Severe weather moves from the Plains towards the Mid-Atlantic

Severe weather is a risk over the next couple of days from the Plains and Gulf Coast regions into the Appalachians towards the Mid-Atlantic.  While there is a low risk for tornadoes, there are significant risks for widespread damaging winds and  large hail.

A stationary front has been the focus for strong to severe thunderstorms over the Plains in recent days bringing over 900 reports of severe hail and wind from Texas to Wisconsin.  This front is interacting with a strong, fast moving cold front that will create the lift needed for a large area of showers and thunderstorms.  Some of these storms could be intense this morning as remnants of a Mesoscale convective system died out overnight across the Plains persists.  The severe weather moves on into the Appalachians by Sunday, and on to the Mid-Atlantic up into New England for Monday.

Saturday

The cold front, along with a strengthening low pressure system, will continue to progress southeastward from Central Iowa into Central Kansas.  The air ahead of this front remains warm and unstable with plenty of moisture.

Storms are likely to begin over Iowa and northern Kansas before spreading East from Michigan down into Missouri.  These thunderstorms are expected to form into linear squall lines over time due to weak low level shear yielding outflow dominant storms.    Any storms should begin to weaken after nightfall as they move east, where lapse rates will be lower.

Sunday

Scattered thunderstorms, with a primary risk of damaging winds, are expected from the Great Lakes into Northeast Texas.  The low pressure from Saturday will move from the Great Lakes into Canada but the cold front will remain across the Ohio Valley into the Southern Plains.

From the Great Lakes down through Tennessee, early remnants from overnight storms should clear with a moisture rich warm air-mass in place to meet the weakening cold front.  The ongoing wind regime should allow for strong multi-cluster cells to form.  Hail may also fall but will only be locally severe.

Further south, storms will be more isolated from the Texoma region into Arkansas.  Lift in this region will be weaker but the cold front will be a focus point for thunderstorms due to an elevated mixed layer and moist low level conditions.  These will form a very unstable boundary layer that could see the convective available potential energy (CAPE) approach 4000 Joules per kilogram.

In Mississippi and Alabama, scattered thunderstorms will develop during the daytime heating period.  Seasonably warm and moist air will become more unstable under conditions that have very little convective inhibition.  Strong to severe cells that do form will likely have marginally severe hail and localized damaging winds.

All southern storms should begin to weaken during the evening hours as daytime heating fades.

Starting off the work week, the Northeast and Mid-Atlantic are looking at pending severe weather as the cold front pushes east into more warm moist air Monday afternoon into the overnight hours effecting all the major metropolitan areas.

Rob