[Tropical] Tropical Cyclone Discussion

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WTNT45 KNHC 100251
TCDAT5

TROPICAL STORM NATE DISCUSSION NUMBER  10
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL152011
1000 PM CDT FRI SEP 09 2011

THERE HAS NOT BEEN A LOT OF CHANGE WITH THE STRUCTURE OF NATE DURING
THE PAST SEVERAL HOURS.  ALTHOUGH THE CYCLONE CONTINUES TO HAVE
CURVED BANDING FEATURES ON THE SABANCUY RADAR...THE ASSOCIATED
CONVECTION IS NOT VERY DEEP AND THE CENTER HAS A HOLLOW APPEARANCE
ON INFRARED SATELLITE PICTURES.  THE INITIAL WINDS ARE KEPT AT 45
KT...AND AN AIR FORCE RESERVE PLANE WILL BE IN THE AREA AROUND 0600
UTC TO OBTAIN A BETTER ESTIMATE.

SATELLITE IMAGES SUGGEST THAT NATE HAS MOVED A LITTLE BIT TONIGHT...
WITH AN INITIAL MOTION ESTIMATE OF 280/2.  A RIDGE IS FORECAST TO
BUILD TO THE NORTH OF NATE...CAUSING THE STORM TO ACCELERATE TO THE
WEST TOMORROW.  A FAIR NUMBER OF THE MODELS ALSO SUGGEST A
SOUTH-OF-WEST MOTION COULD OCCUR AS THE CYCLONE APPROACHES
LAND...WHICH IS NOT UNCOMMON IN THAT PART OF THE SOUTHWESTERN GULF
OF MEXICO.  THE NEW NHC TRACK IS ADJUSTED A SMIDGE TO THE SOUTH AND
IS A LITTLE FASTER THAN THE PREVIOUS FORECAST...THOUGH IT REMAINS
TO THE NORTH OF THE MODEL CONSENSUS.

NATE IS YET ANOTHER EXAMPLE OF THE LIMITATIONS OF INTENSITY
FORECASTING.  DESPITE A SEEMINGLY FAVORABLE ENVIRONMENT AND ALL
MODELS SUGGESTING STRENGTHENING...THE STORM HAS LOST ORGANIZATION
SINCE THIS TIME YESTERDAY.  ONE REASON COULD BE THAT THE STATIONARY
SYSTEM HAS UPWELLED COOLER WATERS...CAUSING A LACK OF INSTABILITY
NEAR THE CENTER...WHICH SEEMS LIKE A GOOD POSSIBILITY GIVEN THE
DEARTH OF CENTRAL CONVECTION.   DRY AIR ALOFT ALSO MAY HAVE PLAYED
A ROLE...THOUGH LITTLE EVIDENCE CAN BE SEEN IN SSM/IS VAPOR IMAGES.
IN ANY CASE...NATE IS FORECAST TO MOVE A LITTLE FASTER OVERNIGHT...
WHICH SHOULD BRING THE STORM OVER WARMER WATERS.  WITH LIGHT SHEAR
CONDITIONS LIKELY...SOME INTENSIFICATION IS THE BEST BET.  THE
MODELS DO SHOW STRENGTHENING...THOUGH THEY HAVE BACKED OFF OF THE
PEAK INTENSITY AND ALMOST ALL OF THEM KEEP NATE BELOW HURRICANE
STRENGTH BEFORE LANDFALL.  THIS REDUCTION SEEMS REASONABLE GIVEN
THAT NATE IS FORECAST TO SPEND LESS TIME OVER WATER.  THUS THE
INTENSITY FORECAST IS DECREASED FROM THE PREVIOUS ADVISORY...THOUGH
IT REMAINS ABOVE THE INTENSITY CONSENSUS.


FORECAST POSITIONS AND MAX WINDS

INIT  10/0300Z 20.1N  93.2W   45 KT  50 MPH
 12H  10/1200Z 20.2N  93.8W   45 KT  50 MPH
 24H  11/0000Z 20.1N  94.7W   55 KT  65 MPH
 36H  11/1200Z 20.0N  95.5W   60 KT  70 MPH
 48H  12/0000Z 19.8N  96.8W   55 KT  65 MPH...INLAND
 72H  13/0000Z 19.5N  99.5W   20 KT  25 MPH...POST-TROP/REMNT LOW
 96H  14/0000Z...DISSIPATED

$$
FORECASTER BLAKE/BEVEN


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