WDPN32 PGTW 300300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 23W (ATSANI) 
WARNING NR 003//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION 23W (ATSANI), LOCATED APPROXIMATELY 214 NM 
SOUTH-SOUTHEAST OF ANDERSEN AFB, GUAM HAS TRACKED NORTHWESTWARD AT 
16 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED MULTISPECTRAL 
SATELLITE IMAGERY DEPICTS A BROAD AREA OF GENERALLY DISORGANIZED 
DEEP CONVECTIVE ACTIVITY WITH A LARGE AREA OF CONVECTION THAT HAS 
MOVED SWIFTLY NORTHWESTWARD OVER THE PAST THREE HOURS. A 292342Z 
ASCAT-C PASS INDICATES A CIRCULATION TO THE SOUTHEAST OF THE BULK OF 
THIS CONVECTION AND A 292317Z ASCAT-A IMAGE INDICATES A SHARP WAVE 
WITH THIS CONVECTIVE MASS, INDICATING THAT THERE IS NOT ONE DISCRETE 
LOW-LEVEL CIRCULATION CENTER (LLCC). DUE TO THESE MULTIPLE AREAS OF 
CIRCULATION THERE IS A HIGH DEGREE OF UNCERTAINTY IN THE INITIAL 
PLACEMENT AS THE LLCC IS NOT FIRMLY ESTABLISHED AND MAY SHIFT. THE 
INITIAL INTENSITY IS ASSESSED AT 30 KTS BASED ON SUBJECTIVE DVORAK 
ESTIMATES. UPPER LEVEL ANALYSIS INDICATES STRONG (20-25 KNOT) 
VERTICAL WIND SHEAR OVER THE SYSTEM MAY BE HAMPERING DEVELOPMENT, 
HOWEVER, THIS IS PARTIALLY OFFSET BY EQUATORWARD OUTFLOW ALOFT AND 
30 TO 31 DEGREE CELSIUS SEA SURFACE TEMPERATURES. TD 23 IS CURRENTLY 
TRACKING GENERALLY NORTHWESTWARD ALONG A SUBTROPICAL RIDGE (STR) OF 
HIGH PRESSURE TO THE NORTHEAST.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS 
PROGNOSTIC REASONING MESSAGE.
   B. TD 23W IS FORECAST TO CONTINUE TRACKING NORTHWESTWARD, 
TRACKING ALONG THE STR TO THE NORTHEAST FOLLOWING THE 850-700MB 
HEIGHTS. AS THE SYSTEM TRACKS NORTHWESTWARD, IT WILL CONTINUE TO BE 
IMPACTED BY THE OUTFLOW FROM TY 22W, WITH CONVERGENT UPPER-LEVEL 
FLOW MOVING DOWN FROM THE NORTH LIMITING THE AVAILABLE OUTFLOW TO A 
SINGLE EQUATORWARD CHANNEL. THIS, COMBINED WITH MODERATE VWS (15-20 
KTS) WILL OFFSET THE VERY WARM (30 DEG CELSIUS) WATERS TO LIMIT THE 
SYSTEM?S INTENSIFICATION THROUGH TAU 48. AFTER TAU 48 THE UPPER-
LEVEL PATTERN WILL BEGIN TO SHIFT AND PROVIDE INCREASING DIVERGENT 
OUTFLOW ALLOWING THE SYSTEM TO CONTINUE INTENSIFYING INCREASING TO 
70 KNOTS BY TAU 72. THERE ARE CURRENTLY TWO DIFFERENT MODEL 
SOLUTIONS WITH GFS AND ECMWF TAKING THE SOUTHERN TRACK THAT 
CONTINUES TRACKING NORTHWESTWARD, WHEREAS NAVGEM AND GALWEM RECURVE 
THE SYSTEM AFTER TAU 36. AS THE SOLUTIONS CONTINUE TO DIVERGE THE 
JTWC FORECAST TRACK HAS BEEN PLACED IN AGREEMENT WITH GFS AND ECMWF 
AND IS PLACED WITH LOW CONFIDENCE AS THERE ARE MULTIPLE SOLUTIONS 
AMONGST THE MODELS. THE JTWC INTENSITY FORECAST HEDGES JUST SLIGHTLY 
ABOVE THE MULTI-MODEL CONSENSUS WITH FAIR CONFIDENCE. 
   C. BEYOND TAU 72, THE SYSTEM WILL SLOW DOWN AS IT TRACKS TOWARDS 
A COL AREA AND LOSES THE STRONG STEERING MECHANISM. AS IT TRACKS 
NORTHWESTWARD IT BEGINS TO TAP INTO DUAL-CHANNEL OUTFLOW, ALLOWING 
IT TO INTENSIFY TO 100 KNOTS AT TAU 120. THE JTWC TRACK CONTINUES TO 
FOLLOW THE GFS AND ECMWF SOLUTION WITH LOW CONFIDENCE SINCE THERE IS 
ALSO A RECURVING SOLUTION THAT NAVGEM AND GALWEM TAKE. THE JTWC 
INTENSITY FORECAST CONTINUES TO HEDGE JUST SLIGHTLY ABOVE THE MULTI-
MODEL CONSENSUS WITH FAIR CONFIDENCE. //
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