000
WTNT45 KNHC 092037
TCDAT5
 
TROPICAL STORM NATE DISCUSSION NUMBER   9
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL152011
400 PM CDT FRI SEP 09 2011
 
THE HURRICANE HUNTER AIRCRAFT INVESTIGATING NATE THIS AFTERNOON
FOUND A PEAK 850-MB FLIGHT-LEVEL WIND OF 55 KT AND PEAK SFMR VALUES
OF 40-45 KT. BASED ON THIS...THE INITIAL INTENSITY IS SET AT 45 KT
FOR THIS ADVISORY. WHILE NATE CONTINUES TO HAVE AN IMPRESSIVE
BANDED STRUCTURE IN VISIBLE IMAGERY...DEEP CONVECTION IS
LACKING...BUT HAS MADE A BIT OF A COMEBACK IN THE PAST HOUR OR TWO
IN RAINBANDS WELL EAST AND WEST OF THE CENTER. THE SHIPS MODEL
ANALYSIS CONTINUES TO SHOW RELATIVELY DRY AIR IN THE MID-LEVELS AND
AND A LACK OF INSTABILITY IN THE PROFILE. HOWEVER...GIVEN THE VERY
WARM SSTS OVER THE SOUTHWESTERN GULF OF MEXICO...NATE SHOULD BE
ABLE TO INTENSIFY SOME IF CAN RE-ESTABLISH CONVECTION NEAR THE
CENTER. GIVEN THE RECENT WEAKENING TREND THE STATISTICAL MODELS
SHOW ONLY GRADUAL STRENGTHENING UNTIL LANDFALL WHILE THE DYNAMICAL
MODELS ARE A LITTLE MORE AGGRESSIVE...BUT STILL LOWER THAN THE LAST
CYCLE. THE OFFICIAL FORECAST HAS BEEN ADJUSTED DOWNWARD BY ABOUT 10
KT COMPARED TO THE PREVIOUS PACKAGE BUT IS ABOVE MOST OF THE
GUIDANCE. AFTER LANDFALL NATE SHOULD QUICKLY WEAKEN OVER THE HIGH
TERRAIN AND DISSIPATE BY 96 HOURS.
 
AFTER APPEARING TO MOVE WEST-NORTHWESTWARD EARLIER TODAY...THE
LATEST AIRCRAFT FIXES SUGGEST NATE HAS BEEN NEARLY STATIONARY. 
MODEL GUIDANCE CONTINUES TO SUGGEST THAT A MID-LEVEL RIDGE WILL
REBUILD TO THE NORTH OF NATE OVER THE NEXT DAY OR TWO...WHICH
SHOULD GET NATE MOVING AGAIN. THE GFS...HWRF...AND GFDL MODELS NOW
SHOW MORE OF A TURN TOWARD THE WEST-SOUTHWEST AS NATE APPROACHES
THE COAST...WHILE THE ECMWF AND UKMET SHOW A MORE WESTWARD TRACK.
THE OFFICIAL FORECAST HAS BEEN SHIFTED SOUTHWARD FOR THIS CYCLE BUT
STILL LIES NORTH OF THE MULTI-MODEL CONSENSUS...SHOWING A SLOW
WESTWARD MOTION FOR 12 TO 24 HOURS AND A TURN SOUTH OF DUE WEST
PRIOR TO LANDFALL. 
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  09/2100Z 20.0N  92.8W   45 KT  50 MPH
 12H  10/0600Z 20.2N  93.4W   50 KT  60 MPH
 24H  10/1800Z 20.2N  94.1W   60 KT  70 MPH
 36H  11/0600Z 20.1N  95.0W   65 KT  75 MPH
 48H  11/1800Z 20.0N  96.0W   70 KT  80 MPH
 72H  12/1800Z 19.5N  98.5W   35 KT  40 MPH...INLAND
 96H  13/1800Z...DISSIPATED
 
$$
FORECASTER BRENNAN