000
WTPZ41 KNHC 170834
TCDEP1
 
TROPICAL STORM FERNANDA DISCUSSION NUMBER   7
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP062011
200 AM PDT WED AUG 17 2011
 
ALTHOUGH THE CLOUD PATTERN CONTINUES TO BE WELL ORGANIZED... DEEP
CONVECTION HAS SIGNIFICANTLY DECREASED IN THE PAST FEW HOURS. SOME
THUNDERSTORM CELLS HAVE RECENTLY BEGUN TO REDEVELOP NEAR THE CENTER
AND WITHIN A CURVED BAND TO THE SOUTHEAST. IT APPEARS THAT THE
NORTHWESTERN HALF OF THE CIRCULATION IS ALREADY BEGINNING TO SPREAD
OVER RELATIVELY COOL WATERS AND STABLE AIR. DVORAK T-NUMBERS HAVE
NOT CHANGED MUCH AND STILL SUPPORT AN INITIAL INTENSITY OF 45
KNOTS. THERE IS SOME ROOM FOR SLIGHT STRENGTHENING AS INDICATED IN
THE OFFICIAL FORECAST BUT IN GENERAL...MOST OF THE LATEST GUIDANCE
NO LONGER BRING FERNANDA TO HURRICANE STATUS. IN THE LATTER PART OF
THE FORECAST PERIOD...SOUTH-SOUTHWESTERLY SHEAR AND COOL WATERS
WILL INDUCE WEAKENING AND...AS IN THE PREVIOUS FORECAST...FERNANDA
SHOULD WEAKEN TO A REMNANT LOW AROUND THAT TIME.
 
FERNANDA IS MOVING TOWARD THE WEST OR 275 DEGREES AT 6 KNOTS.
HOWEVER...GLOBAL MODELS SHOW A WEAKNESS IN THE SUBTROPICAL RIDGE
NEAR 140W LONGITUDE AND THIS PATTERN WILL LIKELY CAUSE THE CYCLONE
TO TURN TOWARD THE WEST-NORTHWEST SOON. BEYOND 4 DAYS...THE
CYCLONE IS EXPECTED TO TURN BACK TO THE WEST AS IT WEAKENS AND
BECOMES STEERED BY THE LOW-LEVEL FLOW. THE TRACK GUIDANCE CONTINUES
TO HAVE A LARGE SPREAD WITH THE HWRF AND GFDL MODELS LYING ON THE
NORTHERN EDGE OF THE DYNAMICAL MODEL SUITE AND GLOBAL MODELS NEAR
THE SOUTHERN EDGE.  THE OFFICIAL FORECAST IS CLOSER TO THE GLOBAL
MODELS.
   
FORECAST POSITIONS AND MAX WINDS
 
INIT  17/0900Z 11.6N 136.9W   45 KT  50 MPH
 12H  17/1800Z 11.7N 138.0W   50 KT  60 MPH
 24H  18/0600Z 12.5N 139.5W   50 KT  60 MPH
 36H  18/1800Z 13.5N 141.0W   50 KT  60 MPH
 48H  19/0600Z 14.5N 142.5W   50 KT  60 MPH
 72H  20/0600Z 15.4N 146.0W   50 KT  60 MPH
 96H  21/0600Z 16.0N 150.0W   35 KT  40 MPH
120H  22/0600Z 16.0N 154.0W   25 KT  30 MPH...POST-TROP/REMNT LOW
 
$$
FORECASTER AVILA