JTWC第18報的Prognostic Reasoning
WDPN33 PGTW 071500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 31W (HAIYAN) WARNING NR
18//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUPER TYPHOON 31W (HAIYAN), LOCATED APPROXIMATELY 543 NM EAST-
SOUTHEAST OF MANILA, PHILIPPINES, HAS TRACKED WEST-NORTHWESTWARD AT
22 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE
IMAGERY (EIR) REVEALS STY 31W HAS MAINTAINED A SHARPLY DEFINED EYE WITH
MULTIPLE CONCENTRIC RINGS AND A DEEP CONVECTIVE EYEWALL. A 071100Z
SSMIS MICROWAVE IMAGE REVEALS A STRONG FEEDER BAND WRAPPING ACROSS THE
NORTHWEST PERIPHERY OF THE SYSTEM AS WELL AS A DARK RING OF DEEP
CONVECTION OUTLINING THE COLD CLOUD-TOP TEMPERATURES WITHIN THE EYEWALL.
THE INITIAL POSITION IS BASED ON THE EYE FEATURE IN THE EIR ANIMATION
WITH HIGH CONFIDENCE. THE INITIAL INTENSITY IS BASED ON RECENT DVORAK
ESTIMATES FROM PGTW AND KNES INDICATING AN INTENSITY NEAR 170 KNOTS. SEA
SURFACE TEMPERATURES (SSTS) ALONG THE TRACK REMAIN VERY FAVORABLE
PROVIDING AMPLE SURFACE HEATING, SUPPORTING THE SUPER TYPHOON INTENSITY
OVER THE PAST FEW HOURS. UPPER LEVEL ANALYSIS INDICATES A FAVORABLE
ENVIRONMENT WITH NEAR-RADIAL OUTFLOW AND LOW (05 TO 10 KNOTS) VERTICAL
WIND SHEAR. STY 31W IS CURRENTLY TRACKING ALONG THE SOUTHERN PERIPHERY
OF THE DEEP-LAYERED SUBTROPICAL RIDGE (STR), WHICH IS ENTRENCHED TO THE
NORTH.
3. FORECAST REASONING.
A. NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
B. STY 31W IS EXPECTED TO MAINTAIN A WEST-NORTHWESTWARD TRACK ALONG
THE SOUTHERN EDGE OF THE STR, SHIFTING TO A NORTHWESTWARD TRACK BY
TAU 48. DUE TO THE EXTREMELY FAVORABLE ENVIRONMENTAL CONDITIONS AND
RECENT INTENSIFICATION, THE SYSTEM IS EXPECTED TO REMAIN AT SUPER
TYPHOON INTENSITY OVER THE NEXT 24 HOURS. LANDFALL WITH THE PHILIPPINES
IS ANTICIPATED NEAR TAU 12 AND WILL START TO IMPACT THE LOW LEVEL
INFLOW, LEADING TO A SLIGHT WEAKENING TREND THROUGH TAU 72. STY 31W WILL
TRACK INTO THE SOUTH CHINA SEA (SCS) WHERE SSTS BEGIN TO SLOWLY DECREASE,
AND SUBSEQUENTLY THE SURFACE HEAT POTENTIAL WILL NOT SUPPORT THE STRONGER
SUPER TYPHOON INTENSITIES.
C. IN THE EXTENDED TAUS, STY 31W IS FORECAST TO WEAKEN AFTER TAU
72 AS IT BEGINS TO ENCOUNTER LAND, WHICH WILL LEAD TO A MORE RAPID
WEAKENING OF THE LOW LEVEL STRUCTURE. DYNAMIC GUIDANCE REMAINS IN GOOD
AGREEMENT THROUGH THE EXTENDED TAUS AND ARE BEGINNING TO INDICATE A
RECURVE SCENARIO AS THE SYSTEM TRACKS OVER NORTHERN VIETNAM AND INTO
SOUTHERN CHINA; THEREFORE, THERE IS HIGH CONFIDENCE IN THE JTWC
FORECAST.//
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