Forecasting the motion of North Atlantic tropical cyclones by the objective MOHATT scheme

摘要

An objective scheme for forecasting themotion of tropical cyclones (MOHATT) , under developmentsince 1967 by the U.S. Navy Fleet NumericalWeather Central and the U.S. Naval Postgraduate School,Monterey, Calif., is described and applied to the 1967-71North Atlantic tropical cyclones for forecast intervals upto 72 hr. The MOHATT scheme involves steering of thecenter of the cyclone by geostrophic winds derived fromheavily smoothed isobaric height fields (both analyzed andprognostic) and a statistical correction determined by thebehavior of the first 12 hr of the steering forecast. Thedevelopmental sample (1967-70) used to establish thepotential accuracy of MOHATT indicates 700 mb as theoptimum steering level, but the fully operational test in1971 suggests that the 850-mb level may be an improvementfor forecast intervals beyond 36 hr.