Lake effect snow continues downwind of Lake Ontario, before adeveloping low pressure system spreads snowfall east into northern NewEngland tomorrow...Light to moderate snow enters the northern Plains midweek and pushesinto the Upper Midwest on Thursday.Shower and thunderstorm chances return to the Southern Plains andwestern Gulf Coast.Cool and breezy weather remains entrenched across the eastern half of thecountry as a secondary cold front over the Midwest reinforces the chillyairmass overhead. One consequence of the renewed northwest flow crossingover relatively warm lake waters will be additional lake effect snowshowers focused downwind of Lake Ontario in New York, which will befurther enhanced as a low pressure system crosses from southern Ontario,Canada towards Maine through early Thursday. The forecast continues tohighlight Medium probabilities (40-70%) for at least 6 inches of snowthrough Thursday across portions of the Interior Northeast and NewEngland. Gusty winds and below average temperatures are forecast in thesystem's wake, with highs only expected to reach into the 30s and 40sthroughout the Great Lakes, Ohio Valley, and Northeast by the end of thework week.Over the nation's Heartland, snow potential will return to the NorthernPlains and Rockies tomorrow morning as a stalling cold front interactswith favorable jet stream dynamics. Northwest Montana maintains thehighest chances of seeing over 4 inches of snowfall (80%), althoughportions of the Northern Plains and Midwest could locally exceed 4 inchesby Friday as a low pressure wave spins up along the aforementionedstationary front. Uncertainty remains on exactly where the heaviestsnowbands may set up, but residents should remain weather aware andprepare for potentially difficult travel across the Upper Midwest betweenThursday night and Friday morning.In the warm sector of the font, rain and thunderstorm chances return onWednesday as an upper low lingering over the Southwest finally ejectseastward. A few isolated thunderstorms could turn severe over westernOklahoma and the Texas Panhandle, as well as south-central Texas. ByThursday, heavy rain may develop along the Texas and Louisiana Gulf Coast,which could lead to isolated flooding concerns.As far as the temperature highlights for the short term time period,lingering frost concerns remain across portions of the Southeast throughtomorrow morning, although this cold snap is forecast to be short-lived astemperatures warm to near average by Thursday across the South. Meanwhile,above average temperatures are expected today across the central Plainsand Northwest. A few daily temperature records remain possible todayacross the northern Great Basin and Pacific Northwest as thermometerreadings soar into the 70s.