000
WTNT43 KNHC 152032
TCDAT3
TROPICAL STORM KARL DISCUSSION NUMBER   5
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL132010
400 PM CDT WED SEP 15 2010

KARL IS SLOWLY WEAKENING AS THE CENTER CROSSES THE YUCATAN
PENINSULA.  SATELLITE IMAGERY AND DATA FROM THE BELIZE CITY RADAR
INDICATE THE CYCLONE CONTINUES TO PRODUCE STRONG CONVECTION...BUT
THIS IS CURRENTLY CONFINED TO THE SOUTHWESTERN QUADRANT.  THERE ARE
NO OBSERVATION AVAILABLE NEAR THE CORE...AND THUS THE INITIAL
INTENSITY OF 40 KT IS SOMEWHAT UNCERTAIN.

THE INITIAL MOTION IS NOW 285/13.  THE CYCLONE REMAINS ON THE SOUTH
SIDE OF A LOW/MID-LEVEL RIDGE CENTERED OVER THE NORTHERN GULF
COAST...AND THIS FEATURE SHOULD STEER THE CYCLONE GENERALLY
WEST-NORTHWESTWARD OR WESTWARD ACROSS THE SOUTHWESTERN GULF OF
MEXICO INTO MAINLAND MEXICO.  THERE REMAINS SOME SPREAD IN THE
GUIDANCE...WITH THE HWRF INDICATING A MORE NORTHWARD MOTION ON THE
RIGHT SIDE OF THE GUIDANCE ENVELOPE AND THE GFDN A MORE WESTWARD
MOTION ON THE LEFT.  SEVERAL OF THE OTHER DYNAMICAL MODELS NOW
FORECAST KARL TO SLOW ITS FORWARD MOTION BEFORE REACHING THE COAST
OF MAINLAND MEXICO...AND ALSO FORECAST A TURN TO SOUTH OF WEST
MOTION NEAR OR JUST AFTER LANDFALL.  THE NEW FORECAST TRACK
REFLECTS BOTH OF THESE POSSIBILITIES...WITH THE NEW TRACK BEING
SIMILAR TO...BUT A LITTLE SLOWER THAN...THE PREVIOUS TRACK AFTER
36 HR.
 
KARL IS FORECAST TO WEAKEN TO A TROPICAL DEPRESSION BY THE TIME IT
REACHES THE WEST COAST OF THE YUCATAN PENINSULA IN ABOUT 12 HR. 
ONCE THE CENTER REACHES WATER...THE COMBINATION OF WARM SEA SURFACE
TEMPERATURES AND LIGHT VERTICAL WIND SHEAR SHOULD ALLOW
RE-INTENSIFICATION AS FORECAST BY ALL GUIDANCE.  IT SHOULD BE NOTED
THAT THE HWRF...WHILE FORECASTING STRENGTHENING...HAS CONSISTENTLY
KEPT KARL AT LESS THAN HURRICANE STRENGTH.  GIVEN THE SEEMINGLY
FAVORABLE ENVIRONMENT...THE INTENSITY FORECAST CALLS FOR KARL TO
REACH HURRICANE STRENGTH OVER THE GULF OF MEXICO IN AGREEMENT WITH
THE SHIPS AND LGEM MODELS.  THE FORECAST SHOWS A PEAK INTENSITY OF
70 KT...BUT KARL COULD BECOME STRONGER THAN THAT BETWEEN THE 48 AND
72 HR FORECAST POINTS.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      15/2100Z 19.0N  89.4W    40 KT...INLAND
 12HR VT     16/0600Z 19.6N  90.9W    30 KT...OVER WATER
 24HR VT     16/1800Z 20.5N  92.7W    35 KT
 36HR VT     17/0600Z 21.1N  94.4W    50 KT
 48HR VT     17/1800Z 21.3N  95.7W    65 KT
 72HR VT     18/1800Z 21.5N  98.5W    70 KT...INLAND
 96HR VT     19/1800Z 21.0N 101.5W    25 KT...INLAND
120HR VT     20/1800Z...DISSIPATED
 
$$
FORECASTER BEVEN