FYI: JTWC Analysis-(Supplementary Info) WDPN31 PGTW 062100 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 05W (PEIPAH) WARNING NR 16// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL DEPRESSION (TD) 05W (PEIPAH), LOCATED APPROXIMATELY 25 NM EAST-SOUTHEAST OF KOROR, PALAU, HAS TRACKED NORTHWESTWARD AT 12 KNOTS OVER THE PAST SIX HOURS. THE CURRENT POSITION IS BASED ON A RECENT PGTW SATELLITE FIX, A 061701Z AMSU PASS, AND SYNOPTIC OBSERVATIONS FROM KOROR. THE INTENSITY OF 30 KNOTS IS CONSISTENT WITH DVORAK CURRENT INTENSITY ESTIMATES FROM PGTW AND RJTD AND OBSERVATIONS FROM KOROR. MOST DEEP CONVECTION ASSOCIATED WITH TD 05W REMAINS SHEARED WELL TO THE WEST OF THE EXPOSED LOW LEVEL CIRCULATION CENTER DUE TO STRONG EASTERLY FLOW ALOFT. THE SYSTEM CONTINUES TO TRACK GENERALLY WESTWARD ALONG THE SOUTHERN PERIPHERY OF A ZONALLY-ORIENTED SUBTROPICAL RIDGE TO THE NORTH. 3. FORECAST REASONING. A. DUE TO PERSISTENT VERTICAL WIND SHEAR AND TRENDS IN STATISTICAL-DYNAMICAL INTENSITY GUIDANCE, FORECAST INTENSITIES HAVE BEEN REDUCED FROM THE PREVIOUS WARNING. TRACK SPEEDS HAVE ALSO BEEN REDUCED FOR THE TAU 36 TO TAU 72 PERIOD CONSISTENT WITH A SLOWDOWN IN CONSENSUS TRACK GUIDANCE. B. TD 05W IS FORECAST TO TRACK WEST-NORTHWESTWARD UNDER THE CONTINUED INFLUENCE OF THE SUBTROPICAL STEERING RIDGE. SIGNIFICANT INTENSIFICATION DURING THE FORECAST PERIOD IS UNLIKELY. HOWEVER, A SLIGHT RELAXATION OF VERTICAL WIND SHEAR AND IMPROVED POLEWARD OUTFLOW INDUCED BY A MIDLATITUDE TROUGH PASSING TO THE NORTH MAY ENABLE TD 05W TO MINIMALLY INTENSIFY AROUND TAU 48. DISSIPATION IN THE NEAR TO MEDIUM TERM IS ALSO POSSIBLE, ALTHOUGH IT APPEARS AT THIS POINT THAT SUFFICIENT UPPER LEVEL OUTFLOW AND PASSAGE OVER WARM WATER WILL ALLOW THE SYSTEM TO MAINTAIN INTENSITY AT OR ABOVE THE WARNING THRESHOLD OF 25 KNOTS. C. TD 05W WILL MOVE OVER LAND AND WEAKEN AFTER TAU 72. THERE IS GENERALLY GOOD AGREEMENT AMONG NUMERICAL MODELS REGARDING TRACK DIRECTION, BUT A FEW MODELS INCLUDING GFS AND ECMWF NOW SUGGEST A PRONOUNCED SLOWING OF TRACK MOTION BETWEEN TAU 36 AND TAU 48 AS THE AFOREMENTIONED MIDLATITUDE TROUGH PASSES TO THE NORTH. HOWEVER, MODEL FORECAST AGREEMENT IS CLOSE ENOUGHT TO LEND HIGH CONFIDENCE TO THE JTWC TRACK FORECAST TRACK.// NNNN- with Gov Joey Sarte Salceda
Posted on: Mon, 07 Apr 2014 00:19:29 +0000
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