While the heat persists in the southeast, there is a slight threat for severe weather on 4 July 2018. The slight severe weather threat contains central and northeast Nebraska, northwestern Iowa, southern and eastern Minnesota, the southeast corner of South Dakota and northwestern Wisconsin. Main threats for this event include damaging winds, and large hail; however, a tornado cannot be ruled out. There is a mesoscale convective system that has a history of producing hurricane-force wind gusts. The area has been under a severe thunderstorm watch for the overnight hours but as the system moved east, the watch was discontinued. As it moves eastward, the system moves into a less favorable environment. For the remainder of the day, widely scattered thunderstorms are expected to develop into the afternoon. There is risk for general thunderstorms for the central, southeast and east coast of the United States which means storms are not expected to be severe (although it cannot be ruled out).
These storms could put a damper on Independence Day celebrations especially during the evening hours. People who gather outdoors to watch fireworks and parades need to stay weather alert. In the event a thunderstorm threatens your area, seek shelter immediately. Remember, “when thunder roars, go indoors.”
You can read the entire synopsis from the NOAA Storm Prediction Center below:
A long-lived MCS that produced hurricane-force measured gusts around MBG overnight continues to weaken gradually as it moves into somewhat less-favorable environment across northern MN. Still, a severe gust or two remains possible with near-leading-edge convection forced by the cold pool. Widely scattered to scattered thunderstorms, in discontinuous nodes or clusters, are expected to develop through this afternoon near the front and prefrontal/outflow boundaries, from the Upper MS Valley to central/southwestern NE and northeastern CO. Damaging gusts and sporadic large hail are expected from the most intense activity. In addition to afternoon development, this scenario may include regeneration of thunderstorms later this morning over portions of MN along the outflow boundary from ongoing activity, as it impinges on a destabilizing boundary layer. Regardless, rich low-level moisture from central NE northeastward will combine with diabatic surface heating and steep midlevel lapse rates to boost pre-convective/warm-sector MLCAPE into the 3500-4500 J/kg range. Although large-scale ascent aloft should become more displaced from the region through the day, given the track of the aforementioned shortwave trough, that heating along with lift along the boundaries will support pockets of convective development and fairly rapid intensification in that large-buoyancy setting. Initial multicell and messy supercell modes are possible, with upscale clustering anticipated late afternoon into evening. Given the geometry of the mid/upper-level pattern and related northern-stream height gradient, flow aloft and deep shear should decrease with southward extent. Veering wind profiles with height are expected to aid in convective organization, even over southern parts of the outlook area where absolute flow in midlevels will be modest in closer proximity to the axis of the anticyclone. Additionally, an MCV -- now evident in radar composites over northeastern NE -- also may augment deep-layer lift on the mesobeta scale over part of the upper MS Valley region this afternoon.
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ⓒ 2018 Meteorologist Brandie Cantrell