WDPN32 PGTW 182100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 10W (TEN) WARNING NR
05//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM 10W (TEN), LOCATED APPROXIMATELY 222 NM NORTH-
NORTHWEST OF ANDERSEN AFB, GUAM, HAS TRACKED NORTH-NORTHEASTWARD
AT 09 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED
SATELLITE IMAGERY DEPICTS BUILDING CENTRAL CONVECTION OBSCURING THE
LOW LEVEL CIRCULATION CENTER (LLCC). A RECENT SCATTEROMETER PASS
SHOWED A WELL-DEFINED SYMMETRIC LLCC WITH THE STRONGEST WINDS FOUND
ALONG THE SOUTHERN SEMI-CIRCLE WHICH IS BEING ENHANCED BY THE STRONG
WESTERLY SURGE. AN 181702Z SSMI 85GHZ MICROWAVE IMAGE SHOWED WELL
DEFINED SHALLOW BANDING WRAPPING INTO THE LLCC WITH THE BULK OF
CONVECTION DISPLACED SLIGHTLY WEST OF CENTER. THE CURRENT POSITION
IS BASED ON THE MICROWAVE IMAGE WITH GOOD CONFIDENCE. THE SYSTEM HAS
BEEN INCREASED TO TROPICAL STORM INTENSITY BASED ON DVORAK INTENSITY
ESTIMATES OF T2.5 (35 KNOTS) FROM PGTW AND KNES. ENVIRONMENTAL
CONDITIONS ARE CONTINUING TO IMPROVE WITH THE UPPER LEVEL LOW
WEAKENING AND MOVING FURTHER AWAY FROM TS 10W. THEREFORE, PRESSURE
ON THE NORTHERN SIDE HAS REDUCED ALLOWING AN EXPANSION OF MOISTURE
DUE TO RADIAL OUTFLOW OVER THE SYSTEM. VERTICAL WIND SHEAR VALUES
ARE 10 TO 15 KNOTS AND SEA SURFACE TEMPERATURES ARE WARM NEAR 30
CELSIUS. TS 10W IS CURRENTLY TRACKING NORTH-NORTHEASTWARD WITHIN THE
LOW- TO MID-LEVEL SOUTHWESTERLY FLOW.
3. FORECAST REASONING.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
B. TS 10W WILL CONTINUE TO TRACK NORTHEASTWARD OVER THE NEXT 36
HOURS UNDER THE COMBINED EFFECTS OF THE STRONG SOUTHWESTERLY FLOW
AND A BUILDING LOW TO MID-LEVEL EXTENSION OF THE SUB-TROPICAL RIDGE
(STR) LOCATED TO THE NORTHEAST. DURING THIS TIME EXPECT CONTINUED
INTENSIFICATION DUE TO THE FAVORABLE ENVIRONMENTAL CONDITIONS;
HOWEVER, THE IMPACTS OF THE UPPER LEVEL LOW PREVIOUSLY MENTIONED
WILL CONTINUE TO HINDER SIGNIFICANT INTENSIFICATION. BEYOND TAU 48,
TS 10W WILL BEND TO THE NORTHWEST AS THE STR STRENGTHENS AND BUILDS
NORTH OF THE CYCLONE. TS 10W WILL MAINTAIN AN INTENSIFY 50 KNOTS AS
IT MOVES OVER A COOL POOL OF LESS THAN FAVORABLE WATERS.
C. IN THE EXTENDED FORECAST, THE SYSTEM WILL CONTINUE TO TRACK
ALONG THE SOUTHWESTERN TO WESTERN PERIPHERY OF THE STEERING STR.
SEA SURFACE TEMPERATURES WILL INCREASE ALONG THE EASTERN COAST OF
JAPAN AND THE SYSTEM SHOULD GAIN A POLEWARD OUTFLOW CHANNEL AS IT
TAPS INTO THE MID-LATITUDE WESTERLIES AHEAD OF AN APPROACHING
SHORTWAVE TROUGH. LAND INTERACTION NEAR TAU 120 WILL PREVENT
CONTINUED INTENSIFICATION AS IT TURNS POLEWARD. DYNAMIC MODEL
GUIDANCE CONTINUES TO SHOW MULTIPLE SCENARIOS DUE TO INTERACTION
WITH NUMEROUS TROPICAL DISTURBANCES ROTATING AROUND THE MONSOON
GYRE. GFS, HWRF AND COAMPS-TC (CTCX) DEPICT THE SYSTEM SLOWING AND
TURNING EAST NEAR TAU 36 IN RESPONSE TO A DEVELOPING TROPICAL
DISTURBANCE. ECMWF DEPICTS THE SYSTEM TRACKING NORTHWESTWARD
IMMEDIATELY, INTO RIDGING, AND THEN REJOINING THE REMAINING GUIDANCE
NEAR TAU 72. THIS SOLUTION IS NOT FEASIBLE AT THIS TIME DUE TO THE
RIDGE POSITIONED NORTH OF THE SYSTEM. THE REMAINING GUIDANCE
(NAVGEM, COTC, EGRR, GFDN, AEMN) IS IN AGREEMENT ON THE CURRENT
TRACK FORECAST AND, BASED ON THE CURRENT STEERING PATTERN, IS THE
MOST REALISTIC SOLUTION. HOWEVER, GIVEN THE MULTIPLE SOLUTIONS AND
POTENTIAL INTERACTION WITH OTHER STORMS, THE FORECAST CONFIDENCE
REMAINS LOW.//
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