Tropical Storm NOUL Advisory Wed May 06

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 06W (NOUL) WARNING NR 15//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 06W (NOUL), LOCATED APPROXIMATELY 933 NM EAST-
SOUTHEAST OF MANILA, PHILIPPINES HAS TRACKED WEST-NORTHWESTWARD AT
08 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED
SATELLITE IMAGERY DEPICTS SPIRAL BANDING WRAPPING INTO A DEEP
CENTRAL DENSE OVERCAST FEATURE OBSCURING THE LOW LEVEL CIRCULATION
CENTER. A 061035Z SSMIS 91GHZ MICROWAVE IMAGE SHOWS A DEEP
CONVECTIVE CENTRAL CORE STRUCTURE WITH AN OPEN MICROWAVE EYE FEATURE
AND BROKEN CONVECTIVE SPIRAL BANDING. THE INITIAL POSITION IS BASED
ON THE AFOREMENTIONED MICROWAVE IMAGE AND A 061241Z SCATTEROMETER
PASS WITH GOOD CONFIDENCE. THE INITIAL INTENSITY IS BASED ON AN
OVERALL ASSESSMENT OF DVORAK INTENSITY ESTIMATES FROM ALL AGENCIES.
UPPER LEVEL ANALYSIS INDICATES A FAVORABLE ENVIRONMENT WITH NEAR
RADIAL OUTFLOW AND LOW TO MODERATE (10-15 KNOT) VERTICAL WIND SHEAR
THAT IS IN PHASE WITH THE CURRENT MOVEMENT. TY NOUL IS MOVING WEST-
NORTHWESTWARD UNDER THE INFLUENCE OF A SUB-TROPICAL RIDGE (STR) TO
THE NORTHWEST.
3. FORECAST REASONING.
   A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM
THE PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TY NOUL WILL CONTINUE TO TRACK WEST-NORTHWESTWARD AS THE STR
TO THE NORTHWEST REMAINS THE DOMINANT STEERING MECHANISM.
ENVIRONMENTAL CONDITIONS WILL REMAIN MOSTLY FAVORABLE WITH LOW TO
MODERATE VERTICAL WIND SHEAR AND GOOD DIVERGENT OUTFLOW LEADING TO
GRADUAL INTENSIFICATION. BEYOND TAU 48, AN UPPER LEVEL RIDGE PASSING
TO THE NORTH WILL BUILD THE STEERING STR, KEEPING THE SYSTEM ON A
WEST-NORTHWESTWARD TRAJECTORY AS IT APPROACHES THE CENTRAL
PHILIPPINES. NEAR TAU 72, AN UPPER LEVEL TROUGH IS FORECAST TO PASS
TO THE NORTH CAUSING THE STR TO WEAKEN, ALLOWING TY 06W TO TURN
POLEWARD AND ROUND THE SOUTHWESTERN PERIPHERY OF THE STEERING STR.
ADDITIONALLY, 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, THE SYSTEM WILL CONTINUE TO TURN POLEWARD AND
START TO WEAKEN DUE TO LAND INTERACTION AS IT SKIRTS THE EASTERN
COAST OF THE CENTRAL PHILIPPINES AND LUZON. DYNAMIC MODEL GUIDANCE
HAS SHIFTED WESTWARD AGAIN DUE TO UNCERTAINTY IN THE MID-LATITUDE
PATTERN IMPACTING THE STEERING STR. BASED ON THE RECENT INSTABILITY
IN THE EXTENDED PORTION OF THE MULTI-MODEL CONSENSUS, THERE IS LOW
CONFIDENCE IN THE JTWC TRACK FORECAST.//
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