Heavy rain and flooding possible Thursday.

Scattered thunderstorms will develop across a large portion of the US Thursday. A few storms may produce gusty winds across the central/northern High Plains and from Oklahoma to southern New England.

High-PW plume will be gradually shunted southeast across the contiguous US during the day2 period as a frontal zone progresses to a position from Lake ON, southwest across IN into northern OK by 18z. This high PW plume will be characterized by poor lapse rates with embedded left over convective MCVs. Each of these features will be difficult to predict with any certainty beyond a few hours and 12z model guidance is not particularly useful identifying any notable feature that could aid organized strong convection. Even so, short-wave troughing will shift across ON into QC with the southern extent of this feature expected to extend to a latitude of southern New England. Deep-layer shear will be notably stronger across the northeastern US ahead of this feature but forecast instability appears inadequate for more than marginal severe at this time. Gusty winds are the primary threat with convection across this region.

Farther southwest from the TN Valley into the southern Plains, strong boundary-layer heating will be focused along this corridor with the steepest lapse rates occurring over the southern Plains where surface temperatures should soar to near 100F. With PW values expected to be near 2″ across this region a few damaging downbursts seem possible.


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