The convective phase of the Madden Julian oscillation stretched across the eastern tropical Pacific Ocean and into the western Atlantic tropics (phase_8/phase_1) the past 7-10 days with moderate-to-strong intensity. The result is widespread tropical convection spawning many tropical events (4 in both the East Pacific and North Atlantic tropics including Elida, Fausto, Genevieve and Isaias plus several potent tropical disturbances). The latent heat release poleward of the tropical convection and the attendant tropical systems into the middle atmosphere of the middle latitudes amplified a high pressure ridge in the Western U.S. causing the California heat wave.

Occasionally, NOAA/CPC long-lead forecasts will produce relatively bold probabilities in extended-range forecasts. If so, risk managers interested in possible adverse climate conditions should take note. The NOAA/CPC outlook for meteorological summer (from last February) indicated an unusually wet probability (given the 3.5 to 6.5 lead time) across Virginia which has certainly verified given the historic rainfall observed in August.

On June 29, 2012 a derecho surged east-southeast from the Ohio Valley across the Mid-Atlantic region causing widespread wind damage resulting in the loss of 4,000,000 people without power. Yesterday a similarly intense derecho moved rapidly across the Midwest U.S. knocking out power to over 500,000 people.

Steady pulses of African dust continue to emit westward in the North Atlantic tropics suppressing tropics cyclone activity. However, the relative humidity/available moisture at mid-level atmosphere is increasing. The mid-level atmosphere increased humidity is very supportive of the tropics starting to percolate.