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While the Philippines escaped the wrath of Typhoon Lupit, Tropical Storm 23W is developing well east of the Philippines and the Joint Typhoon Warning Center forecast not only develops it into Typhoon Mirinae, but also makes the storm intensity 100 kts as it moves into the Philippines almost due east of Manila at 12Z on October 31. The ridge that had broken down enough to allow Lupit to scamper to the northeast, away from the Philippines has filled back in and is growing stronger. As we saw with Typhoon Lupit, with several days before projected landfall, there can be many changes to the environment and also the steering currents. So, this is not to be taken as Gospel. However, the reasoning is sound and the storm is already developing and moving faster than intially anticipated. The Philippines will certainly be on guard as any tropical cyclone activity in the region that remotely threatens the country needs to be taken seriously given the region will be slow to recover from the effects of Typhoon Parma and Tropical Storm Ketsana. Developing Tropical Storm 23W will be affecting Andersen Air Force Base, south of Saipan, by 00Z October 27.
WDPN32 PGTW 261500 MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 23W (TWENTYTHREE) WARNING NR 03// RMKS/ 1. FOR METEOROLOGISTS. 2. 12 HOUR SUMMARY AND ANALYSIS. A. TROPICAL STORM (TS) 23W CONSOLIDATED FURTHER AS IT TRACKED AT A FASTER THAN NORMAL RATE WEST-NORTHWESTWARD ALONG THE SOUTHERN PERIPHERY OF THE MID-LEVEL SUBTROPICAL RIDGE TO THE NORTH. ANIMATED INFRARED IMAGERY SHOWS AN INCREASE IN DEEP CONVECTION NEAR THE LOW LEVEL CIRCULATION CENTER. THE CURRENT POSITION IS BASED ON SATELLITE IMAGERY ANIMATION AND EXTRAPOLATED FROM A 260918Z SSMIS MICROWAVE PASS. THE CURRENT INTENSITY IS BASED ON DVORAK ESTIMATES FROM PGTW AND KNES OF T2.5. UPPER LEVEL ANALYSIS INDICATES THE SYSTEM IS JUST SOUTH OF THE SUBTROPICAL RIDGE AXIS IN AN AREA OF LOW VERTICAL WIND SHEAR. A 260000Z PGUM UPPER-AIR SOUNDING REPORTING EAST-NORTHEAST WINDS FROM THE SURFACE THROUGH 400 MB SUPPORTS CURRENT AND PROJECTED STORM MOTION. ANIMATED WATER VAPOR IMAGERY SHOWS A GOOD POLEWARD OUTFLOW ENHANCED BY THE TROPICAL UPPER TROPOSPHERIC TROUGH TO THE NORTHEAST. 3. FORECAST REASONING A. THERE IS NO SIGNIFICANT CHANGE TO THE PREVIOUS BULLETIN. B. TS 23W WILL CONTINUE TO TRACK WEST-NORTHWESTWARD AS DESCRIBED IN PARA 2.A. THE STORM IS ALSO EXPECTED TO STEADILY INTENSIFY TO TYPHOON STRENGTH BY TAU 72, AS THE ENVIRONMENTAL CONDITIONS WILL REMAIN FAVORABLE FOR DEVELOPMENT. C. AFTER TAU 72, TS 23W IS EXPECTED TO CONTINUE INTENSIFYING, UP TO 100 KNOTS, AS IT TRACKS OVER THE WARM SEA SURFACE TEMPERATURES OF THE PHILIPPINE SEA WITH GOOD POLEWARD OUTFLOW AND MINIMAL VERTICAL WIND SHEAR. THE AVAILABLE MODEL GUIDANCE IS IN GOOD AGREEMENT WITH A WESTWARD TRACK TOWARDS THE PHILIPPINES. THIS TRACK FORECAST IS LEFT OF THE JTWC CONSENSUS AND TRACKS THE STORM BETWEEN GUAM AND SAIPAN. WBAR REMAINS RIGHT OF THE ENVELOPE AND EGRR STARTS TO THE LEFT UP TO TAU 72 BEFORE IT VEERS TOWARDS THE MAIN PACK.// NNNN