Valid 040100Z – 041200Z
…THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS TONIGHT ACROSS
PARTS OF THE NORTHERN PLAINS…
…SUMMARY…
Severe weather potential with isolated strong storms across the
western Dakotas is expected to diminish this evening, but additional
strong storms posing some risk for severe hail and wind are possible
near the North Dakota/Manitoba border area later tonight.
…01Z Outlook Update…
…Northern Plains…
Models indicate that surface cyclogenesis will proceed across
northern Manitoba tonight, as a vigorous mid-level short wave trough
progresses east-northeastward across the Canadian Prairies. As this
occurs, an associated cold front is forecast to advance
southeastward into the Montana/North Dakota international border
area.
Although stronger mid-level forcing for ascent is and will remain
confined to areas north of the international border, some
combination of low-level warm advection and locally enhanced
low-level convergence has supported a narrow corridor of widely
scattered strong to severe thunderstorm development. This has been
focused along a dryline across the northern High Plains, to the east
of the stronger surface heating within pre-frontal surface
troughing, where mid-level inhibition became relatively weak.
However, with the onset of diurnal boundary layer cooling, in the
presence of weak/weakening large-scale forcing for ascent, ongoing
convection seems likely to diminish by/during the 02-4Z time frame.
There is at least some signal in model output that thunderstorm
activity, on the southern flank of stronger mid-level forcing for
ascent across Manitoba, could develop southward into the North
Dakota/Manitoba border area overnight. If this occurs, it appears
that the environment may be at least marginally conducive to
convection capable of producing severe hail and strong surface
gusts.
..Kerr.. 08/04/2019
$$