MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 16W (BOLAVEN) WARNING NR 16//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TYPHOON 16W (BOLAVEN), LOCATED APPROXIMATELY 470 NM SOUTHEAST OF
KADENA AB, OKINAWA, JAPAN, HAS TRACKED WESTWARD AT 05 KNOTS OVER THE
PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY SHOWS
COOLING CLOUD TOPS OVER THE EASTERN PORTION OF THE LOW-LEVEL
CIRCULATION CENTER (LLCC) WITH MULTIPLE VIGOROUS FEEDER BANDS
FURTHER SOUTH AND WEST. A NOTICEABLE LACK OF DEEP CONVECTION IS SEEN
OVER THE NORTHWESTERN QUADRANT OF THE LLCC AND MATCHES WELL WITH THE
MODERATE 20-KNOT VERTICAL WIND SHEAR (VWS) ANALYZED OVER THIS
SECTOR. THE CURRENT POSITION IS BASED ON AN EXTRAPOLATION FROM THE
231617Z TRMM 37 GHZ MICROWAVE IMAGE WITH FAIR CONFIDENCE. THE
CURRENT INTENSITY IS BASED ON THE HIGHER SIDE OF DVORAK ESTIMATES
RANGING FROM 77 TO 102 KNOTS FROM KNES, RJTD, AND PGTW. UPPER-LEVEL
ANALYSIS INDICATES TY 16W IS LOCATED APPROXIMATELY TEN DEGREES
EQUATORWARD OF THE NORTHEAST-SOUTHWEST ORIENTATED SUBTROPICAL RIDGE
(STR) AXIS. THE SELF-MAINTAINED MESO-ANTICYCLONE REMAINS OVERHEAD OF
THE LLCC PROVIDING RADIAL OUTFLOW AND WEAK (05-10 KNOTS) VWS ABOVE
THE SYSTEM. UPPER-LEVEL TROUGHING EXISTS JUST NORTH OF TY 16W AND
CAN ACCOUNT FOR THE LACK OF DEEP CONVECTION MENTIONED EARLIER. TY
16W CONTINUES TO TRACK ALONG THE SOUTHWESTERN PERIPHERY OF THE DEEP
LAYERED STR TO THE NORTH, ANCHORED JUST EAST OF HONSHU, JAPAN.
3. FORECAST REASONING.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
B. TY 16W WILL CONTINUE TO TRACK ALONG THE SOUTHWESTERN PERIMETER
OF THE STR THROUGH TAU 72; HOWEVER, GIVEN THE EXTRAORDINARY SIZE AND
MAGNITUDE OF THE CYCLONE, IT WILL MODIFY THE STR, RESULTING IN A
MORE POLEWARD STORM MOTION. AFTER TAU 48 A MID-LATITUDE TROUGH
APPROACHING FROM MONGOLIA AND TRACKING TOWARD THE YELLOW SEA WILL
WEAKEN THE STR RESULTING IN AN EVEN MORE POLEWARD STORM MOTION. THE
SYSTEM WILL STEADILY INTENSIFY, PEAKING AT 120 KNOTS BY TAU 36. THE
SYSTEM WILL THEN MAINTAIN INTENSITY AS IT APPROACHES LANDFALL OVER
OKINAWA NEAR 260500Z. BY TAU 72 TY 16W SHOULD BEGIN TO SLOWLY WEAKEN
DUE TO DECREASING OCEAN HEAT CONTENT. HOWEVER, A BRIEF PERIOD OF
ENHANCED POLEWARD OUTFLOW OUT AHEAD OF THE APPROACHING TROUGH SHOULD
COMBAT THE DECLINING OCEAN PARAMETERS. OBJECTIVE AID GUIDANCE IS IN
TIGHT AGREEMENT WITH THE MODEL CONSENSUS, AND ECMWF, DIRECTLY OVER
OKINAWA; THEREFORE, THERE IS HIGH CONFIDENCE IN THIS PORTION OF THE
TRACK FORECAST.
C. AFTER TAU 72, TY 16W SHOULD TRACK NORTHWARD INTO THE WEAKNESS
CAUSED BY THE PREVIOUSLY MENTIONED TROUGH. TRACK SPEEDS WILL
ACCELERATE DURING THIS TIME AND INTENSITY WILL BE ON THE DECLINE AS
OCEAN PARAMETERS BECOME LESS FAVORABLE AND WESTERLY VWS INCREASES TO
STRONG LEVELS. EXTRA-TROPICAL TRANSITION IS EXPECTED TO BEGIN
OVERLAND BY TAU 120. OBJECTIVE AID GUIDANCE IS IN FAIR AGREEMENT IN
REGARDS TO THE LANDFALL POSITION WITH APPROXIMATELY 135 NM SPREAD
BETWEEN THE LEFTMOST OUTLIER, GFS, AND THE RIGHTMOST OUTLIERS,
NOGAPS/ECMWF. DUE TO THE DEEP UPPER-LEVEL TROUGHING AND AMPLIFIED
RIDGING IN RESPONSE THERE IS HIGH CONFIDENCE IN THIS PORTION OF THE
TRACK FORECAST CURVING OVER NORTHERN KOREA. THIS IS FURTHER
VALIDATED BY ANALYSIS OF THE LATEST GFS AND ECMWF ENSEMBLE RUNS.//
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