Developing low pressure will move along the Eastern Seaboard today, leading to widespread precipitation. Rain is expected across the Southeast, Mid-Atlantic, and coastal Northeast today, while the interior Northeast will be cold enough to get snow. Rainfall totals will be around an inch in coastal New England, snowfall totals could be high in northern New England, with 6 to 8 inches.
There is a growing signal supporting ample leading wave/frontal genesis and deep moisture return to would fuel heavy rain/convection expansion northward across the east-central then eastern U.S. Moisture feeding back into a sharpening baroclinic zone meanwhile presents an organized snow threat through the Appalachians/Ohio Valley, with ample lake effect enhancement lee of the Great Lakes. Significant early season snows are possible.
Very cold weather is expected to be in place across the Great Plains through at least the end of the week with high temperature departures from normal ranging between 10 to 25 degrees below average from the Canadian border to the Rio Grande. Upper level disturbance will approach the Central Plains tonight, increasing snowfall coverage with locally moderate intensities into the central High Plains. 2-4 inches, locally higher, can be expected by Thursday afternoon.
Monday night/Tuesday is the focus for the next system. This one a deepening low tracking from the southern Plains to the Great Lakes will bring another round of rain showers to everyone, potentially some embedded thunder, and plenty of post-frontal wind. The biggest change/trend has been for the axis of heavier rainfall to shift southward. This has lowered QPF amounts to around a half inch to three quarters of an inch.
Weak low pressure will track off of the New Jersey coast today, and east of Montauk tonight. This will bring rain to the area along with an easterly breeze. Temperatures will be close to or below average due to the rain. The Tri-State Region will then warm into the 60s on Tuesday as winds become southerly. Another cold frontal passage however will produce additional rain during the day, with a few embedded thunderstorms also possible.
Severe storms are expected along and ahead of a cold front stretching from the Lower Mississippi Valley into the Ohio Valley. Potentially significant severe weather threat capable of damaging winds, strong tornadoes, and large hail is expected overnight into Tuesday from northern Mississippi across Tennessee and into central Kentucky. A frontal system over the western U.S. is forecast to drop southeast into the central Plains later today.
On Thursday, the flash flood threat is greatest along the central Gulf Coast states, as well as into portions of the Ohio Valley and lower Great Lakes, shifting eastward into the Northeast on Friday as this portion of the front begins lifting northward as a warm front. Across the central Gulf Coast states, severe weather with the main threats being tornadoes and damaging winds, will also be possible and SPC has this region within a slight risk on Thursday.
...Widespread heavy rainfall expected near a cold front from the southern Plains/Gulf Coast northward to the Ohio Valley and lower Great Lakes through Thursday night... Hazards associated with this frontal system will be heavy rain. Two to four inches of rain is forecast from southeastern Texas into and along the central Gulf Coast through Thursday, with similar totals (locally higher) from the Mid-Mississippi Valley into the Ohio Valley through early Thursday night.