Tropical Depression FIVE

ZCZC MIATCDAT5 ALL
TTAA00 KNHC DDHHMM
 
TROPICAL DEPRESSION FIVE DISCUSSION NUMBER   2
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL052013
500 AM AST THU AUG 15 2013

SATELLITE IMAGERY THIS MORNING SUGGESTS THAT TROPICAL DEPRESSION
FIVE IS GETTING BETTER ORGANIZED.  A CONVECTIVE CLUSTER WITH TOPS
COLDER THAN -80C HAS FORMED NEAR AND TO THE WEST OF THE CENTER...AND
THERE IS OUTER BANDING IN THE SOUTHEASTERN SEMICIRCLE.  SATELLITE
INTENSITY ESTIMATES FROM TAFB AND SAB ARE BELOW TROPICAL STORM
STRENGTH...SO THE CYCLONE WILL REMAIN A 30-KT DEPRESSION FOR THIS
ADVISORY.  HOWEVER...THIS INTENSITY COULD BE A LITTLE CONSERVATIVE.

THE INITIAL MOTION IS 290/14.  THE DEPRESSION IS CURRENTLY ON THE
SOUTH SIDE OF A LOW/MID-LEVEL RIDGE OVER THE EASTERN ATLANTIC...AND
THE TRACK GUIDANCE IS IN GOOD AGREEMENT THAT THIS WILL STEER THE
CYCLONE WEST-NORTHWESTWARD FOR THE NEXT 2-3 DAYS.  AFTER THAT...THE
GUIDANCE DIVERGES.  THE GFS...THE GFS ENSEMBLE MEAN...AND THE
CANADIAN MODELS SHOW THE SYSTEM TURNING WESTWARD.  THE ECMWF...THE
UKMET...AND THE GFDL SHOW A WEST-NORTHWESTWARD TO NORTHWESTWARD
MOTION...WITH THE CYCLONE MOVING TOWARD A WEAKNESS IN THE RIDGE
OVER THE CENTRAL ATLANTIC.  OVERALL...THE GUIDANCE ENVELOPE HAS
SHOWN A NORTHWARD SHIFT SINCE THE LAST ADVISORY.  SINCE THE CYCLONE
IS EXPECTED TO WEAKEN AND BE STEERED BY THE LOW-LEVEL FLOW DURING
THIS TIME...THE NEW FORECAST TRACK SHOWS A WESTWARD TURN IN BEST
AGREEMENT WITH THE GFS.  WHILE THE NEW FORECAST TRACK IS A LITTLE
NORTH OF THE PREVIOUS TRACK AFTER 48 HR...IT IS WELL TO THE SOUTH
OF THE ECMWF...THE UKMET...THE GFDL...AND THE CONSENSUS MODELS.

THE DEPRESSION IS CURRENTLY IN AN ENVIRONMENT OF WARM SEA SURFACE
TEMPERATURES AND LIGHT VERTICAL WIND SHEAR.  THIS SHOULD ALLOW SOME
STRENGTHENING UNTIL THE SYSTEM REACHES COOLER WATERS IN 48 HR OR
SO.  WHILE THE CYCLONE IS FORECAST TO LEAVE THE COOLER WATERS AFTER
THAT TIME...THE GFS...ECMWF...AND UKMET ARE IN GOOD AGREEMENT THAT
IT SHOULD ENCOUNTER VERY DRY AIR AND WEAKEN...WITH THESE MODELS
SHOWING THE SYSTEM DEGENERATING TO A TROPICAL WAVE BY 120 HR.  THE
NEW INTENSITY FORECAST DOES NOT YET FOLLOW THAT SCENARIO...AS THE
SHIPS AND LGEM MODELS SHOW A STEADY-STATE OR STRENGTHENING SYSTEM. 
INSTEAD...THE FORECAST CALLS FOR A SLOW WEAKENING AS A COMPROMISE
BETWEEN THESE EXTREMES.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  15/0900Z 14.4N  25.2W   30 KT  35 MPH
 12H  15/1800Z 15.0N  27.2W   35 KT  40 MPH
 24H  16/0600Z 15.7N  30.0W   40 KT  45 MPH
 36H  16/1800Z 16.4N  32.6W   45 KT  50 MPH
 48H  17/0600Z 17.2N  35.0W   50 KT  60 MPH
 72H  18/0600Z 18.0N  39.5W   50 KT  60 MPH
 96H  19/0600Z 18.0N  43.5W   45 KT  50 MPH
120H  20/0600Z 18.0N  48.5W   40 KT  45 MPH
 
$$
FORECASTER BEVEN
 
NNNN