Tropical Storm ONE Advisory Cts, 05.01.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 01W (ONE)
WARNING NR 001//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION (TD) 01W (ONE), LOCATED APPROXIMATELY 217 NM
SOUTHEAST OF MAJURO, MARSHALL ISLANDS, HAS TRACKED NORTHWESTWARD AT
13 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR)
SATELLITE IMAGERY SHOWS PERSISTENT CONVECTION OVER AN OBSCURED LOW
LEVEL CIRCULATION. A WEAK AND FRAGMENTED FORMATIVE BAND IS ALSO
EVIDENT ALONG THE SOUTHERN FLANK. THE INITIAL POSITION IS PLACED WITH
FAIR CONFIDENCE BASED ON THE EIR LOOP AND LINED UP WITH A SEMI-CLOSED
CIRCULATION FEATURE IN THE 041503Z 36GHZ SSMIS MICROWAVE IMAGE. THE
INITIAL INTENSITY OF 25 KNOTS IS BASED ON THE DVORAK INTENSITY
ESTIMATES OF T1.0 AND T1.5 FROM KNES AND PGTW AND IS CONSISTENT WITH
THE EIR CONVECTIVE STRUCTURE. THE INITIAL POSITION AND INTENSITY ARE
ALSO CONSISTENT WITH NEARBY SURFACE OBSERVATIONS. ENVIRONMENTAL
ANALYSIS INDICATES A MARGINALLY FAVORABLE ENVIRONMENT WITH LOW TO
MODERATE (15 TO 20 KNOT) VERTICAL WIND SHEAR (VWS) OFFSET BY GOOD
RADIAL OUTFLOW WITH A STRONG POLEWARD BIAS. SEA SURFACE TEMPERATURES
ARE VERY CONDUCIVE AT 28-30 CELSIUS. THE CYCLONE IS TRACKING ALONG
THE SOUTHWEST PERIPHERY OF THE SUBTROPICAL RIDGE (STR) TO THE
NORTH-NORTHEAST.
3. FORECAST REASONING.
   A. THIS IS THE INITIAL PROGNOSTIC REASONING MESSAGE AND SETS THE
FORECAST PHILOSOPHY FOR THIS SYSTEM.
   B. TD 01W WILL CONTINUE TRACKING NORTHWESTWARD TOWARD A BREAK IN
THE STR. AFTER TAU 48 AND TRACKING OVER MAJURO, A SECONDARY STR TO
THE NORTHWEST WILL ASSUME STEERING AND DRIVE THE SYSTEM ON A MORE
WEST-NORTHWESTWARD DIRECTION AND, BY TAU 72, WILL JUST HAVE TRACKED
OVER KWAJALEIN ATOLL. DECREASING VWS AND IMPROVING POLEWARD OUTFLOW
WILL FUEL A SLOW INTENSIFICATION TO 45 KNOTS BY TAU 72.
   C. AFTER TAU 72, TD 01W WILL CONTINUE ON A WEST-NORTHWESTWARD
TRACK TOWARD GUAM UNDER THE SECONDARY STR. THE FAVORABLE
ENVIRONMENTAL CONDITIONS WILL PERSIST AND PROMOTE FURTHER
INTENSIFICATION, REACHING 55 KNOTS (POSSIBLY HIGHER) BY TAU 120. THE
AVAILABLE NUMERICAL GUIDANCE IS IN OVERALL GOOD AGREEMENT WITH THE
TRACK WITH CTCX AS THE NOTABLE OUTLIER ON THE LEFT MARGIN OF THE
MODEL ENVELOPE. HOWEVER, DUE TO THE FORMATIVE NATURE OF THE SYSTEM,
THERE IS LOW CONFIDENCE IN ALL PORTIONS OF THE FIRST JTWC WARNING
TRACK THAT IS LAID JUST RIGHT OF CONSENSUS TO OFFSET THE UNLIKELY
CTCX SOLUTION.//
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