Tropical Storm KOPPU Advisory 20 Οκτ.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 24W (KOPPU) WARNING NR
28//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 24W (KOPPU), LOCATED APPROXIMATELY 246 NM
NORTH-NORTHWEST OF MANILA, PHILIPPINES, HAS TRACKED NORTHWARD AT 04
KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE
IMAGERY DEPICTS A HIGHLY UNORGANIZED CONVECTIVE STRUCTURE DISPLACED
TO THE WEST OF A WEAK LOW LEVEL CIRCULATION CENTER (LLCC), WHICH MAY
ACTUALLY BE A MID-LEVEL FEATURE. A 191729Z NPP IMAGE SHOWS THE DEEP
CONVECTION TO THE SOUTHWEST OF THE LLCC, THE POSITION OF WHICH IS
LAID WITH MODERATE CONFIDENCE BASED ON THE 191834Z N-19 89 GHZ
IMAGE. THE INTENSITY IS ASSESSED AT 55 KNOTS BASED ON OVERALL
STRUCTURE OF THE SYSTEM AND SOME OBSERVATIONS OFF THE COAST OF
LUZON. UPPER LEVEL ANALYSIS INDICATES A MARGINAL ENVIRONMENT WITH 20
KNOTS OF EASTERLY VWS BEING PARTIALLY OFFSET BY DUAL CHANNEL
OUTFLOW. IN ADDITION, LAND INTERACTION CONTINUES TO IMPACT THE
ORGANIZATION OF THE LLCC. TS KOPPU IS TRACKING ALONG THE NORTHERN
SIDE OF A NER SOUTH OF THE SYSTEM AND AN INDUCED RIDGE BETWEEN TY
25W AND TS 24W.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE. OF NOTE, THE PREVIOUS 3 BEST TRACK
POSITIONS HAVE BEEN MOVED SIGNIFICANTLY FURTHER FROM THE LUZON
COASTLINE DUE TO THE DIFFICULTY IN THE POSITIONING OF THE SYSTEM
WHEN AS THE LLCC MAY BE MID-LEVEL AS THE SYSTEM TRACKED BACK OVER
WATER.
   B. TS 24W WILL SLOWLY TRACK EAST-NORTHEASTWARD, NORTH OF LUZON
OVER THE NEXT 36 HOURS AS THE NER IS THE MAIN STEERING MECHANISM.
DUE TO CONTINUED LAND INTERACTION AND INCREASED VWS, THE SYSTEM WILL
SLOWLY DECEASE IN INTENSITY THROUGH TAU 72. BEYOND TAU 36, THE NER
WILL TRACK TO THE WEST, PROMOTING THE INDUCED RIDGE TO BECOME THE
MAIN STEERING MECHANISM, FORCING A POLEWARD COMPONENT TO THE TRACK.
   C. IN THE EXTENDED TAUS, TS KOPPU WILL CONTINUE TO TRACK POLEWARD
ALONG THE WESTERN PERIPHERY OF THE BUILDING STR. THE SYSTEM WILL
SLOWLY INTENSIFY AS IT TRACKS OVER WARM SSTS WITH GOOD DIVERGENT
OUTFLOW. DYNAMIC MODEL GUIDANCE IS WIDELY SPREAD BEYOND TAU 24 WITH
SOME TRACKERS FOLLOWING THE VORTEX TO THE WEST TOWARDS SOUTHERN
CHINA. HOWEVER, THE MAJORITY OF TRACKERS HAVE THE SYSTEM TRACKING TO
THE EAST AND POLEWARD, SPREADING FROM THE EASTERN COAST OF TAIWAN TO
EAST OF THE RYUKYU ISLAND CHAIN. DUE TO THE COMPLEX STEERING
ENVIRONMENT AND THE CONTINUED SPREAD OF MODEL GUIDANCE, THERE IS LOW
CONFIDENCE IN THE JTWC FORECAST TRACK WHICH IS POSITIONED NEAR THE
MULTI-MODEL CONSENSUS.//
NNNN
NNNN