| HOME | ARCHIVES | FORECASTS | IMAGERY | ABOUT NHC | RECONNAISSANCE |

---

Tropical Depression TWO (Text)

ZCZC MIATCDAT2 ALL
TTAA00 KNHC DDHHMM
 
TROPICAL DEPRESSION TWO DISCUSSION NUMBER   1
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL022011
500 PM EDT SUN JUL 17 2011

AN AIR FORCE HURRICANE HUNTER PLANE INVESTIGATING THE LOW PRESSURE
AREA JUST NORTH OF THE NORTHWEST BAHAMAS FOUND A WELL-DEFINED
LOW-LEVEL CENTER OF CIRCULATION...AND THE SYSTEM IS BEING
DESIGNATED AS A TROPICAL CYCLONE AT THIS TIME.  ALTHOUGH WINDS OF
TROPICAL STORM FORCE WERE MEASURED BY THE SFMR INSTRUMENT ON BOARD
THE PLANE...THESE OBSERVATIONS WERE FLAGGED AS QUESTIONABLE.  PEAK
FLIGHT-LEVEL WINDS REPORTED BY THE AIRCRAFT WERE 44 KT WHICH WOULD
NORMALLY INDICATE A SYSTEM OF TROPICAL STORM STRENGTH.  HOWEVER...
THE CONVECTION NEAR THE CENTER IS RELATIVELY WEAK...AND IN THIS
CASE THE STRONGEST WINDS ARE LIKELY NOT MIXING DOWN TO THE SURFACE
AS MUCH AS TYPICALLY OCCURS.  THE CURRENT INTENSITY ESTIMATE IS 30
KT.  THE ATMOSPHERIC ENVIRONMENT IS NOT IDEAL FOR STRENGTHENING
WITH SOME DRIER AIR JUST TO THE NORTH AND NORTHWEST OF THE CYCLONE. 
THE OFFICIAL INTENSITY FORECAST CLOSELY FOLLOWS THE LGEM AND
INTENSITY CONSENSUS GUIDANCE.  NONE OF THE CURRENT MODEL RUNS SHOW
THE SYSTEM STRENGTHENING INTO A HURRICANE.

INITIAL MOTION IS A SOUTHWARD DRIFT.  STEERING CURRENTS ARE LIKELY
TO REMAIN QUITE WEAK OVER THE NEXT DAY OR SO...AS THE SYSTEM IS
SITUATED IN A WEAKNESS IN THE SUBTROPICAL RIDGE.  IN A COUPLE
OF DAYS...THE MID-LEVEL RIDGE TO THE SOUTHEAST OF THE TROPICAL
CYCLONE IS FORECAST TO STRENGTHEN SLIGHTLY AND THIS...ALONG WITH A
WEAK TROUGH PASSING NORTH OF THE CYCLONE...SHOULD INDUCE A GENERAL
NORTHEASTWARD MOTION.  LATER IN THE FORECAST PERIOD...THE TRACK
GUIDANCE IS IN FAIRLY GOOD AGREEMENT ON AN EAST-NORTHEASTWARD
MOTION AT AN INCREASING FORWARD SPEED.  THE OFFICIAL FORECAST IS
RATHER CLOSE TO THE MODEL CONSENSUS AND TO THE LATEST ECMWF TRACK.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  17/2100Z 27.5N  78.2W   30 KT  35 MPH
 12H  18/0600Z 27.4N  78.2W   40 KT  45 MPH
 24H  18/1800Z 28.2N  77.8W   45 KT  50 MPH
 36H  19/0600Z 29.0N  77.3W   50 KT  60 MPH
 48H  19/1800Z 30.4N  76.5W   50 KT  60 MPH
 72H  20/1800Z 32.0N  73.5W   50 KT  60 MPH
 96H  21/1800Z 34.0N  67.0W   45 KT  50 MPH
120H  22/1800Z 36.0N  60.0W   40 KT  45 MPH
 
$$
FORECASTER PASCH/STEWART
 
NNNN