SPC Day 4-8 Discussion:
"The beginning of the period will see an upper trough over the
eastern states and an upper ridge over the West. The upper ridge
will weaken as it slides east over the Plains on Day 5/Sat, with a
lower-amplitude pattern emerging east of the Rockies through Day
6/Sun. During the latter half of the period, an upper trough is
forecast to develop over the western U.S. Strong surface high
pressure over the Plains on Day 4/Fri will shift east through the
period, and another frontal intrusion into the Gulf of Mexico will
result in a generally dry/stable airmass for much of the Day 4-8
period. As the western upper trough develops late in the period,
surface lee troughing will promote southerly low-level flow over the
southern Plains and some Gulf moisture return is expected. As this
occurs, thunderstorm potential may increase across parts of the
southern Plains around Days 7-8/Mon-Tue. Modest deep-layer flow over
the region, and the upper trough remaining well west, will likely
limit severe potential until perhaps just beyond Day 8/Tue."