Tropical Storm CEMPAKA Advisory 7月21日

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 10W (CEMPAKA) WARNING NR
010//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
   INITIAL POSITION: 21.7N 111.4E
   INITIAL INTENSITY: 55 KTS
   GEOGRAPHIC REFERENCE: 160 NM WEST-SOUTHWEST OF HONG KONG
   MOVEMENT PAST 6 HOURS: WESTWARD AT 05 KTS
   SIGNIFICANT WAVE HEIGHT: N/A
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) AND SURFACE REPORTS
CONFIRM TYPHOON 10W MADE LANDFALL NEAR YANGJIAN, CHINA AND IS
WEAKENING RAPIDLY. CLOUD TOPS ARE WARMING AND THE LOW LEVEL
CIRCULATION CENTER (LLCC) HAS BECOME OBSCURED. THE INITIAL POSITION
WAS ASSESSED WITH GOOD CONFIDENCE BASED ON SURFACE REPORTS AND GOOD
AGREEMENT BETWEEN JMA AND JTWC FIXES. THE VERY SHORT TIME THE
SYSTEM HAD BEEN ASHORE ALLOWED FOR PROJECTION OF PREVIOUS DVORAK
ASSESSMENTS WITH MODERATE CONFIDENCE ON THE INTENSITY, ALTHOUGH THE
SPARSE SURFACE REPORTS DID NOT CONFIRM OR REFUTE THE ASSESSMENT.
INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND
RADII).
CURRENT STEERING MECHANISM: TS 10W IS IN A VERY WEAK STEERING
ENVIRONMENT AT THE SOUTHEASTERNMOST EXTENT OF THE SUBTROPICAL RIDGE.
AGENCY DVORAK AND AUTOMATED FIXES:
   PGTW: NO CURRENT ESTIMATE
   RJTD: T3.5 - 55 KTS
FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY UNFAVORABLE
   VWS: 10-15 KTS
   SST: OVER LAND
   OUTFLOW: STRONG POLEWARD AND EQUATORWARD
   OTHER FACTORS: THE ONLY REASON THAT TS 09W IS NOT IN AN
EXCELLENT ENVIRONMENT FOR DEVELOPMENT IS THE PESKY FACT THAT IT IS
OVER LAND.
ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: MEDIUM
   INITIAL WIND RADII: NOT APPLICABLE
3. FORECAST REASONING.
SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.
FORECAST DISCUSSION: TS 09W WILL MAINTAIN A LOW LEVEL VORTEX AS IT
DOES A CYCLONIC LOOP OVER SOUTHEASTERNMOST CHINA. IT WILL RETURN TO
SEA OVER THE VERY WARM WATERS OF THE GULF OF TONKIN NEAR TAU 36,
THEN LOOP OVER HAINAN ISLAND BEFORE WHAT IS LEFT OF IT GOES BACK
INTO THE MONSOONAL SOUTHWESTERLIES THAT BLANKET THE SOUTH CHINA
SEA. THE FORECAST TURNS ON NUMEROUS SUBTELTIES, RANGING FROM
EXACTLY HOW LONG THE VORTEX REMAINS OVER LAND TO WHERE PRECISELY IT
ENTERS THE GULF OF TONKIN AND HOW MUCH IS LEFT OF IT AT THAT POINT,
TO HOW LONG IT SPENDS INTENSIFYING OVER THE GULF OF TONKIN, TO
EXACTLY WHAT TRACK IT TAKES OVER THE RUGGED TERRAIN OF HAINAN
ISLAND. UNFORTUNATELY ALL THESE FACTORS ARE SHORT TERM, WAIT AND
SEE ENDEAVORS THAT WILL REQUIRE VIGILANCE AND SHORT TERM
ADJUSTMENTS THAT MAY RESULT IN SHARP ADJUSTMENTS TO THE FORECAST.
JTWC IS CONTINUING TO TRACK AND ANALYZE THE STORM ON ITS OVERLAND
TRACK IN ANTICIPATION OF IT RE-ENTEERING THE GULF OF TONKIN.
MODEL DISCUSSION: THE AGREEMENT AND CONSISTENCY REGARDING THE
LOOPING TRACK AMONGST THE MULTI-MODEL CONSENSUS MEMBERS IS
REMARKABLE. OF COURSE, THE DIFFICULTY OF THE PROBLEM IS RESULTING
IN A WIDE DISPARITY OF BOTH INTENSITY AND SPEED OF ADVANCE OF THE
SYSTEM AMONGS THE CONSENSUS MEMEBERS, BUT THERE ARE NO OUTLIERS THAT
KILL THE STORM OVER LAND AND NONE THAT MISS HAINAN. THERE IS FAIR
CONFIDENCE IN THE OVERALL SCENARIO OF THE TRACK, AND VERY LOW
CONFIDENCE IN ALL OTHER
ASPECTS.
FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: LOW
   TRACK 72-120 HR: LOW
   INTENSITY 0 - 72 HR: LOW
   INTENSITY 72-120 HR: LOW//
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