929 
 WTNT42 KNHC 041432
 TCDAT2
  
 TROPICAL STORM KAREN DISCUSSION NUMBER   6
 NWS NATIONAL HURRICANE CENTER MIAMI FL       AL122013
 1000 AM CDT FRI OCT 04 2013
  
 AFTER BEING DISPLACED WELL EAST OF THE LOW-LEVEL CENTER OF KAREN...
 DEEP CONVECTION HAS RECENTLY DEVELOPED A LITTLE CLOSER TO THE
 CENTER OVER THE PAST HOUR OR TWO...BUT THE CYCLONE IS STILL BEING
 AFFECTED BY 20-25 KT OF WESTERLY SHEAR AND DRY AIR BEING ADVECTED
 INTO THE CYCLONE. THE LAST CENTRAL PRESSURE REPORTED BY THE
 AIRCRAFT WAS 1003 MB...AND BASED ON THE LATEST ROUND OF AIRCRAFT
 DATA THE INTENSITY HAS BEEN REDUCED TO 45 KT. THE ENVIRONMENT DOES
 NOT LOOK FAVORABLE FOR SIGNIFICANT INTENSIFICATION...WITH MODERATE
 SHEAR EXPECTED TO CONTINUE FOR THE NEXT DAY OR TWO. HOWEVER...IF
 THE SHEAR DOES LESSEN...EVEN FOR A SHORT PERIOD OF TIME...DEEP
 CONVECTION COULD RE-DEVELOP CLOSER TO THE CENTER AND ALLOW FOR SOME
 INTENSIFICATION. IN ADDITION...BY 48 HOURS UPPER-LEVEL DIVERGENCE
 AHEAD OF AN APPROACHING MID/UPPER-LEVEL TROUGH COULD ALLOW FOR SOME
 STRENGTHENING. THE NEW NHC INTENSITY FORECAST HAS BEEN ADJUSTED
 DOWNWARD AND SHOWS LITTLE CHANGE IN THE NEXT 24 HOURS AND A
 STRENGTHENING TO 55 KT BY 48 HOURS.
  
 THE INITIAL MOTION HAS BEEN WOBBLING BETWEEN 325 AND 330 DEGREES AT
 ABOUT 9 OR 10 KT OVER THE PAST FEW HOURS. THE FUTURE TRACK WILL BE
 QUITE SENSITIVE TO THE STRUCTURE OF KAREN OVER THE NEXT COUPLE OF
 DAYS. IN THE SHORT TERM A WEAKER SHALLOWER SYSTEM WILL BE STEERED
 MORE TOWARD THE LEFT BY THE LOW-LEVEL FLOW...WHILE A DEEPER MORE
 VERTICALLY COHERENT CYCLONE WOULD TURN NORTHWARD MORE QUICKLY DUE
 TO A MID-LEVEL RIDGE TO THE EAST. GIVEN THE CURRENT APPEARANCE OF
 KAREN AND THE CONTINUED SHEAR...THE NHC TRACK HAS BEEN ADJUSTED A
 LITTLE TO THE LEFT DURING THE FIRST 24 HOURS TOWARD THE UKMET AND
 ECMWF MODELS...WHICH SHOW A WEAKER SYSTEM. ALL OF THE GUIDANCE
 SHOWS A NORTHEASTWARD TURN IN 36 TO 48 HOURS...BUT WITH LARGE
 DIFFERENCES IN THE LATITUDE AT WHICH THE TURN OCCURS AND
 SIGNIFICANT SPREAD IN WHERE THE CENTER CROSSES THE COAST. AT 36
 HOURS AND BEYOND THE NHC TRACK IS CLOSE TO THE ECMWF AND THE
 MULTI-MODEL CONSENSUS...AND CLOSE TO THE PREVIOUS OFFICIAL
 FORECAST. GIVEN THE LARGE SPREAD AND THE DEPENDENCE OF THE TRACK ON
 THE STRUCTURE AND INTENSITY OF KAREN...CONFIDENCE IN THE DETAILS OF
 THE TRACK FORECAST...AND THEREFORE THE DISTRIBUTION OF IMPACTS
 ALONG THE COAST...IS LOW.
  
 THE NOAA GULFSTREAM-IV JET SAMPLED THE ENVIRONMENT NEAR KAREN AND
 OVER THE NORTHERN GULF OF MEXICO OVERNIGHT. THESE DATA WILL BE
 INCORPORATED INTO THE 12Z MODEL CYCLE...AND HOPEFULLY IMPROVE THE
 ANALYSIS OF THE ENVIRONMENT NEAR AND AHEAD OF THE STORM.
  
 GIVEN THE WESTWARD SHIFT IN THE NHC TRACK...THE TROPICAL STORM
 WARNING HAS BEEN EXTENDED WESTWARD TO MORGAN CITY LOUISIANA. GIVEN
 THE WEAKENING TREND AND THE REDUCTION IN THE INTENSITY FORECAST...IT
 HAS BECOME A LITTLE LESS LIKELKY THAT KAREN WILL REACH HURRICANE
 STRENGTH. IF THESE TRENDS CONTINUE...THE HURRICANE WATCH COULD BE
 CHANGED TO A TROPICAL STORM WATCH OR WARNING LATER TODAY. 
  
 FORECAST POSITIONS AND MAX WINDS
  
 INIT  04/1500Z 25.6N  90.2W   45 KT  50 MPH
  12H  05/0000Z 26.6N  90.7W   45 KT  50 MPH
  24H  05/1200Z 27.7N  90.9W   45 KT  50 MPH
  36H  06/0000Z 28.6N  90.5W   50 KT  60 MPH
  48H  06/1200Z 29.8N  88.6W   55 KT  65 MPH
  72H  07/1200Z 33.5N  83.0W   25 KT  30 MPH...POST-TROP/EXTRATROP
  96H  08/1200Z...ABSORBED
  
 $$
 FORECASTER BRENNAN