Tropical Storm YUTU Advisory 10月22日

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 31W (THIRTYONE)
WARNING NR 02//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION 31W (YUTU), LOCATED APPROXIMATELY 764 NM
EAST-SOUTHEAST OF ANDERSEN AFB, HAS TRACKED WEST-NORTHWESTWARD AT
08 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED
SATELLITE IMAGERY SHOWS DEEP FLARING CONVECTION AROUND BUT
PREDOMINANTLY TO THE SOUTHWEST OF THE LOW-LEVEL CIRCULATION CENTER
(LLCC). THE INITIAL POSITION IS PLACED WITH FAIR CONFIDENCE BASED
ON A 211625Z SSMI 85GHZ MICROWAVE IMAGE. THE INITIAL INTENSITY IS
ASSESSED AT 30 KNOTS BASED ON DVORAK ESTIMATES OF T2.0 FROM KNES
AND RJTD AND T1.5 FROM PGTW. ENVIRONMENTAL ANALYSIS DEPICTS
EXCELLENT RADIAL OUTFLOW ONLY SLIGHTLY RESTRICTED TOWARD THE
NORTHWEST DUE TO A WEAK TUTT CELL.  SEA SURFACE TEMPERATURES ARE
HIGH (30 TO 32 DEGREES CELSIUS), VERTICAL WIND SHEAR REMAINS LIGHT
(5 TO 10 KNOTS), AND UPPER-TROPOSPHERIC OUTFLOW IS FORECAST TO
IMPROVE AS THE SYSTEM TRACKS TOWARD THE NORTHWEST AROUND THE
SOUTHWESTERN PERIPHERY OF THE SUBTROPICAL RIDGE (STR) LOCATED
TO THE NORTHEAST.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. THROUGH TAU 72, TD 31W WILL CONTINUE TRACKING TOWARD THE
NORTHWEST AROUND THE STR, WITH ENVIRONMENTAL CONDITIONS REMAINING
FAVORABLE FOR STEADY INTENSIFICATION. BY TAU 72, TD 31W WILL REACH
AN INTENSITY OF 110 KNOTS. DYNAMIC MODEL GUIDANCE IS IN GOOD
AGREEMENT THAT TD 31W WILL TRACK NORTHWESTWARD THROUGH TAU 72, SO
THERE IS HIGH CONFIDENCE IN THIS PORTION OF THE JTWC FORECAST
TRACK.
   C. BEYOND TAU 72, A WEAKNESS IN THE STR INDUCED BY AN UPPER-
TROPOSPHERIC TROUGH WILL GRADUALLY TURN TD 31W SLIGHLY MORE
POLEWARD. HOWEVER, THERE IS SIGNIFICANT SPREAD IN THE DYNAMIC MODEL
GUIDANCE IN THESE EXTENDED TAUS, WITH THE GFS-RELATED MODEL SUITE
(AVNO, AEMN, HWRF) RECURVING THE SYSTEM TOWARD THE NORTH AWAY FROM
THE MARIANAS. THE REST OF THE CONW GUIDANCE TRACKS THE SYSTEM
TOWARD AND THROUGH THE NORTHERN MARIANAS. ENVIRONMENTAL CONDITIONS
ARE EXPECTED TO REMAIN FAVORABLE FOR INTENSIFICATION, AND TD 31W IS
FORECAST TO REACH SUPER TYPHOON INTENSITY BY THE END OF THE
FORECAST PERIOD. DUE TO THE SIGNIFICANT SPREAD IN THE MODEL
GUIDANCE, THERE IS LOW CONFIDENCE IN THIS PORTION OF THE JTWC
FORECAST TRACK.//
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