Expect unseasonably warm temperatures today and Thursday across the Mid-Atlantic and Northeast. Afternoon high temperatures in these areas are forecast to be 15 to 30 degrees above average. Temperatures across portions of the Mid-Atlantic are forecast to surpass 80 degrees.
Meanwhile, a slow moving low pressure system will bring the threat for severe thunderstorms today and Wednesday over portions of the South Plains and central Gulf Coast. In addition, a prolonged period of heavy rainfall is expected. Rainfall amounts could exceed 10 inches over portions of the central Gulf Coast and lower Mississippi River which may lead to significant flooding.
A large and anomalous upper-level low will move slowly across northern Mexico over the next couple days. East of this low, a plume of deep tropical moisture will continue streaming northward into the southern plains and the lower/middle Mississippi valley. This moisture will interact with a couple frontal boundaries across the region to produce widespread showers and thunderstorms. Due to the very slow movement of the upper-level low, showers and thunderstorms will continue to affect many of the same areas through Friday. Heavy rain falling over the same areas repeatedly will lead to the threat of flash flooding for some areas.
Additionally, the Storm Prediction Center is forecasting a slight risk of severe thunderstorms today across portions of the western Gulf Coast states. Farther north, rain showers across the Midwest and Great Lakes
today will advance east into the Ohio valley and Northeast on Thursday ahead of a cold front. Snow and sleet may fall across northern New England Thursday evening into Friday morning.
The weather pattern will also remain active for the West Coast through the end of the work week. Rain and mountain snows will affect the Northwest, northern California, and portions of the Inter-mountain region today as a warm front approaches ahead of a deep Pacific Ocean low pressure system.
Precipitation will pick up in intensity by Wednesday night into early Thursday as the cold front moves onshore. Snow levels will gradually increase as the system approaches, with snow confined to the higher
elevations of the Cascades by Thursday morning. This cold front will move into the Inter-mountain region by late Thursday, with rain and high elevation snows. Another Pacific frontal system will approach the West Coast Thursday night into early Friday, spreading another round of rain and mountain snows into the region. This system will track a little farther south than the previous one, with rain spreading into central
California and snow for portions of the Sierras.