WDPN32 PGTW 180300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 10W (TEN) WARNING
NR 02//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL DEPRESSION (TD) 10W (TEN), LOCATED APPROXIMATELY 189 NM
WEST-NORTHWEST OF ANDERSEN AFB, GUAM, HAS TRACKED EASTWARD AT 08
KNOTS OVER THE PAST SIX HOURS. MAXIMUM SIGNIFICANT WAVE HEIGHT AT
180000Z IS 10 FEET. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI)
DEPICTS PERSISTENT SYMMETRIC CONVECTION ASSOCIATED WITH A DEFINED
AND PARTIALLY EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC) THAT IS
EMBEDDED WITHIN THE SOUTHWEST MONSOON SURGE. THE CURRENT POSITION IS
PLACED WITH FAIR CONFIDENCE BASED ON THE PARTIALLY EXPOSED LLCC IN
THE MSI LOOP. THE CURRENT INTENSITY IS BASED ON DVORAK INTENSITY
ESTIMATES OF T2.0 (30 KNOTS) FROM PGTW AND KNES. UPPER LEVEL
ANALYSIS INDICATES A MOSTLY FAVORABLE ENVIRONMENT WITH 10 TO 20 KNOT
EASTERLY VWS BEING OFFSET BY STRONG DIVERGENT OUTFLOW WITH
INDICATION OF A POINT SOURCE DEVELOPING OVER THE SYSTEM. HOWEVER,
THERE IS HIGH SHEAR AND SUBSIDENCE TO THE NORTHEAST OF THE LLCC DUE
TO AN UPPER LEVEL LOW LOCATED NEAR 29.0N 151.9E WHICH COULD HINDER
DEVELOPMENT. TD 10W IS TRACKING EAST-NORTHEASTWARD WITHIN THE LOW TO
MID-LEVEL SOUTHWESTERLY FLOW.
3. FORECAST REASONING.
A. DECREASED THE FORWARD SPEED OF THE SYSTEM IN THE EXTENDED
FORECAST DUE TO INCREASED GUIDANCE SHOWING THE POSSIBILITY OF DIRECT
CYCLONE INTERACTION WITH TROPICAL STORM 12W CREATING A COMPETING
STEERING ENVIRONMENT WITH THE STR TO THE NORTHEAST.
B. TD 10W WILL CONTINUE TO TRACK NORTHEASTWARD OVER THE NEXT 48
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 PREVENT SIGNIFICANT INTENSIFICATION. BEYOND TAU 48, TD 10W WILL
BEND TO THE NORTHWEST AS THE STR STRENGTHENS AND BUILDS NORTH OF THE
CYCLONE. TD 10W WILL CONTINUE TO INTENSIFY REACHING A PEAK INTENSITY
OF 55 KNOTS.
C. IN THE EXTENDED FORECAST, THE SYSTEM WILL CONTINUE TO TRACK
ALONG THE SOUTHERN TO SOUTHWESTERN PERIPHERY OF THE STEERING STR.
SEA SURFACE TEMPERATURES WILL BEGIN TO DECREASE; HOWEVER, THE
POLEWARD OUTFLOW CHANNEL SHOULD INCREASE AS THE SYSTEM TAPS INTO THE
MID-LATITUDE WESTERLIES AHEAD OF AN APPROACHING SHORTWAVE TROUGH. BY
TAU 120, TD 10W WILL MAKE LANDFALL IN NORTHERN HONSHU, JAPAN. LAND
INTERACTION WILL CAUSE THE SYSTEM TO WEAKEN AS IT TURNS POLEWARD AND
ROUNDS THE STR AXIS. HOWEVER, THERE IS THE POTENTIAL FOR THE SYSTEM
TO INTERACT WITH TROPICAL STORM 12W THAT WILL BE LOCATED TO THE
SOUTHWEST. AT THIS TIME THE SYSTEMS WILL BE MORE THAN 600NM APART
WHICH WILL CAUSE A SLOWER FORWARD SPEED DUE TO THE COMPETING
STEERING MECHANISMS. THERE IS AN ALTERNATE SCENARIO WHERE THE
CYCLONES COULD CLOSE WITHIN 400NM. IF THIS OCCURS THEN THE TRACK
WILL TURN TO THE SOUTHWEST AND TD 10W WILL WEAKEN. DYNAMIC MODEL
GUIDANCE IS IMPROVED; HOWEVER, GFS AND HWRF DO SHOW THE SECOND
SCENARIO OCCURRING. AEMN (GFS ENSEMBLE MEAN) SHOWS THE SYSTEM
SLOWING DOWN AND THEN TURNING POLEWARD WHICH INDICATES THAT THERE IS
LOW CONFIDENCE IN THE GFS DETERMINISTIC SOLUTION.//
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