Tropical Storm YUTU Advisory 10月23日

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 31W (YUTU)
WARNING NR 06//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM 31W (YUTU), LOCATED APPROXIMATELY 209 NM NORTH-
NORTHEAST OF CHUUK, HAS TRACKED WEST-NORTHWESTWARD AT 12 KNOTS
OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR) SATELLITE
IMAGERY SHOWS AN EXPANSIVE AREA OF DEEP CONVECTION LOCATED DIRECTLY
OVER AND OCCLUDING THE LOW LEVEL CIRCULATION CENTER (LLCC). THE
CONVECTIVE STRUCTURE OF THE SYSTEM HAS IMPROVED SIGNIFICANTLY OVER
THE LAST SIX HOURS AS THE SYSTEM IS CURRENTLY UNDERGOING RAPID
INTENSIFICATION (RI). THE INITIAL POSITION IS PLACED WITH GOOD
CONFIDENCE BASED ON A 221747Z 91GHZ SSMI/S MICROWAVE IMAGE THAT
SHOWS EXTENSIVE CONVECTIVE BANDING IN THE EASTERN SEMI-CIRCLE
WRAPPING INTO THE LLCC. THE INITIAL INTENSITY OF 60 KNOTS IS HEDGED
ON THE UPPER END OF DVORAK CURRENT INTENSITY ESTIMATES OF T3.5 (55
KNOTS) FROM PGTW, KNES, AND RJTD. ENVIRONMENTAL ANALYSIS SHOWS THAT
TS 31W IS IN AN AREA OF LOW (10-15 KNOT) VERTICAL WIND SHEAR AND IS
TRACKING THROUGH WARM (30-32 CELSIUS) SEA SURFACE TEMPERATURES.
UPPER LEVEL ANALYSIS SHOWS THAT THE SYSTEM HAS A GOOD POLEWARD
OUTFLOW CHANNEL AND RADIAL OUTFLOW IN THE SOUTHERN SEMI-CIRCLE. TS
31W IS CURRENTLY RAPIDLY INTENSIFYING AS IT TRACKS NORTHWESTWARD
ALONG 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, TS 31W IS FORECAST TO CONTINUE TRACKING
NORTHWESTWARD ALONG THE SOUTHWESTERN EDGE OF THE STR TO THE
NORTHEAST. ENVIRONMENTAL CONDITIONS WILL REMAIN VERY FAVORABLE WITH
LOW VERTICAL WIND SHEAR AND HIGH SEA SURFACE TEMPERATURES COMBINING
WITH GOOD OUTFLOW TO ALLOW FOR CONTINUED RAPID INTENSIFICATION.
INTENSIFICATION TO 120 KNOTS WILL OCCUR BY TAU 72. DYNAMIC MODEL
GUIDANCE CONTINUES TO SHOW A GENERALLY NORTHWESTWARD TRACK THROUGH
TAU 72. MODEL GUIDANCE REMAINS IN GOOD AGREEMENT WITH A SMALL SPREAD
THROUGH TAU 72. DUE TO THE TIGHT GROUPING IN THE MODEL GUIDANCE,
THERE IS HIGH CONFIDENCE IN THIS PORTION OF THE JTWC FORECAST
TRACK.
   C. BEYOND TAU 72, TS 31W IS FORECAST TO CONTINUE TRACKING TO THE
NORTHWEST. ENVIRONMENTAL CONDITIONS WILL REMAIN FAVORABLE WITH LOW
TO MODERATE VERTICAL WIND SHEAR AND WARM SEA SURFACE TEMPERATURES.
THE ENVIRONMENT IS FORECAST TO BE FAVORABLE FOR ADDITIONAL
INTENSIFICATION, THOUGH NOT AT THE RAPID RATE AS SEEN IN THE NEAR
TERM FORECAST. DYNAMIC MODEL GUIDANCE BEGINS TO DIVERGE BEYOND TAU
72. THE PRINCIPLE NORTHERN OUTLIERS ARE THE GFS-ENSEMBLE AND COAMPS-
TC, WHICH FAVOR AN EARLY RECURVE TO THE NORTH EAST IMMEDIATELY AFTER
TAU 72. THE SOUTHERLY OUTLIER IS AFUM WHICH HAS THE SYSTEM TRACKING
TO THE WEST TOWARDS LUZON BY TAU 120. THE JTWC FORECAST TRACK IS
PLACED TO THE SOUTH OF THE MULTI-MODEL CONSENSUS TO OFFSET THE
INFLUENCE OF THE GFS-ENSEMBLE SINCE THE EARLY RECURVE IS UNLIKELY.
HOWEVER, DUE TO THE WIDE SPREAD IN MODEL GUIDANCE BY TAU 120 THERE
STILL IS LOW CONFIDENCE IN THIS PORTION OF THE JTWC FORECAST TRACK.//
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