Tropical Storm USAGI Advisory 11月23日

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 33W (USAGI)
WARNING NR 19//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM 33W (USAGI), LOCATED APPROXIMATELY 401 NM EAST
OF HO CHI MINH CITY, VIETNAM, HAS TRACKED WEST-SOUTHWESTWARD AT
08 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED
(EIR) SATELLITE IMAGERY DEPICTS A CONSOLIDATING SYSTEM WITH
IMPROVED DEEP CONVECTIVE BANDING WRAPPING INTO FLARING CENTRAL
CONVECTION OBSCURING A DEFINED LOW-LEVEL CIRCULATION CENTER
(LLCC). THE INITIAL POSITION IS BASED WITH FAIR CONFIDENCE ON
INFLOW INTO THE OBSCURED LLCC IN THE EIR LOOP, SUPPORTED BY A
221740Z ATMS 88.2GHZ IMAGE THAT SHOWS DEEP CONVECTIVE BANDING
WRAPPING INTO THE CENTER. A 221405Z ASCAT IMAGE REVEALED A
COMPACT SYSTEM WITH 30 AND 35 KT WIND BARBS CLOSE TO THE
CENTER. THE INITIAL INTENSITY IS BASED ON THE ASCAT PASS AND THE
KNES AND PGTW DVORAK CURRENT INTENSITY ESTIMATES OF T2.5 (35
KTS), IN AGREEMENT WITH THE 221710Z AUTOMATED DVORAK TECHNIQUE
ESTIMATE OF 35 KTS. UPPER-LEVEL ANALYSIS REVEALS A FAVORABLE
ENVIRONMENT WITH LOW VERTICAL WIND SHEAR AND STRONG POLEWARD AND
EQUATORWARD DIVERGENCE. TS 33W IS CURRENTLY TRACKING ALONG THE
SOUTHERN PERIPHERY OF A SUBTROPICAL RIDGE (STR) POSITIONED TO
THE NORTH AND HAS SLOWED OVER THE PAST 6 HOURS.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TS 33W WILL CONTINUE WEST-SOUTHWESTWARD THROUGH TAU 24 AS
IT ENCOUNTERS INCREASING NORTHEASTERLY FLOW ASSOCIATED WITH A
LOW-LEVEL STR FORECAST TO BUILD OVER SOUTHEAST ASIA. TS 33W IS
EXPECTED TO INTENSIFY UNDER FAVORABLE UPPER LEVEL CONDITIONS AND
WARM (26-28 DEGREES CELSIUS) SEA SURFACE TEMPERATURES TO A PEAK
INTENSITY OF 50 KNOTS BY TAU 36; HOWEVER, LOW-LEVEL
NORTHEASTERLY WINDS ARE ADVECTING COLDER AIR INTO THE REGION AND
WILL LIMIT INTENSIFICATION POTENTIAL ANY FURTHER. NEAR TAU 48,
THE SYSTEM WILL MAKE LANDFALL ALONG THE SOUTHEAST COAST OF
VIETNAM AND WILL RAPIDLY DISSIPATE BY TAU 72 AS IT TRACKS ACROSS
SOUTHERN VIETNAM. COAMPS-NAVGEM IS THE SOUTHERNMOST OUTLIER AND
KEEPS 33W MOSTLY OVER WATER, THUS PREDICTING AN ERRONEOUS AND
UNLIKELY INTENSIFICATION PERIOD IN LATER TAUS WHEN MOST OTHER
MODEL TRACKS KEEP THE SYSTEM OVER LAND FOR AT LEAST 48 HOURS,
AND SOME, INCLUDING GFS AND ECMWF, CURVE 33W TOWARDS THE
NORTHWEST AND KEEP IT OVER LAND INDEFINITELY. ECMWF AND THE BULK
OF THE REMAINING MODELS ARE SOUTH OF THE MULTI-MODEL CONSENSUS
UNTIL AFTER TAU 72, WHEN ECMWF AND GFS CURVE TO THE NORTH, AND
THE MULTI-MODEL CONSENSUS CONTINUES DUE WEST INTO THE GULF OF
THAILAND. THE JTWC FORECAST TRACK IS PLACED BETWEEN CONSENSUS
AND THE ECMWF AND GFS SOLUTIONS, FAVORING A TURN TO THE
NORTHWEST AND DISSIPATION OVER LAND BY TAU 72, WITH HIGH
CONFIDENCE.//
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