A developing storm over eastern Colorado will track through the Midwest and into the Great Lakes late this week, spreading widespread rain from the Ohio Valley to the Northeast. Inland areas of northern New England may see moderate to heavy snow Friday into Saturday, with rain along the coast. A cold front will sweep through the central and eastern U.S. this weekend, bringing a sharp turn from well above normal temperatures to near or below normal by Monday. Out West, precipitation tapers off briefly before a stronger system approaches next weekend, potentially producing heavy rain and mountain snow from northern California to Washington, with a possible atmospheric river event developing.

Today: A marginal risk of severe thunderstorms exists today along coastal areas of central and southern California. A strong upper-level system moving inland will combine with a cold front to produce bands of heavy showers and a few thunderstorms. While instability will be limited, conditions may support a few stronger storms capable of producing locally damaging wind gusts. A brief tornado cannot be ruled out near the coast before the threat shifts southward and weakens by early evening. Later tonight into early Tuesday, another disturbance will bring colder air aloft into coastal southwest Oregon and northern California, allowing low-topped thunderstorms to develop with gusty winds possible, especially near the immediate coastline.

Tuesday: No organized severe weather is expected Tuesday into Tuesday night, but scattered thunderstorms are possible in a few regions. In California, storms may redevelop from coastal areas into the Central Valley, especially north and central portions of the state. Cooler air aloft and a strengthening upper-level system could allow a few storms to produce gusty winds and small hail, particularly near the San Francisco Bay area, though widespread severe weather is unlikely. Farther east, thunderstorms may develop late Tuesday into Tuesday night from the mid-Missouri Valley into the Upper Midwest as a weather disturbance moves through. Limited moisture should keep the risk for large hail or damaging winds relatively low.

Wednesday: No severe thunderstorms are expected across the U.S. Wednesday through Wednesday night, and overall storm chances remain low. A weakening weather disturbance moving through the Upper Midwest and Great Lakes may produce just enough lift and limited moisture to support a few thunderstorms with lightning into the lower Great Lakes during the day, but coverage should be isolated. Farther west, a developing upper-level system near the Pacific Coast may trigger new low pressure forming east of the Colorado Rockies and into the central Great Plains late Wednesday. However, better moisture from the Gulf of Mexico is forecast to remain focused farther south and east, limiting the potential for stronger storms during this period.

Thursday - Monday: A strengthening storm system over the central Great Plains is expected to deepen further as it tracks northeast toward the Great Lakes late Thursday. Forecast guidance shows increasing moisture returning northward ahead of the storm, with dew points rising into the upper 50s to lower 60s near the Mississippi and Ohio River confluence and spreading into the lower Ohio Valley. Although instability appears modest, it should be sufficient for severe thunderstorm development given strong wind shear and large-scale lift. A few supercells could form, capable of producing tornadoes, along with a growing line of storms bringing damaging wind gusts Thursday evening. The system should weaken Friday, and storm chances are expected to decrease further by late weekend as high pressure builds eastward.

National Weather Outlook sources: Weather Prediction Center & Storm Prediction Center