Tropical Storm SURIGAE Advisory 4月22日

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 02W (SURIGAE) WARNING NR 034//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 02W (SURIGAE), LOCATED APPROXIMATELY 356 NM
NORTHEAST OF MANILA, PHILIPPINES, HAS TRACKED NORTHWARD AT 05 KNOTS
OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR) IMAGERY
STILL SHOWS A VIGOROUS SYSTEM WITH A BROAD, 50NM EYE AND A CLOUD
SHIELD THAT IS BEGINNING TO STRETCH TO THE NORTHEAST AS IT FEELS THE
EFFECTS OF VIGOROUS UPPER LEVEL WESTERLIES. PGTW AND FMEE FIXES ARE
IN GOOD AGREEMENT WITH DATA T NUMBERS ASSESSED AT T4.5 AND FINAL
CURENT INTENSITY ESTIMATES CONSTRAINED TO T5.5 (102KTS). CLOUD TOPS
ARE VISIBLY WARMING AND WATER VAPOR ANIMATION SHOWS A SHARPENING
EDGE AS SUBSIDENCE ENCROACHES ON THE NORTHWEST QUANDRANT. A GFS
CROSS SECTION OF THE STORM DEPICTS A SHARP DRY LINE OVER THE TAIWAN
STRAIT. THE AXIS OF DEEP MOISTURE HAS NOW SHIFTED TO A SOUTHWEST
THROUGH NORTHEAST BEARING, INDICATING THE BEGINNINGS OF A TRANSITION
TO ASYMMETRY. TY SURIGAE IS TRACKING ALONG THE WESTERN PERIPHERY OF
A SUBTROPICAL RIDGE (STR) AND HAS CROSSED A SIGNIFICANT CHECKPOINT
DURING THE PAST SIX HOURS AS IT ROUNDED THE STR AXIS AND IS NOW
CLEARLY BEGINNING TO APPROACH THE MID-LATITUDES.
   A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY
SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TY SURIGAE WILL CONTINUE TO THE NORTHEAST AND CONTINUE GAINING
LATITUDE DURING THE NEXT 48 HOURS, WEAKENING AND STRETCHING AS IT
DOES SO. TWO MID-LATITUDE TROUGHS WILL AFFECT THE SYSTEM IN THE NEAR
TERM. THE FIRST WILL PASS NORTH OF TY SURIGAE AS IT TRACKS SOUTH OF
OKINAWA. THE TROUGH WILL STRETCH BUT NOT PICK UP THE SYSTEM, AND AS
THE TRAILING SHORT-WAVE RIDGE BUILDS IN BEHIND IT. AS THIS RIDGE
BUILDS, IT WILL NUDGE THE SYSTEM TO THE SOUTH BETWEEN TAU 48 AND 72.
TRACK GUIDANCE IS TIGHT THROUGH TAU 72 (NEAR THE 135TH MERIDIAN),
THEN BEGINS TO SPREAD AND VARY IN ALONG-TRACK SPEEDS DURING THE
PROCESS OF ABSORPTION INTO THE THICKNESS RIBBON (BAROCLINIC ZONE).
STEADY DETERIORATION OF THE SYSTEM WILL THEN BEGIN. INTENSITY
GUIDANCE ALSO CONSOLIDATED IN THE LATEST ITERATION, SHOWING A STEADY
AND LINEAR DECLINE THROUGH THE FIRST 72 HOURS. THE INTENSITY
FORECAST IS PLACED IN THE MIDDLE OF THE GUIDANCE PACKAGE. THERE
IS GOOD CONFIDENCE IN BOTH TRACK AND INTENSITY FORECAST THROUGH THE
FIRST 72 HOURS WHILE THE LACK OF RECENT SCATTEROMETRY AND THE
PENDING EXPANSION OF THE WINDFIELDS BY THE UPPER LEVEL TROUGHS MAKE
FOR CONSIDERABLY LESS CONFIDENCE IN THE WIND RADII.
   C. BY TAU 96 A SECOND, DEEPER SHORT WAVE THAT IS CURRENTLY
TRACKING OVER THE GOBI DESERT WILL PICK UP THE SYSTEM AND CAUSE TY
SURIAGE TO BEGIN EXTRA-TROPICAL TRANSITION (ETT) IN EARNEST. MODEL
GUIDANCE HAS CRYSTALLIZED REGARDING THE FORMATION OF AN EXTRA
TROPICAL CYCLONE COMPLETING NEAR OR JUST AFTER TAU 120. THE
DETERMINISTIC GFS SOLUTION, HOWEVER, CONTINUES TO DEPICT AN
ALTERNATE SCENARIO WHERE VIGOROUS WESTERLIES DECAPITATE THE SYSTEM
AND LEAVE A WEAK, LOW LEVEL VORTEX MEANDERING BETWEEN THE 20TH AND
25TH LATITUDE BETWEEN TAU 96 AND 120. A MORE STANDARD CASE OF
ABSORPTION INTO THE BAROCLINIC ZONE AND TRANSITION TO A MID-LATITUDE
LOW IS BECOMING MORE CONVINCING BASED ON THE MODEL GUIDANCE. PHASE
BASED GUIDANCE IS UNANIMOUS AND DEPICTS TRANSITION TO A COLD CORE
LOW WITH THE EXCEPTION OF GFS WHICH HOLDS THE SYSTEM AS A WARM CORE
CYCLONE THROUGH DISSIPATION. BASED ON THE PREPONDERANCE OF GUIDANCE,
THE JTWC FORECAST IS BASED ON THE ETT SCENARIO, ALBEIT WITH LOWER
CONFIDENCE THAN DESIRED GIVEN THE RECENT OUTSTANDING PERFORMANCE OF
THE GFS MODEL. THE HEARTENING NEWS IS THAT EVEN IF THE GFS SOLUTION
DOES MANIFEST, THE LEFTOVER LOW LEVEL VORTEX WILL BE SO WEAK AND FAR
FROM LAND AS TO BE INCONSEQUENTIAL. THE JTWC TRACK STAYS VERY TIGHT
WITH CONSENSUS THROUGH TAU 96, THEN IS HEDGED TO THE SOUTH OF
CONSENSUS IN THE LAST 24 HOURS, TOWARDS THE ECMWF AND JGSM TRACK
GUIDANCE. THE INTENSITY FORECAST REMAINS IN THE MIDDLE OF THE MODEL
GUIDANCE ENVELOPE THROUGHOUT THE FORECAST. A BRIEF BUMP IN INTENSITY
WILL OCCUR AS IT FUSES WITH THE BAROCLINIC ZONE AND BECOMES A
VIGOROUS STORM FORCE LOW WHILE TRACKING TO THE SOUTHEAST OF IWO TO.//
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