...Heavy rain and snow will continue a threat for flooding from the Lower Great Lakes into the Ohio Valley...A large winter storm will affect locations from the Upper Midwest to the East Coast beginning tonight. A dome of high pressure currently in place across the Great Lakes region has set the stage for wintry precipitation with temperatures near or below freezing from the Mid-Mississippi Valley to the northern Mid-Atlantic region. As an upper level system lifts through the Great Plains tonight, significant amounts of moisture will spread north and east from the Gulf of Mexico. Meanwhile, snow will move from southwest to northeast into Ohio, changing to a wintry mix of sleet and freezing rain and eventually all rain for many. The time of changeover will occur from southwest to northeast and depend on exact location but will be delayed for locations near the central Appalachians where significant ice accumulations near 0.25 inches along with 4-8 inches of snow (locally higher) will be possible. Portions of the Ohio Valley where an additional 1-3 inches of rain, on top of already saturated ground, can be expected through Wednesday afternoon. Flood and flash flood watches are already in effect for many of these locations. Additional heavy rain is expected to begin for some of these same locations impacted by flooding Thursday night.
WXD Alert: Active Discussion, Tracking, Observations
Lake effect snow is common across the Great Lakes region during the late fall and winter. Lake Effect snow occurs when cold air, often originating from Canada, moves across the open waters of the Great Lakes. As the cold air passes over the unfrozen and relatively warm waters of the Great Lakes, warmth and moisture are transferred into the lowest portion of the atmosphere. The air rises, clouds form and grow into narrow band that produces 2 to 3 inches of snow per hour or more.
...Significant winter storm for the Mid-Atlantic region on Wednesday...A large winter storm will affect locations on East Coast beginning tonight. A dome of high pressure currently in place across the Great Lakes region has set the stage for wintry precipitation with temperatures near or below freezing to the northern Mid-Atlantic region. As an upper level system lifts through the Great Plains tonight, significant amounts of moisture will spread north and east from the Gulf of Mexico.
Several Pacific disturbances are set to move across eastern Utah and western Colorado through the rest of the work week and into the weekend. The first wave will continue through this morning with the northern and central mountains favored for the most accumulation. The second storm will arrive this late afternoon and continue through early Friday. An abundance of moisture associated with an atmospheric river (AR) event will result in widespread shower coverage with this system.
A developing winter storm will bring widespread moderate to heavy snow to much of the Northeast by Tuesday night and early Wednesday. The potential exists for 6 to 12 inches of snow from northern Wisconsin to northern Michigan, and even higher amounts across upstate New York and northern New England with 12 to 18 inches possible. A corridor of freezing rain is likely to the south of the heavy snow axis, extending from the central Appalachians to southern New England, and also across southern Michigan. Significant travel impacts are anticipated through Wednesday.
...A stronger upper trough rotating out of the broader western CONUS trough from the Great Basin will quickly lift into central plains and Upper MS Valley on Sunday. Deep QG forcing with this system will bring widespread light snow to the area. There are still some subtleties to figure out with variation in the models with the highest QPF, especially if precip is enhanced in narrow fgen bands.
An area of freezing rain is expected to move over Southwestern Ontario Wednesday morning. The freezing rain could persist for much of Wednesday before ending Wednesday evening or overnight. The Wednesday morning commute will likely be affected due to the potential for untreated surfaces to become icy Surfaces such as highways, roads, walkways and parking lots may become icy and slippery. Be prepared to adjust your driving with changing road conditions. Ice build-up may cause tree branches to break.
A system will form on the lee of the Rockies around February 3 and cut through the Great Lakes, perhaps making for a small risk for severe weather. However, it looks like the cold front will stall out within this region before another system forms off the Rockies as the longwave trough pushes east. By the time the final cold front pushes through, the areas south of where the cold front stalled out will have been under 150 hours, or almost 7 days of southerly winds.
...The beginning of a heavy rain/flooding pattern is setting up across the mid-Mississippi and Ohio Valleys... As the Pacific storm system mentioned above moves east Wednesday into Thursday, moisture from the Gulf of Mexico together with strong upper-level dynamics will begin to bring an increasing chance of rain for the mid-Mississippi and Ohio Valleys. Total rainfall through Thursday could range between 3 to 5 inches for portions of the Ohio Valley which may cause flooding