[Tropical] Tropical Cyclone Discussion

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WTNT45 KNHC 171447
TCDAT5
HURRICANE EMILY DISCUSSION NUMBER  27
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 AM EDT SUN JUL 17 2005

SATELLITE IMAGERY AND REPORTS FROM AN AIR FORCE RESERVE HURRICANE
HUNTER AIRCRAFT INDICATE THAT EMILY HAS WEAKENED SLIGHTLY OVER THE
PAST 12 HR.  THE EYE HAS BECOME LESS DISTINCT IN SATELLITE IMAGERY
AND THE OVERALL CLOUD PATTERN HAS BECOME A LITTLE RAGGED.  THE
AIRCRAFT INDICATES THE CENTRAL PRESSURE HAS RISEN TO 946 MB...WITH
MAXIMUM 700 MB FLIGHT-LEVEL WINDS OF 142 KT IN THE NORTHEASTERN
QUADRANT.  THE INITIAL INTENSITY WILL BE 130 KT.

THE INITIAL MOTION REMAINS 290/17.  THERE IS LITTLE CHANGE TO EITHER
THE FORECAST PHILOSOPHY OR FORECAST TRACK.  EMILY REMAINS ON THE
SOUTH SIDE OF AN EAST-WEST LOW/MID LEVEL RIDGE EXTENDING FROM THE
ATLANTIC ACROSS THE NORTHERN GULF COAST TO TEXAS.  LARGE-SCALE
MODELS FORECAST THE RIDGE TO GENERALLY PERSIST...WITH A WEAKNESS
PERHAPS DEVELOPING IN 36-48 HR OVER THE WESTERN GULF COAST AS A
MID-LATITUDE SHORTWAVE TROUGH PASSES TO THE NORTH.  TRACK MODEL
GUIDANCE IS IN GOOD AGREEMENT ON A GENERAL WEST-NORTHWEST MOTION
FOR 36-48 HR...FOLLOWED BY A GRADUAL TURN TOWARD THE WEST AS THE
WEAKNESS IN THE RIDGE FILLS.  WHETHER THE WEAKNESS WILL BE STRONG
ENOUGH TO ALLOW A MORE NORTHWARD TRACK THAN CURRENTLY FORECAST IS
QUESTIONABLE.  HOWEVER...THE TRACK AFTER 36 HR IS ALONG THE
NORTHERN SIDE OF THE GUIDANCE ENVELOPE.

IT IS UNCLEAR WHETHER THE WEAKENING THAT HAS OCCURRED IS DUE TO AN
INTERNAL CYCLE OR EXTERNAL FORCING.  A RECENT SSM/I OVERPASS DOES
NOT SHOW CONCENTRIC EYEWALLS...AND WHILE CIRRUS OUTFLOW HAS
DIMINISHED OVER THE SOUTHERN SEMICIRCLE THERE ARE NO OBVIOUS SIGNS
OF SHEAR AT THIS TIME.  EMILY CONTINUES TO GENERATE COLD CONVECTIVE
TOPS...SO THERE IS STILL POTENTIAL FOR RE-INTENSIFICATION OR
FLUCTUATIONS BEFORE LANDFALL IN YUCATAN.  EMILY SHOULD WEAKEN OVER
YUCATAN... THEN RE-INTENSIFY INTO A MAJOR HURRICANE OVER THE
WESTERN GULF OF MEXICO.  THE CYCLONE SHOULD THEN WEAKEN QUICKLY
AFTER LANDFALL IN NORTHEASTERN MEXICO AND DISSIPATE BY 120 HR OVER
THE MOUNTAINS OF NORTHERN MEXICO.

FORECASTER BEVEN


FORECAST POSITIONS AND MAX WINDS

INITIAL      17/1500Z 18.6N  83.6W   130 KT
 12HR VT     18/0000Z 19.5N  85.9W   130 KT
 24HR VT     18/1200Z 20.9N  88.9W   110 KT...INLAND
 36HR VT     19/0000Z 22.2N  91.6W    85 KT...OVER WATER
 48HR VT     19/1200Z 23.1N  94.2W   100 KT
 72HR VT     20/1200Z 24.5N  99.0W    75 KT...INLAND
 96HR VT     21/1200Z 24.5N 104.0W    20 KT...INLAND DISSIPATING
120HR VT     22/1200Z...DISSIPATED


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