MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 06W (DANAS) WARNING NR 04// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM 06W (DANAS), LOCATED APPROXIMATELY 255 NM NORTHEAST OF MANILA, PHILIPPINES, HAS TRACKED NORTHWARD AT 08 KNOTS OVER THE PAST SIX HOURS. THE CURRENT, HIGH-CONFIDENCE POSITION IS BASED ON A 170000Z PGTW SATELLITE FIX ON AN EXPOSED LOW-LEVEL CIRCULATION CENTER (LLCC) EVIDENT IN VISIBLE SATELLITE IMAGERY. THE INTENSITY OF 35 KNOTS IS CONSISTENT WITH SUBJECTIVE DVORAK INTENSITY ESTIMATES FROM MULTIPLE REPORTING AGENCIES, WHICH RANGE FROM 30 TO 35 KNOTS. TS 06W TURNED SHARPLY POLEWARD ALONG THE PERIPHERY OF A REORIENTING STEERING RIDGE TO THE EAST OVER THE PAST SIX HOUR. THE PRIMARY DEEP CONVECTION ASSOCIATED WITH THE SYSTEM HAS BEEN DISPLACED TO THE WEST OF THE LLCC BY PERSISTENT, MODERATE TO STRONG (20-25 KNOTS) EASTERLY VERTICAL WIND SHEAR (VWS). WARM SEA SURFACE TEMPERATURES AND WESTWARD AND EQUATORWARD DIFFLUENCE ALOFT REMAIN AS FAVORABLE OFFSETS TO THE VWS. 3. FORECAST REASONING. A. THE FORECAST TRACK HAS SHIFTED EASTWARD FROM THE PREVIOUS WARNING AND MEDIUM RANGE INTENSITIES HAVE INCREASED SLIGHTLY DUE TO LESS ANTICIPATED LAND INTERACTION. FORECAST WIND RADII HAVE ALSO EXPANDED A BIT BASED ON LOWER ANTICIPATED LAND INFLUENCE ON THE CIRCULATION. HOWEVER, THERE IS NO CHANGE TO THE OVERALL FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TS 06W WILL CONTINUE TRACKING GENERALLY POLEWARD THROUGHOUT THE NEXT 72 HOURS AS IT FOLLOWS THE PERIPHERAL FLOW ASSOCIATED WITH A REORIENTING SUBTROPICAL RIDGE TO THE EAST. SLOW INTENSIFICATION IS LIKELY IN THE NEAR-TERM AS VERTICAL WIND SHEAR OFFSETS THE FAVORABLE INFLUENCES OF PASSAGE OVER WARM WATER AND STRONG OUTFLOW ALOFT. THE NUMERICAL MODEL GUIDANCE PACKAGE HAS SHIFTED SLIGHTLY EASTWARD FROM THE PREVIOUS CYCLE, WITH THE ECMWF AND GFS SOLUTIONS BRACKETING THE SET OF FORECASTS AS THE WESTERNMOST AND EASTERNMOST SOLUTIONS, RESPECTIVELY. THE CURRENT FORECAST FOLLOWS THE MOST PROBABLE ORIENTATION OF THE LARGE-SCALE FLOW PATTERN, LIES SLIGHTLY TO THE EAST OF THE PREVIOUS JTWC FORECAST AND LIES SLIGHTLY TO THE WEST OF THE MULTI-MODEL CONSENSUS. THE LOW-LEVEL CIRCULATION PATTERN NEAR TS 06W REMAINS COMPLEX, WHICH IS INFLUENCING THE OUTCOME OF THE MODEL FORECASTS. GIVEN NOTED SPREAD IN THE GUIDANCE, CONFIDENCE IN THE JTWC TRACK FORECAST IS LOW. C. IN THE EXTENDED RANGE, TS 06W IS EXPECTED TO CONTINUE POLEWARD AND EASTWARD AND UNDERGO A SLOW EXTRATROPICAL TRANSITION AS IT ENCOUNTERS A DEVELOPING MID-LATITUDE TROUGH. SLIGHTLY WEAKENING IS ANTICIPATED, ALTHOUGH FAVORABLE BAROCLINIC INTERACTION WITH THE DEVELOPING TROUGH SHOULD ALLOW THE SYSTEM TO MAINTAIN GALE FORCE OR STRONGER WINDS THROUGHOUT THE TRANSITION. THE STORM TRACK DURING THE EXTENDED PERIOD IS HIGHLY DEPENDENT ON THE SOMEWHAT UNCERTAIN NEAR TO MEDIUM-TERM TRACK, SO CONFIDENCE IN THE EXTENDED PORTION OF THE FORECAST TRACK IS ALSO LOW.// NNNN NNNN