000
WTNT43 KNHC 142052
TCDAT3
TROPICAL STORM KARL DISCUSSION NUMBER   1
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL132010
500 PM EDT TUE SEP 14 2010
 
AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT INVESTIGATING THE LOW
PRESSURE AREA IN THE NORTHWESTERN CARIBBEAN SEA FOUND A SMALL AND
VIGOROUS WIND/PRESSURE CENTER INSIDE THE LARGER CYCLONIC ENVELOPE.
THE MAXIMUM FLIGHT-LEVEL WINDS WERE 41 KT AT LESS THAN 1500 FT JUST
EAST OF THE CENTER...AND THE SFMR ESTIMATED RELIABLE-LOOKING WINDS
OF 35 KT OUTSIDE OF THE HEAVY RAIN AREAS.  THE MINIMUM CENTRAL
PRESSURE WAS 1001 MB.  BASED ON THESE DATA...THE SYSTEM IS UPGRADED
STRAIGHT TO TROPICAL STORM KARL WITH AN INITIAL INTENSITY OF 35 KT.
 
THE INITIAL MOTION IS 295/13.  KARL IS LOCATED ON THE SOUTH SIDE OF
A DEEP-LAYER RIDGE CENTERED ALONG THE NORTHERN GULF COAST.  THE
TRACK GUIDANCE IS IN GOOD AGREEMENT THAT THE RIDGE SHOULD STEER
KARL GENERALLY WEST-NORTHWESTWARD ACROSS THE YUCATAN PENINSULA INTO
THE SOUTHWESTERN GULF OF MEXICO...FOLLOWED BY A GENERAL WESTWARD
MOTION TOWARD MAINLAND MEXICO.  THERE IS SOME SPREAD IN THE TRACK
GUIDANCE OVER THE GULF OF MEXICO...WITH SOME OF THE DYNAMICAL
MODELS FORECASTING A SOUTH-OF-WEST MOTION BEFORE KARL REACHES THE
COAST OF MAINLAND MEXICO.  THE FORECAST TRACK WILL SHOW A WESTWARD
MOTION AFTER 72 HR...AND OVERALL IT LIES DOWN THE CENTER OF THE
GUIDANCE ENVELOPE.
 
KARL IS IN AN ENVIRONMENT OF LIGHT EASTERLY VERTICAL WIND SHEAR...
AND THIS IS FORECAST TO PERSIST FOR THE NEXT 4-5 DAYS.  THE MAJOR
INFLUENCE ON THE INTENSITY WILL BE LAND INTERACTION.  WHILE THE
INTENSITY FORECAST SHOWS KARL WITH 45-KT WINDS OVER EASTERN
YUCATAN...THE STORM COULD REACH A HIGHER INTENSITY BETWEEN THE 12
AND 24 HR FORECAST POINTS.  OVER THE GULF OF MEXICO...KARL SHOULD
RE-INTENSIFY...WITH THE SHIPS AND GFDL MODELS CALLING FOR IT TO
BECOME A HURRICANE.  THE INTENSITY FORECAST IS A BIT MORE
CONSERVATIVE DUE TO UNCERTAINTY ABOUT WHAT KIND OF STRUCTURE KARL
WILL HAVE AFTER CROSSING THE YUCATAN PENINSULA.  AFTER FINAL
LANDFALL IN MEXICO...KARL SHOULD EVENTUALLY DISSIPATE OVER THE
MOUNTAINS OF CENTRAL MEXICO.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      14/2100Z 18.3N  84.2W    35 KT
 12HR VT     15/0600Z 18.9N  86.0W    40 KT
 24HR VT     15/1800Z 19.6N  88.1W    45 KT...INLAND
 36HR VT     16/0600Z 20.4N  90.3W    30 KT...INLAND
 48HR VT     16/1800Z 21.0N  92.6W    35 KT...OVER WATER
 72HR VT     17/1800Z 21.5N  96.0W    55 KT
 96HR VT     18/1800Z 21.5N  99.5W    30 KT...INLAND
120HR VT     19/1800Z...DISSIPATED
 
$$
FORECASTER BEVEN