| DPN33 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.// NNNN |