MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION TROPICAL DEPRESSION 06W (DANAS) WARNING NR 01// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL DEPRESSION (TD) 06W (DANAS), LOCATED APPROXIMATELY 587 NM SOUTH-SOUTHWEST OF KADENA AB, HAS TRACKED WEST-NORTHWESTWARD AT 12 KNOTS (KTS) OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS A BROAD CIRCULATION WITH DEEP CONVECTION DISPLACED TO THE WEST OF THE PARTLY OBSCURED LOW LEVEL CIRCULATION CENTER (LLCC) AND SHALLOW RAIN BANDS STARTING TO WRAP IN FROM THE SOUTH. THE INITIAL POSITION IS PLACED WITH POOR CONFIDENCE BASED ON THE BROAD CIRCULATION CENTER AS EVIDENCED IN THE MSI LOOP AND A PARTIAL 160529Z AMSR2 89 GHZ MICROWAVE IMAGE. OF NOTE, A 160021Z METOP-A AND 160135Z METOP-B ASCAT PASS CAUSED A SIGNIFICANT WESTWARD SHIFT IN THE 160000Z BEST TRACK POSITION AND THE WIND FIELD DEPICTED BY THOSE ASCAT PASSES SUGGESTED THAT THIS SYSTEM MAY BE BEGINNING TO TRANSITION FROM A MONSOON DEPRESSION INTO A TROPICAL CYCLONE. THE INITIAL INTENSITY OF 25 KTS IS CONSISTENT WITH THE KNES DVORAK INTENSITY OF T1.5 (25 KTS) AND THE AFOREMENTIONED ASCAT PASSES WHICH SHOWED 25-30 KT WINDS IN THE CONVECTION TO THE SOUTH AND WEST OF THE LLCC AND 10-20 KTS TO THE NORTHEAST. ENVIRONMENTAL CONDITIONS FOR TD 06W ARE MARGINAL WITH GOOD EQUATORWARD OUTFLOW AND WARM SEA SURFACE TEMPERATURE (30-31 CELSIUS) BEING OFFSET BY MODERATE TO STRONG VERTICAL WIND SHEAR (20-30 KTS). TD 06W IS TRACKING ALONG THE SOUTHWESTERN PERIPHERY OF A SUBTROPICAL RIDGE (STR). 3. FORECAST REASONING. A. THIS IS THE INITIAL PROGNOSTIC REASONING AND SETS THE FORECAST PHILOSOPHY. B. BY TAU 24, TD 06W SHOULD BE TRACKING MORE NORTHWARD AS IT ROUNDS THE STR AXIS. THE JTWC TRACK FORECAST CLOSELY FOLLOWS THE CONSENSUS TRACK BUT SPREAD IN THE MODEL TRACK GUIDANCE GROWS QUITE RAPIDLY, LIKELY DUE TO THE BROAD NATURE OF THE CIRCULATION. CONTINUED HIGH VWS WILL PREVENT TD 06W FROM INTENSIFYING SIGNIFICANTLY THROUGH TAU 48. AFTER TAU 48, SOMEWHAT IMPROVED ENVIRONMENTAL CONDITIONS ARE EXPECTED TO ALLOW SOME INTENSIFICATION TO 45 KTS AS TD 06W APPROACHES THE EAST COAST OF CHINA. THE JTWC INTENSITY FORECAST CLOSELY FOLLOWS THE INTENSITY GUIDANCE THROUGH TAU 48. AFTER TAU 48, THE MESOSCALE MODELS BRING TD 06W INLAND OVER CHINA, RENDERING THE INTENSITY GUIDANCE THOSE MODELS PROVIDE USELESS BASED ON THE JTWC TRACK FORECAST. AS A RESULT, BEYOND TAU 48 THE INTENSITY FORECAST IS BASED ON THE EXPECTATION THAT ENVIRONMENTAL CONDITIONS WILL BE MARGINALLY FAVORABLE. OVERALL, THERE IS LOW CONFIDENCE IN THIS PORTION OF THE JTWC TRACK FORECAST BASED ON LARGE SPREAD IN THE MODEL GUIDANCE AND HIGH UNCERTAINTY IN THE INITIAL POSITION. C. AFTER TAU 72, TD 06W IS EXPECTED TO CONTINUE TRACKING NORTHWARD ALONG THE WESTERN PERIPHERY OF THE STR, BRUSH THE EAST COAST OF CHINA, AND MOVE INTO THE YELLOW SEA WITH WEAK TROPICAL STORM FORCE WINDS. THE MODEL TRACK GUIDANCE HAS SIGNIFICANT SPREAD BETWEEN THE EASTERNMOST (GFS) AND WESTERNMOST (ECMWF AND GFS ENSEMBLE MEANS) MEMBERS. THE JTWC TRACK FORECAST CONTINUES TO FOLLOW THE CONSENSUS TRACK, WHICH CLOSELY FOLLOWS THE ECMWF, GALWEM, JGSM, AND NAVGEM SOLUTIONS. THE INTENSITY FORECAST ANTICIPATES SLIGHT WEAKENING AS THE SYSTEM BRUSHES THE CHINA COAST AND MOVES INTO THE YELLOW SEA BUT MAINTAINS THE INTENSITY AT WEAK TROPICAL STORM STRENGTH FOR THE DURATION OF THE EXTENDED FORECAST PERIOD. FOR THIS PORTION OF THE FORECAST, THERE IS LOW CONFIDENCE IN THE JTWC TRACK FORECAST DUE TO HIGH UNCERTAINTY IN THE MODEL GUIDANCE AND THE INITIAL POSITION OF THE SYSTEM.// NNNN NNNN