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;P升至MEDIUM;P
THE AREA OF CONVECTION PREVIOUSLY LOCATED NEAR 23.0N
178.5E, IS NOW LOCATED NEAR 25.0N 178.5E, APPROXIMATELY 290 NM
SOUTHWEST OF MIDWAY. ANIMATED MULTISPECTRAL SATELLITE IMAGERY SHOWS
AN AREA OF FLARING CONVECTION AROUND THE NORTHERN PERIPHERY OF A
WELL-DEFINED LOW-LEVEL CIRCULATION CENTER (LLCC). UPPER-LEVEL
ANALYSIS INDICATES THAT THE LLCC LIES SOUTHEAST OF A TROPICAL UPPER
TROPOSPHERIC TROUGH CELL, WHICH IS PROVIDING STRONG (20 TO 30
KNOTS) WESTERLY VERTICAL WIND SHEAR. UPPER LEVEL DIVERGENT FLOW TO
THE NORTHEAST AIDED IN THE MOST RECENT FLARE UP OF CONVECTION AND
HAS RESULTED IN A SLIGHTLY MORE FAVORABLE ENVIRONMENT FOR
DEVELOPMENT. THE 091958Z 91 GHZ SSMIS MICROWAVE IMAGE DEPICTS
INCREASED CONVECTION BEGINNING TO WRAP AROUND THE NORTHWESTERN
QUADRANT AND DEPICTS A FULLY-EXPOSED LLCC. A 090058Z PARTIAL
OCEANSAT PASS SHOWS A FAIRLY SYMMETRICAL LLCC, WITH SOME 20 KNOT
WIND BARBS ON THE NORTHERN PERIPHERY, AND 10 TO 15 KNOTS TO THE
SOUTH AND WEST. CURRENTLY THERE ARE NO AMSU CROSS-SECTIONS
AVAILABLE TO EVALUATE THE CORE TEMPERATURE CHARACTERISTICS OF THIS
DISTURBANCE BUT PHASE SPACE MODEL OUTPUT SUGGESTS IT IS A SHALLOW
WARM-CORE WHICH WILL TRANSITION TO A COLD-CORE SYSTEM OVER THE NEXT
FEW DAYS. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 15 TO 20
KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1009 MB.
DUE TO THE INCREASINGLY FAVORABLE UPPER LEVEL ENVIRONMENT AND
ASSOCIATED INCREASE IN CONVECTION, THE POTENTIAL FOR THE
DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24
HOURS IS UPGRADED TO MEDIUM. |
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