WTPZ45 KNHC 260252 RRA

TCDEP5



HURRICANE SEYMOUR DISCUSSION NUMBER  12

NWS NATIONAL HURRICANE CENTER MIAMI FL       EP202016

800 PM PDT TUE OCT 25 2016



SEYMOUR HAS CONTINUED TO RAPIDLY INTENSIFY SINCE THE LAST ADVISORY.

THE EYE IS ABOUT 10-15 NMI WIDE IN INFRARED SATELLITE IMAGERY, BUT

IS LESS THAN 10 NMI WIDE IN A RECENT 0005Z SSMI/S MICROWAVE IMAGE,

INDICATING THAT THE EYE DIAMETER HAS CONTRACTED SINCE THE PREVIOUS

ADVISORY. THE INITIAL INTENSITY IS INCREASED TO 130 KT FOR THIS

ADVISORY BASED ON SATELLITE INTENSITY ESTIMATES OF T6.5/127 KT FROM

BOTH TAFB AND SAB, AND A T6.7/132 KT FROM UW-CIMSS ADT.



THE INITIAL MOTION IS NOW 285/13 KT. THE GLOBAL AND REGIONAL MODELS

REMAIN IN EXCELLENT AGREEMENT ON SEYMOUR MOVING STEADILY

WEST-NORTHWESTWARD AROUND THE SOUTHWESTERN PERIPHERY OF A DEEP-LAYER

RIDGE FOR THE NEXT 24 HOURS, FOLLOWED BY A TURN TOWARD THE NORTHWEST

IN 36 HOURS AS A STRONG SHORTWAVE TROUGH SIGNIFICANTLY ERODES THE

WESTERN PORTION OF THE RIDGE. BY 48 HOURS, SEYMOUR IS EXPECTED TO

SLOW DOWN APPRECIABLY AND TURN NORTH-NORTHWESTWARD AS THE CYCLONE

RAPIDLY WEAKENS AND BECOMES MORE VERTICALLY SHALLOW. AFTER THAT

TIME, THE SHALLOW POST-TROPICAL LOW IS FORECAST TO TURN BACK TOWARD

THE WEST-NORTHWEST UNDER THE INFLUENCE OF THE LOW-LEVEL TRADE WIND

FLOW. THE OFFICIAL FORECAST TRACK IS SIMILAR TO THE PREVIOUS

ADVISORY, AND LIES CLOSE TO BLEND OF THE TVCX AND HCCA CONSENSUS

MODELS.



SOME ADDITIONAL SLIGHT STRENGTHENING IS POSSIBLE DURING THE NEXT

6-12 HOURS DUE TO THE SMALL EYE, LOW SHEAR CONDITIONS, AND WARM

SSTS. AFTER THAT TIME, INCREASING SOUTHWESTERLY VERTICAL WIND SHEAR,

COOLER WATERS, INCLUDING SIGNIFICANT COLD UPWELLING BY 24 HOURS AND=