Tropical Storm LORENZO

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TROPICAL STORM LORENZO DISCUSSION NUMBER   3
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL132013
1100 PM AST MON OCT 21 2013
 
ALTHOUGH LORENZO CONTINUES TO PRODUCE A WELL-DEFINED CURVED
BAND...THE LOW-LEVEL CENTER IS DISPLACED FROM THE DEEP CONVECTION
AS A RESULT OF 15 KT OF WESTERLY SHEAR.  THE INITIAL INTENSITY
REMAINS 35 KT BASED ON SATELLITE ESTIMATES OF T2.5/35 KT FROM TAFB
AND T2.0/30 KT FROM SAB...AND TWO RECENT ASCAT PASSES WHICH SHOWED
MAXIMUM WINDS BETWEEN 30 AND 35 KT.  ALL INDICATIONS ARE THAT THE
DEEP-LAYER SHEAR AFFECTING LORENZO SHOULD TURN NORTH-NORTHWESTERLY
AND INCREASE TO NEAR 30 KT BY 36 HOURS...WHICH WOULD ALSO HELP
DRIER AIR TO THE WEST OF THE CYCLONE TO INFILTRATE THE CIRCULATION. 
THEREFORE...THE INTENSITY IS EXPECTED TO BE NEARLY STEADY DURING
THE NEXT 36 HOURS AND THEN DECREASE THEREAFTER.  THE SHEAR...COLDER
WATER...AND DRIER AIR SHOULD CAUSE LORENZO TO DEGENERATE TO A
REMNANT LOW AND DISSIPATE IN 3 TO 4 DAYS.  IF THE ECMWF AND UKMET
MODEL SOLUTIONS HOLD TRUE...LORENZO COULD DISSIPATE ABOUT A DAY
EARLIER THAN INDICATED IN THE NHC FORECAST.
 
RECENT FIXES INDICATE THAT LORENZO HAS TURNED NORTHEASTWARD WITH AN
INITIAL MOTION OF 055/8 KT.  THE CYCLONE IS LOCATED ALONG THE
SOUTHERN PERIPHERY OF THE MID-LATITUDE WESTERLIES BUT JUST OUTSIDE
OF THE STRONGEST STEERING FLOW.  THEREFORE...LORENZO IS FORECAST TO
MOVE EAST-NORTHEASTWARD TO EASTWARD AND MAINTAIN A CONSTANT SPEED
DURING THE NEXT 36 HOURS...AND THEN TURN BACK TO THE NORTHEAST AND
ACCELERATE JUST BEFORE DISSIPATION.  THE UPDATED NHC TRACK FORECAST
HAS BEEN SHIFTED A BIT SOUTH OF THE PREVIOUS ONE BUT NOT QUITE AS
FAR SOUTH AS THE MULTI-MODEL CONSENSUS TVCA.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  22/0300Z 29.3N  53.8W   35 KT  40 MPH
 12H  22/1200Z 29.7N  52.6W   40 KT  45 MPH
 24H  23/0000Z 29.9N  50.9W   40 KT  45 MPH
 36H  23/1200Z 30.2N  49.6W   40 KT  45 MPH
 48H  24/0000Z 30.7N  48.5W   35 KT  40 MPH
 72H  25/0000Z 32.5N  45.5W   25 KT  30 MPH...POST-TROP/REMNT LOW
 96H  26/0000Z...DISSIPATED
 
$$
FORECASTER BERG
 
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