Subseasonal monitoring and forecasting must consider effects from multiple time/space scale interactions. Weather prediction models include such interactions, but model error and initial condition errors preclude an exclusive dependence on them.

A synoptic model consisting of three time scales is proposed and is applied to the 2001-02 (DJF) winter period. The three time scales are a 30-70 day quasi-osicllation that primarily represents the Madden-Julian oscillation, a 10-60 day band that represents midlatitude interactions such as teleconnection patterns and zonal index cycle variations (~5-10 day decorrelation time scale), and a less than 10 day band to represent storms and baroclinic wave packets (~1-2 day decorrelation time). The latter spread information around the northern hemisphere in less than 10 days. A unique feature of the model is its focus on transitions and extreme events. Tropical-extratropical interaction during the January 30-31, 2002 ice storm over the U.S. central Plains will be described. The atmospheric angular momentum budget provides a useful quantitative monitoring framework for the synoptic model, including the role of mountains and surface zonal wind stresses.