Tropical Storm NOUL Advisory Thu May 07

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 06W (NOUL) WARNING NR 14//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 06W (NOUL), LOCATED APPROXIMATELY 71 NM WEST OF YAP,
HAS TRACKED WESTWARD AT 07 KNOTS OVER THE PAST SIX HOURS.
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A MORE
SYMMETRIC AREA OF DEEP CENTRAL CONVECTION WITH SPIRAL BANDING
WRAPPING INTO AN OBSCURED LOW LEVEL CIRCULATION CENTER. A 060156Z
GMI MICROWAVE IMAGE SHOWS BROKEN CURVED CONVECTIVE BANDING ALONG THE
WESTERN QUADRANT WRAPPING INTO A COMPACT MICROWAVE EYE FEATURE. THE
INITIAL POSITION IS EXTRAPOLATED FROM THE MICROWAVE EYE AND
SUPPORTED BY A PGTW SATELLITE POSITION FIX. THE CURRENT INTENSITY
HAS BEEN INCREASED TO 75 KNOTS BASED ON THE IMPROVED CENTRAL CORE
STRUCTURE AND DVORAK INTENSITY ESTIMATES OF T4.5 (77 KNOTS) FROM
KNES AND PGTW. UPPER LEVEL ANALYSIS INDICATES AN IMPROVING
ENVIRONMENT WITH NEAR RADIAL OUTFLOW THAT IS EVIDENT ON THE WATER
VAPOR LOOP AND LOW TO MODERATE (10-15 KNOT) VERTICAL WIND SHEAR THAT
IS IN PHASE WITH CURRENT MOVEMENT; REDUCING IMPACTS. TY NOUL HAS
INCREASED FORWARD MOTION INDICATING THAT THE SUB-TROPICAL RIDGE
(STR) TO THE NORTHWEST HAS ASSUMED STEERING.
3. FORECAST REASONING.
   A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM
THE PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TYPHOON NOUL WILL CONTINUE TO TRACK WESTWARD TO WEST-
NORTHWESTWARD AS THE STR TO THE NORTHWEST REMAINS THE DOMINANT
STEERING MECHANISM. ENVIRONMENTAL CONDITIONS WILL REMAIN FAVORABLE
WITH LOW TO MODERATE VERTICAL WIND SHEAR AND GOOD DIVERGENT OUTFLOW.
BEYOND TAU 48, TY 06W WILL MOVE DOWNSTREAM FROM THE STR AXIS AND
GAIN AN ENHANCED POLEWARD OUTFLOW, FURTHER ASSISTING IN THE GRADUAL
INTENSIFICATION AND LEADING TO A MAXIMUM INTENSITY OF 125 KNOTS AT
TAU 72.
   C. AFTER TAU 72, AN UPPER-LEVEL TROUGH IS FORECAST TO PASS TO THE
NORTH CAUSING A BREAK IN THE STR, ALLOWING TY 06W TO TURN POLEWARD
AND ROUND THE SOUTHWESTERN PERIPHERY OF THE STEERING STR.
CONCURRENTLY, THE SYSTEM IS FORECAST TO SLIGHTLY WEAKEN THROUGH THE
END OF THE FORECAST PERIOD DUE TO LAND INTERACTION AS IT SKIRTS THE
EASTERN COAST OF THE CENTRAL PHILIPPINES AND LUZON. AVAILABLE MODEL
GUIDANCE HAS SHIFTED SLIGHTLY WESTWARD; HOWEVER, IT REMAINS OVERALL
IN GOOD AGREEMENT, LEADING TO HIGH CONFIDENCE IN THE JTWC TRACK
FORECAST.//
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