Tropical Storm NOUL Advisory Sun May 03

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 06W WARNING NR 1//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION 06W (SIX), LOCATED APPROXIMATELY 205 NM EAST-
SOUTHEAST OF YAP, HAS TRACKED WESTWARD AT 07 KNOTS OVER THE PAST
SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS THE
SYSTEM HAS CONSOLIDATED AS CONVECTIVE BANDS, ALBEIT FRAGMENTED AND
SHALLOW, WRAPPED TIGHTER INTO A BROAD AND ILL-DEFINED LOW LEVEL
CIRCULATION CENTER. THE INITIAL POSITION IS BASED ON THE MSI LOOP
AND EXTRAPOLATED FROM A LOW REFLECTIVITY NOTCH FEATURE ON A 022222Z
SSMIS MICROWAVE PASS WITH FAIR CONFIDENCE. THE INITIAL INTENSITY OF
25 KNOTS IS BASED ON AN OVERALL ASSESSMENT OF DVORAK ESTIMATES FROM
PGTW, KNES, AND RJTD. UPPER LEVEL ANALYSIS INDICATES TD 06W IS JUST
SOUTH OF THE RIDGE AXIS IN AN AREA OF MODERATE (15-20 KNOT) EASTERLY
VERTICAL WIND SHEAR (VWS). HOWEVER, THE VWS IS SUBSTANTIALLY OFFSET
BY GOOD RADIAL OUTFLOW, WITH A STRONG POLEWARD BIAS. THE CYCLONE IS
CURRENTLY TRACKING ALONG THE SOUTHERN PERIPHERY OF AN EXTENSION OF
THE SUBTROPICAL RIDGE (STR) TO THE NORTHEAST.
3. FORECAST REASONING.
   A. THIS IS THE INITIAL PROGNOSTIC REASONING BULLETIN AND SETS THE
FORECAST PHILOSOPHY FOR THIS SYSTEM.
   B. TD 06W IS EXPECTED TO SLOW DOWN OVER THE NEXT 36 HOURS AS IT
APPROACHES A BREAK BETWEEN THE AFOREMENTIONED STR LEAF AND A NEW STR
LEAF TO THE NORTHWEST. AFTERWARDS, THE NEW STR LEAF WILL ASSUME
STEERING AND DRIVE THE CYCLONE ON A WEST-NORTHWESTWARD (WNW)
TRAJECTORY TOWARDS LUZON, PHILIPPINES. THE VWS IS EXPECTED TO WEAKEN
AND OUTFLOW TO REMAIN ROBUST. THESE, PLUS THE PERENNIAL WARM WATERS
OF THE PHILIPPINE SEA WILL FUEL STEADY INTENSIFICATION.
   C. IN THE EXTENDED TAUS, TD 06W WILL CONTINUE TO INTENSIFY AND
REMAIN ON A WNW TRACK UNDER THE STEERING INFLUENCE OF THE NEW STR
LEAF. BY END OF FORECAST, THE SYSTEM WILL BE AT TYPHOON INTENSITY OF
8O KNOTS, POSSIBLY STRONGER. THE INITIAL SET OF NUMERIC GUIDANCE IN
LOOSE AGREEMENT AND GIVEN THE UNCERTAIN STORM MOTION AS THE CYCLONE
APPROACHES A WEAK STEERING ENVIRONMENT, THERE IS LOW CONFIDENCE IN
THE FIRST JTWC FORECAST TRACK ON THIS SYSTEM.//
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