUING TO TRACK
NORTH OF THE ISLAND INTO THE WESTERN EAST CHINA SEA. DUE TO THIS
BIFURCATION IN THE FORECAST, THERE IS LOW CONFIDENCE IN THE FORECAST
TRACK BEYOND TAU 48.
   C. IN THE EXTENDED TAUS, MODELS DEPICT THE TWO SEPARATE SCENARIOS
AS MENTIONED ABOVE, WITH THE WESTWARD GROUPING RUNNING THE SYSTEM
INTO CHINA NEAR SHANGHAI BEFORE THE SYSTEM TRACKS INTO THE WESTERLY
JET. THE MODELS IN THIS GROUPING AGREE ON A SLIGHT BREAK IN THE
PERSISTENT JET FEATURE AROUND TAU 120. HOWEVER, THE NORTHWARD MODEL
GROUPING DEPICTS FUNG-WONG TURNING AROUND A WEAKER STR INTO THE
WESTERLIES AROUND TAU 96 AND STARTING TO EMBED IN THE BAROCLINIC
ZONE BY THE END OF THE FORECAST PERIOD. THE OFFICIAL FORECAST IS
CONSISTENT WITH THE NORTHWARD GROUPING, WHICH INDICATES SLOWING
TRACK SPEED IN THE LATER TAUS FOLLOWED BY A TURN TO THE NORTHEAST
UNDER THE MIDLATITUDE WESTERLIES. DUE TO THE SIGNIFICANT DIFFERENCES
IN THE SPEED OF THE TRACK IN THE EXTENDED TAUS, THERE IS OVERALL LOW
CONFIDENCE IN THE FORECAST.//
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