Tropical Storm PEIPAH Advisory vie, 04-04

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 05W (FIVE) WARNING
NR 05//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION (TD) 05W (FIVE), LOCATED APPROXIMATELY 672 NM
EAST-SOUTHEAST OF KOROR, HAS TRACKED WEST-NORTHWESTWARD AT 07
KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY (MSI) DEPICTS A PARTIALLY EXPOSED LOW-LEVEL CIRCULATION
CENTER (LLCC) POSITIONED ON THE EASTERN EDGE OF A SYMMETRIC AREA OF
DEEP CONVECTION. A 032221Z SSMIS MICROWAVE IMAGE INDICATES SHALLOW
FRAGMENTED BANDING WRAPPING FROM THE NORTHERN QUADRANTS INTO THE
AREA OF DEEP CONVECTION SHEARED JUST WEST OF THE EXPOSED LLCC. THE
CURRENT POSITION IS BASED ON THE PARTIALLY EXPOSED LLCC IN THE MSI
WITH HIGH CONFIDENCE. THE CURRENT INTENSITY IS ASSESSED AT 30 KNOTS
BASED ON CONGRUENT DVORAK CURRENT INTENSITY ESTIMATES FROM PGTW,
KNES, AND RJTD. UPPER-LEVEL ANALYSIS INDICATES A MARGINALLY
FAVORABLE ENVIRONMENT CHARACTERIZED BY LOW TO MODERATE (10-20 KNOTS)
VERTICAL WIND SHEAR (VWS) AND GOOD DIVERGENCE ALOFT. ADDITIONALLY,
TD 05W IS CURRENTLY TRACKING OVER WARM SSTS (29 TO 30 CELSIUS) AND
HIGH VALUES OF OCEAN HEAT CONTENT (OHC). TD 05W IS CURRENTLY
TRACKING ALONG THE SOUTHERN PERIPHERY OF THE DEEP-LAYERED
SUBTROPICAL RIDGE (STR) TO THE NORTH.
3. FORECAST REASONING.
   A. TRACK SPEEDS IN THE JTWC FORECAST HAVE NOTABLY DECREASED AS
MULTIPLE CONSENSUS (CONW) MEMBERS HAVE SLOWED AND ADJUSTED FORECAST
TRACK SOLUTIONS. ADDITIONALLY, THE JTWC INTENSITY FORECAST HAS
NOTABLY CHANGED AS THE SYSTEM HAS STRUGGLED TO STAY VERTICALLY
STACKED AND IS NOW UNDER SIGNIFICANT SHEAR, EXPOSING THE LLCC. DUE
TO THIS AS WELL AS CHANGES TO DYNAMICAL AND STATISTICAL-DYNAMICAL
INTENSITY GUIDANCE, THE INTENSITY DEVELOPMENT RATE HAS SLOWED AND
THE PEAK INTENSITY HAS BEEN LOWERED TO 60 KNOTS AT TAU 120.
   B. TD 05W IS FORECAST TO TRACK WEST-NORTHWESTWARD WHILE GRADUALLY
INTENSIFYING THROUGH TAU 72. ALTHOUGH SST AND OHC VALUES WILL REMAIN
CONDUCIVE FOR DEVELOPMENT, THE SYSTEM WILL BE SUBJECT TO LOW TO
MODERATE VWS THROUGHOUT THE FORECAST TRACK AS WELL AS REMAIN SOUTH
OF THE STR AXIS UNDER DIFFLUENT EASTERLY FLOW. THIS MAY CAUSE THE
SYSTEM TO STRUGGLE TO ESTABLISH A STRONG OUTFLOW MECHANISM.
THEREFORE, TD 05W IS FORECAST TO INTENSIFY AT A SLOWER THAN
CLIMATOLOGICAL RATE. WITH THE EXCEPTION OF COAMPS-TC, WHICH TRACKS
THE SYSTEM WESTWARD, AVAILABLE DYNAMIC GUIDANCE REMAINS IN FAIR
AGREEMENT THROUGH TAU 48. HOWEVER, DESPITE THE GENERAL AGREEMENT ON
TRACK DIRECTION, THERE ARE SIGNIFICANT TRACK SPEED ISSUES INCLUDING
JGSM AND GFDN.
   C. AFTER TAU 48, THREE TRACK SCENARIOS EMERGE: COAMPS-TC
INDICATES A GENERALLY WESTWARD TRACK; CONW, GFS, ECMWF, AND JENS
INDICATE A WEST-NORTHWEST TRACK; AND NAVGEM AND EGRR INDICATE AN
EARLY RECURVE SCENARIO PRIOR TO PALAU. DUE TO THIS UNCERTAINTY, THE
JTWC FORECAST TRACK IS LAID CLOSE TO CONW AND HEDGED TOWARD GFS AND
ECMWF WHICH TRACK WEST-NORTHWESTWARD, EVENTUALLY TRACKING NEAR THE
ISLAND OF PALAU AND INTO THE EAST PHILIPPINE SEA. VWS IS EXPECTED TO
INCREASE SLIGHTLY, WHICH MAY ACT TO SLOW FURTHER DEVELOPMENT. THE
JTWC INTENSITY FORECAST HAS BEEN ADJUSTED AS DESCRIBED IN PARAGRAPH
3.A. DUE TO THE UNCERTAINTY AND GENERAL SPREAD IN OBJECTIVE
GUIDANCE, CONFIDENCE IN THE JTWC FORECAST TRACK REMAINS LOW.//
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