Tropical Storm MAN-YI Advisory Wed Nov 21

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 34W (MAN-YI) WARNING NR
07//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM 34W (MAN-YI), LOCATED APPROXIMATELY 31 NM NORTH-
NORTHWEST OF PULUWAT, HAS TRACKED WEST-NORTHWESTWARD AT 20 KNOTS
OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY
(MSI) REVEALS DEEP CENTRAL CONVECTION, RADIAL OUTFLOW, AND EXTENSIVE
RAIN BANDS, PARTICULARLY IN THE NORTHEAST QUADRANT. THE INITIAL
POSITION IS PLACED WITH GOOD CONFIDENCE BASED ON A 210626Z GMI 36
GHZ MICROWAVE IMAGE WHICH SHOWED DEEP CONVECTION TO THE NORTHWEST OF
THE LOW LEVEL CIRCULATION CENTER (LLCC) WITH BANDING FEATURES
EVIDENT IN ALL QUADRANTS EXCEPT THE SOUTHEASTERN ONE. THE INITIAL
INTENSITY OF 55 KNOTS IS HEDGED ABOVE THE PGTW DVORAK CURRENT
INTENSITY ESTIMATE OF T3.0 (45 KNOTS) FROM PGTW AND KNES BECAUSE OF
A 202152Z CIMSS SATCON ESTIMATE OF 59 KNOTS. LOW (10-15 KNOT)
VERTICAL WIND SHEAR (VWS), RADIAL OUTFLOW, AND WARM (29-30 CELSIUS)
SEA SURFACE TEMPERATURE (SST) MAKE THE SURROUNDING ENVIRONMENT
FAVORABLE. TS 34W IS TRACKING ALONG THE SOUTHERN PERIPHERY OF A
SUBTROPICAL RIDGE (STR).
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE. IN THE EXTENDED PERIOD, THE
TRACK HAS SHIFTED WESTWARD TO REFLECT THE COLLECTIVE CHANGE IN THE
NUMERICAL MODEL GUIDANCE.
   B. THROUGH TAU 48, THE STR WILL CONTINUE STEERING TS 34W WEST-
NORTHWESTWARD. BY TAU 72, AN APPROACHING MID-LATITUDE TROUGH WILL
CREATE A WEAKNESS IN THE STR AND TEMPORARILY TURN THE TRACK
NORTHWARD. THOUGH TAU 36, FAVORABLE ENVIRONMENTAL CONDITIONS WILL
ALLOW THE SYSTEM TO STEADILY INTENSIFY TO 95 KNOTS. AFTER TAU 36,
HIGH VWS WILL BEGIN A WEAKENING TREND. MODEL GUIDANCE IS IN
EXCELLENT AGREEMENT THROUGH TAU 72, LENDING HIGH CONFIDENCE TO THIS
PORTION OF THE JTWC FORECAST TRACK.
   C. BEYOND TAU 72, TS 34W WILL BECOME QUASI-STATIONARY AND TURN
WESTWARD AS THE STR BUILDS BACK IN BEHIND THE MID-LATITUDE TROUGH.
HIGH VWS AND UPPER LEVEL CONVERGENCE, ACCOMPANIED BY DRY AIR
ENTRAINMENT, ARE EXPECTED TO CONTINUE WEAKENING THE CYCLONE THROUGH
THE REMAINDER OF THE FORECAST PERIOD. EVERY MEMBER OF THE CONSENSUS
PREDICTS THE WESTWARD TURN AT THE END OF THE PERIOD, ALTHOUGH THE
TRACKS SHOW SOME VARIABILITY. THE JTWC TRACK FORECAST HAS BEEN
ADJUSTED TO CAPTURE THIS SLOW WESTWARD TURN. BASED ON THE EVOLVING
SYNOPTIC ENVIRONMENT IN THE EXTENDED PERIOD, CONFIDENCE IS LOW IN
THE EXTENDED PORTION OF THE JTWC TRACK FORECAST.//
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