Currently, most of the eastern United States is dominated by a longwave ridge at 500 hPa ahead of a longwave trough centered over the Midwest. The ridge is associated with surface high pressure centered over the mid-Atlantic while the trough is associated with a frontal system over the Great Lakes. The high pressure that has been driving weather in Stony Brook the last few days will move offshore overnight as the trough deepens and moves east with the frontal system, pushing the high pressure offshore. This will result in clouds increasing and winds becoming more southwesterly in Stony Brook as the low temperature drops to around 40F. On Friday the frontal system will bring about 0.03 inches of rain to Stony Brook starting in the afternoon. The Friday high temperature will be around 47F and winds will shift to being from the southeast.