[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT42 KNHC 140240
TCDAT2

TROPICAL DEPRESSION SEVEN DISCUSSION NUMBER   1
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL072011
1100 PM EDT SAT AUG 13 2011

SATELLITE IMAGERY INDICATES THAT THE LOW PRESSURE AREA
SOUTH-SOUTHEAST OF BERMUDA HAS DEVELOPED PERSISTENT CENTRAL
CONVECTION AROUND A TIGHTLY-WOUND LOW-LEVEL CENTER.  SATELLITE
INTENSITY ESTIMATES FROM SAB AND TAFB ARE 30 KT...AND BASED ON THESE
ADVISORIES ARE INITIATED ON THE SYSTEM AS TROPICAL DEPRESSION
SEVEN.

THE INITIAL MOTION IS 290/9.  THE DEPRESSION IS CURRENTLY ON THE
SOUTHWEST SIDE OF A LARGE LOW-/MID-LEVEL RIDGE OVER THE CENTRAL
NORTH ATLANTIC.  A DEEP-LAYER TROUGH ADVANCING INTO THE THE EASTERN
UNITED STATES AND THE NORTHWESTERN ATLANTIC WILL BREAK DOWN THE
WESTERN END OF THE RIDGE...CAUSING THE DEPRESSION TO TURN NORTHWARD
BY 36 HR AND RECURVE NORTHEASTWARD INTO THE WESTERLIES BY 72 HR.
THE FORECAST TRACK FOLLOWS THIS SCENARIO...WITH THE FORECAST BEING
A BLEND OF THE ECMWF AND GFDL MODEL FORECASTS.  A POTENTIAL
COMPLICATION TO THE TRACK FORECAST IS SHOWN BY THE UKMET MODEL...
WHICH FORECASTS THE DEPRESSION TO EXPERIENCE ERRATIC MOTION DURING
THE NEXT 48 HR AS IT INTERACTS WITH A DISTURBANCE CURRENTLY ABOUT
400 N MI TO THE SOUTHEAST.   IF SUCH INTERACTION OCCURS...IT WOULD
DELAY THE APPROACH OF THE DEPRESSION TO BERMUDA.

WATER VAPOR IMAGERY SHOWS SMALL UPPER-LEVEL LOWS TO THE SOUTHWEST
AND NORTHEAST OF THE DEPRESSION.  THESE SYSTEMS ARE HELPING TO
PRODUCE LIGHT NORTHWESTERLY VERTICAL WIND SHEAR...AS WELL AS
ADVECTING UPPER-LEVEL DRY AIR INTO THE DEPRESSION.  IN ADDITION...
A LARGE PLUME OF AFRICAN DUST AND ASSOCIATED DRY AIR ARE
APPROACHING THE DEPRESSION FROM THE EAST.  WHILE VERTICAL SHEAR
SHOULD BE LIGHT ENOUGH FOR THE NEXT 48 HR TO ALLOW DEVELOPMENT...
THE ABUNDANT DRY AIR AROUND THE SYSTEM SHOULD AT LEAST SLOW
INTENSIFICATION.  THE INTENSITY FORECAST CALLS FOR GRADUAL
STRENGTHENING THROUGH 48 HR WHILE THE CYCLONE REMAINS OVER WARM
WATER.  AFTER 72 HR...THE CYCLONE IS EXPECTED TO BE ABSORBED INTO A
FRONTAL SYSTEM OVER THE FAR NORTH ATLANTIC.

THE FORECAST TRACK AND WIND RADII REQUIRE A TROPICAL STORM WATCH FOR
BERMUDA AT THIS TIME.  A TROPICAL STORM WARNING WILL LIKELY BE
REQUIRED SOMETIME ON SUNDAY.


FORECAST POSITIONS AND MAX WINDS

INIT  14/0300Z 27.9N  61.6W   30 KT  35 MPH
 12H  14/1200Z 28.6N  62.6W   35 KT  40 MPH
 24H  15/0000Z 30.1N  63.7W   40 KT  45 MPH
 36H  15/1200Z 32.0N  64.0W   45 KT  50 MPH
 48H  16/0000Z 35.0N  63.0W   50 KT  60 MPH
 72H  17/0000Z 43.0N  55.0W   50 KT  60 MPH
 96H  18/0000Z...ABSORBED BY FRONTAL SYSTEM

$$
FORECASTER BEVEN


This weather bulletin was brought to you by:
www.nashvilleweather.net