482 
 WTPZ42 KNHC 171444
 TCDEP2
  
 TROPICAL STORM GREG DISCUSSION NUMBER   4
 NWS NATIONAL HURRICANE CENTER MIAMI FL       EP072011
 800 AM PDT WED AUG 17 2011
 
 SATELLITE IMAGERY INDICATES THAT GREG HAS STRENGTHENED THIS MORNING 
 AS A CENTRAL DENSE OVERCAST HAS DEVELOPED WITH AN OUTER CONVECTIVE
 BAND OVER THE NORTHWESTERN SEMICIRCLE.  SATELLITE INTENSITY
 ESTIMATES ARE 55 KT FROM TAFB AND 35 KT FROM SAB...SO THE INITIAL
 INTENSITY IS INCREASED TO 45 KT.  ANALYSES FROM CIMSS AT THE
 UNIVERSITY OF WISCONSIN SHOW 10-15 KT OF NORTHEASTERLY VERTICAL
 WIND SHEAR STILL AFFECTING THE STORM...AND RECENT MICROWAVE DATA
 SUPPORTS THIS BY SHOWING A SOMEWHAT SHEARED PATTERN TO THE
 CONVECTION UNDERNEATH THE CDO.
  
 THE INITIAL MOTION IS NOW 300/18...WHICH IS FASTER THAN BEFORE. 
 GREG IS LOCATED BETWEEN A LARGE MID/UPPER-LEVEL RIDGE OVER THE
 SOUTHERN UNITED STATES AND NORTHERN MEXICO AND A LARGE BUT WEAK
 TROPICAL DISTURBANCE TO ITS WEST AND SOUTHWEST.  DURING THE NEXT
 COUPLE OF DAYS...THE DISTURBANCE IS FORECAST TO WEAKEN DUE TO ITS
 PROXIMITY TO GREG...LEAVING THE RIDGE TO THE NORTH AS THE MAIN
 STEERING MECHANISM.  THIS EVOLUTION SHOULD STEER THE STORM QUICKLY
 TOWARD THE WEST-NORTHWEST FOR 24 HR OR SO...FOLLOWED BY A GRADUAL
 TURN TOWARD THE WEST AND A DECREASE IN FORWARD SPEED.  THE TRACK
 GUIDANCE FOLLOWS THIS SCENARIO...ALTHOUGH THERE HAS BEEN A
 NORTHWARD SHIFT LIKELY DUE TO THE INITIAL POSITION AND MOTION.  THE
 NEW FORECAST TRACK IS FASTER THAN AND A LITTLE TO THE NORTH OF THE
 PREVIOUS FORECAST...AND IT LIES CLOSE TO THE VARIOUS CONSENSUS
 MODELS.
 
 THE FORECAST TRAVCK KEEPS GREG OVER SEA SURFACE TEMPERATURES OF 27C
 OR WARMER FOR 36 HR...AND THE DYNAMICAL MODELS FORECAST THE SHEAR
 TO DECREASE DURING THIS TIME.  THIS COMBINATION SHOULD ALLOW
 CONTINUED STRENGTHENING...AND THE NEW INTENSITY FORECAST CALLS FOR
 A PEAK INTENSITY OF 75 KT IN 36 HR AS A BLEND BETWEEN THE SHIPS AND
 LGEM MODELS.  AFTER 48 HR...THE WATERS GET COOLER ON THE FORECAST
 TRACK...WHICH SHOULD INDUCE A STEADY WEAKENING TREND.
  
 FORECAST POSITIONS AND MAX WINDS
  
 INIT  17/1500Z 16.7N 104.2W   45 KT  50 MPH
  12H  18/0000Z 17.7N 106.6W   55 KT  65 MPH
  24H  18/1200Z 18.4N 109.4W   65 KT  75 MPH
  36H  19/0000Z 19.0N 111.8W   75 KT  85 MPH
  48H  19/1200Z 19.4N 113.6W   75 KT  85 MPH
  72H  20/1200Z 20.0N 116.5W   65 KT  75 MPH
  96H  21/1200Z 20.5N 119.0W   45 KT  50 MPH
 120H  22/1200Z 20.5N 122.0W   30 KT  35 MPH
  
 $$
 FORECASTER BEVEN