Origins Meteorological history of Hurricane Dennis

tropical depression 4 upon classification tropical cyclone on july 4, north of tobago.

on june 26, 2005, national hurricane center (nhc) began monitoring tropical wave well-inland on africa. feature tracked via radiosonde observations various nations 2 days before being analyzed surface feature on june 28 on western senegal. accompanied scattered convection—shower , thunderstorm activity—the westward moving system featured cyclonic flow; emerged on atlantic ocean on june 29. conflicting observations dakar, senegal, made tracking wave difficult, surface observations revealing clear shift in wind direction , upper-level soundings showing no change. regardless of exact position of system, accompanying convection diminished , system became ill-defined. june 30, system grew , multiple low-level circulations developed within broader cyclonic envelope. weather models @ time depicted low probability of tropical cyclogenesis in subsequent days. gradual development ensued on following days, though broad circulation remained largely devoid of convection due dry air associated saharan air layer.

two distinct low-level centers became apparent on july 2 overall system progressed west. surface observations windward islands , guyana depicted broad circulation; however, satellite animations failed show defined center, inhibiting classification tropical cyclone. westernmost of 2 centers moved across windward islands on july 4 , lost organization thereafter. banding features developed eastern circulation throughout day, consolidating around 1012 mbar (hpa; 29.89 inhg) low. later on july 4, upper-level outflow—an anticyclonic feature provides thermal ventilation tropical cyclones , allows further development—became increasingly prominent. continued organization, nhc classified system tropical depression 4 @ 18:00 utc @ time situated 65 mi (105 km) east of st. george s, grenada.