Tropical Storm CHAMPI Advisory mer, 14.10.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 25W (TWENTYFIVE)
WARNING NR 04//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION (TD) 25W (TWENTYFIVE), LOCATED APPROXIMATELY
733 NM EAST OF SAIPAN, CNMI, HAS TRACKED WEST-NORTHWESTWARD AT 14
KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY (MSI) SHOWS THE SYSTEMS CONVECTIVE SIGNATURE HAS NOT CHANGED
EVEN AS THE LOW LEVEL CIRCULATION CENTER (LLCC) HAS BECOME FULLY
EXPOSED. THE INITIAL POSITION IS BASED ON THE MSI LOOP WITH HIGH
CONFIDENCE. THE INITIAL INTENSITY OF 30 KNOTS IS BASED ON AN OVERALL
ASSESSMENT OF DVORAK ESTIMATES AND REFLECTS THE SUSTAINED SIGNATURE
OF THE SYSTEM. UPPER LEVEL ANALYSIS INDICATES THE SYSTEM IS IN A
MARGINALLY-FAVORABLE ENVIRONMENT WITH 15 TO 20 KNOT EASTERLY VERTICAL
WIND SHEAR (VWS) BEING PARTIALLY OFFSET BY STRONG DIVERGENT OUTFLOW.
TD 25W IS TRACKING WESTWARD ALONG THE SOUTHERN PERIPHERY OF THE
SUB-TROPICAL RIDGE (STR) TO THE NORTH.
3. FORECAST REASONING.
   A. NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TD 25W WILL TRACK WEST-NORTHWESTWARD UNDER THE INFLUENCE OF THE
STEERING STR THROUGHOUT THE FORECAST PERIOD. ENVIRONMENTAL CONDITIONS
WILL REMAIN MARGINALLY-FAVORABLE LEADING TO A SLIGHT INTENSIFICATION
THROUGH TAU 48. SEA SURFACE TEMPERATURES WILL INCREASE AND VWS WILL
SLIGHTLY DECREASE AS THE CYCLONE APPROACHES GUAM ALLOWING THE
INTENSIFICATION RATE TO INCREASE.
   C. BEYOND TAU 72, TD 25W WILL CONTINUE TO TRACK ON A WEST-
NORTHWESTWARD TRAJECTORY. AS THE SYSTEM GAINS LATITUDE, VWS WILL
INCREASE AND SSTS WILL DECREASE. HOWEVER, THE ADDITION OF A STRONG
POLEWARD OUTFLOW CHANNEL WILL OFFSET THESE NEGATIVE EFFECTS, BRINGING
25W TO 85 KNOTS BY END OF FORECAST. THE MODEL GUIDANCE IS IN FAIR
AGREEMENT IN THE NEAR TERM FOLLOWED BY A LARGE SPREAD IN THE LONG
TERM FORECAST. THEREFORE, THERE IS AN OVERALL LOW CONFIDENCE IN THE
JTWC TRACK FORECAST.//
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