000 WTNT45 KNHC 090251 TCDAT5 TROPICAL STORM NATE DISCUSSION NUMBER 6 NWS NATIONAL HURRICANE CENTER MIAMI FL AL152011 1000 PM CDT THU SEP 08 2011 DATA FROM THE MEXICAN RADAR STATION AT SABANCUY INDICATE THAT NATE HAS WELL-DEFINED CURVED BANDS AND OCCASIONALLY IS TRYING TO WRAP UP AN EYE FEATURE. THIS SIGNATURE IS NOT APPARENT ON SATELLITE IMAGERY...WITH THE CONVENTIONAL INFRARED SUGGESTING A WEAKER SYSTEM. THERE IS NOT MUCH EVIDENCE THAT NATE HAS STRENGTHENED SINCE THE AIR FORCE RESERVE RECONNAISSANCE PLANE LEFT THIS EVENING...SO THE INITIAL WINDS WILL REMAIN 60 KT. MEXICAN RADAR DATA SHOW THAT NATE REMAINS STATIONARY...AND IT IS LIKELY TO MOVE LITTLE TONIGHT WHILE IT IS CAUGHT IN AN AREA OF VERY LIGHT STEERING CURRENTS. A RIDGE OVER THE WESTERN CARIBBEAN SEA IS FORECAST TO BUILD TOMORROW...WHICH SHOULD CAUSE NATE TO MOVE MORE TOWARD THE NORTH AND NORTH-NORTHWEST. THERE HAS BEEN A LARGE MODEL CHANGE FROM SIX HOURS AGO...WITH THE GFS/GFDL/HWRF MODELS NOW HAVING A GENERAL WESTWARD TRACK TOWARD MAINLAND MEXICO DUE TO THE CYCLONE BEING TRAPPED BENEATH A NARROW RIDGE OVER THE NORTHERN GULF OF MEXICO. NATE IS FARTHER SOUTH THAN EXPECTED YESTERDAY...SO THE LIKELIHOOD OF A MORE POLEWARD TRACK AHEAD OF THE NEXT TROUGH OVER THE CENTRAL UNITED STATES HAS DIMINISHED. THUS THE NHC FORECAST IS SHIFTED WELL TO THE LEFT AT THIS TIME...BUT BASICALLY ALL RELIABLE MODELS ARE STILL FARTHER TO THE SOUTH. IF CURRENT TRENDS CONTINUE...THE FORECAST WOULD HAVE TO BE ADJUSTED SOUTHWESTWARD AT A LATER TIME. EXCEPT FOR SOME DRY AIR NORTHWEST OF THE CENTER...THE ATMOSPHERIC AND OCEANIC ENVIRONMENT APPEARS FAVORABLE FOR AT LEAST STEADY INTENSIFICATION DURING THE NEXT COUPLE OF DAYS. MOST OF THE GLOBAL MODELS ARE BUILDING AN UPPER ANTICYCLONE OVER NATE... WHICH IS USUALLY QUITE FAVORABLE FOR STRENGTHENING. IT IS A LITTLE SURPRISING THAT NONE OF THE MODELS SHOW NATE BECOMING A MAJOR HURRICANE WITH THIS TYPE OF UPPER-AIR ENVIRONMENT. GIVEN THE PROXIMITY TO LAND AND THE DRY AIR LURKING NEARBY...IT IS PROBABLY BEST NOT TO MAKE TOO LARGE OF A CHANGE TO THE INTENSITY FORECAST AT THIS TIME. THEREFORE...THE NEW NHC FORECAST IS JUST A BIT HIGHER THAN THE PREVIOUS ONE...AT THE UPPER END OF THE GUIDANCE ENVELOPE AND NEAREST THE LGEM MODEL. FORECAST POSITIONS AND MAX WINDS INIT 09/0300Z 19.7N 92.2W 60 KT 70 MPH 12H 09/1200Z 20.0N 92.3W 65 KT 75 MPH 24H 10/0000Z 20.5N 92.7W 75 KT 85 MPH 36H 10/1200Z 21.2N 93.5W 80 KT 90 MPH 48H 11/0000Z 21.7N 94.4W 90 KT 105 MPH 72H 12/0000Z 22.0N 96.5W 85 KT 100 MPH 96H 13/0000Z 21.5N 99.5W 25 KT 30 MPH...INLAND 120H 14/0000Z...DISSIPATED $$ FORECASTER BLAKE