Valid 081200Z – 091200Z
…THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS CENTERED OVER
THE CENTRAL HIGH PLAINS REGION…
Isolated severe thunderstorms with strong/gusty winds and hail will
be possible across parts of the central Rockies and adjacent High
Plains Sunday afternoon and evening.
Cyclonic flow aloft will diminish over the northeastern U.S., as a
low shifts northeastward across the Canadian Maritimes. In the
West, a lead trough is forecast to shift east across the
Intermountain West, eventually reaching the high Plains, ahead of a
larger trough/low expected to move gradually onshore over the West
Coast. In between the western and northeastern troughing,
low-amplitude ridging will cross the central U.S. through the
At the surface, a weak baroclinic zone will lie east to west across
Missouri and Kansas, and then northwestward along the high Plains.
As the upper system advances across the Rockies, a weak/elongated
frontal low is forecast to gradually develop, centered over the
northeastern Wyoming vicinity.
…Central High Plains vicinity…
As the upper trough crosses the West, showers and thunderstorms are
forecast to increase in coverage through the day across a broad
portion of the Intermountain region. As increasing ascent begins
reaching the high Plains during the afternoon, where low-level
southeasterly flow is expected to maintain a slightly more moist
low-level airmass, the more favorable instability will support an
increase in storm coverage and intensity.
The approach of the upper system will also bring a modest increase
in flow aloft, likely supporting a progression of convection off the
higher terrain and across the central high Plains — possibly
evolving into a semi-organized band or bands into the evening hours.
This evolution will correspond with some potential for gusty/locally
damaging winds, and possibly marginal hail through the evening