Tropical Storm CHAN-HOM Advisory jue, 02-07

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 09W (CHAN-HOM) WARNING
NR 07//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 09W (CHAN-HOM), LOCATED APPROXIMATELY 470 NM
EAST-SOUTHEAST OF ANDERSEN AFB, GUAM, HAS TRACKED WESTWARD AT 16
KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY DEPICTS A DEEPENING CENTRAL DENSE OVERCAST FEATURE OBSCURING
THE LOW LEVEL CIRCULATION CENTER (LLCC) WITH THE REMNANTS OF
TROPICAL DISTURBANCE 94W BEGINNING TO WRAP INTO THE SOUTHERN
PERIPHERY. A 012146Z SSMIS MICROWAVE IMAGE SHOWS A PARTIALLY EXPOSED
LLCC JUST EAST OF THE MOST INTENSE CONVECTION. THE CURRENT POSITION
IS BASED ON THE LLCC IN THE AFOREMENTIONED MICROWAVE IMAGE WITH GOOD
CONFIDENCE. THE INTENSITY HAS BEEN INCREASED TO 55 KNOTS BASED ON
CONCURRING DVORAK INTENSITY ESTIMATES OF T3.5 FROM RJTD AND PGTW.
UPPER LEVEL ANALYSIS INDICATES THAT THE SYSTEM IS LOCATED IN A
MARGINALLY FAVORABLE ENVIRONMENT WITH LOW TO MODERATE (10 TO 20
KNOT) VERTICAL WIND SHEAR (VWS) AND EXCELLENT DIFFLUENT OUTFLOW
ALOFT. TS 09W IS CURRENTLY TRACKING ALONG THE SOUTHERN PERIPHERY OF
A SUB-TROPICAL RIDGE (STR) TO THE NORTH.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
   B. TS 09W WILL MAINTAIN A WESTWARD TRAJECTORY THROUGH TAU 36
UNDER THE INFLUENCE OF THE STEERING STR. THE SYSTEM WILL GRADUALLY
INTENSIFY DURING THIS TIME AS IT ABSORBS THE REMNANTS OF TROPICAL
DISTURBANCE 94W AND ENCOUNTERS MODERATE (20-25 KNOT) VWS. BEYOND TAU
36, TS 09W WILL BEGIN TO TURN TO THE NORTHWEST TOWARDS A BREAK IN
THE STEERING STR, DUE TO A PASSING MID-LATITUDE TROUGH TO THE NORTH.
AFTER TAU 48, AS THE SYSTEM GAINS LATITUDE, VWS WILL DECREASE AND
OUTFLOW WILL IMPROVE, INCREASING THE INTENSIFICATION RATE.
   C. TS 09W WILL CONTINUE TO ACCELERATE NORTHWESTWARD AND INTENSIFY
BASED ON FAVORABLE ENVIRONMENTAL CONDITIONS. AFTER TAU 96, THE STR
WILL BUILD BACK IN NORTH OF THE SYSTEM AS MID-LATITUDE RIDGE PASSES
TO THE NORTH. MODEL GUIDANCE CONTINUES TO BE IN EXCELLENT AGREEMENT
THROUGH TAU 36; HOWEVER, THERE IS A SIGNIFICANT SPREAD OF 190NM AS
THE SYSTEM PASSES THE MARIANA ISLANDS. DUE TO OVERALL UNCERTAINTY IN
MODEL GUIDANCE, THERE IS LOW CONFIDENCE IN THE JTWC FORECAST.//
NNNN
NNNN