Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0355 AM CDT Sun Jun 28 2020 Valid 011200Z - 061200Z ...DISCUSSION... Medium-range models remain in generally good agreement with respect to the large-scale pattern over the U.S. through the medium-range period. Day 4 (Wednesday 7-1), a negatively tilted short-wave trough will continue advancing northeastward across the northern Plains, likely shifting into the Canadian Prairie by early in the Day 5 period. As this occurs, ample ascent will likely aid in weakening of the cap near the weak/advancing surface front to allow scattered thunderstorm development to occur. Given moderately strong, meridional flow aloft, a few organized/severe storms are expected, and thus a 15% risk area will be included across this region. In the wake of this feature, stagnation of the upper pattern is expected, with a trough remaining near/just off the Pacific Northwest Coast, and troughing/cyclonic flow lingering in the East. Between the two features broad/relatively flat ridging is expected across much of the country. On the northern fringe of the evolving/broad ridge -- in the vicinity of the U.S./Canada border -- a belt of fast/weakly anticyclonic flow is expected to evolve. Weak disturbances moving through this westerly flow will likely result in episodic severe convective events, but timing/location of these individual events remains highly uncertain. Therefore, no risk areas will be introduced at this time in the Day 5-8 portion of the period.Read more
from SPC Forecast Products http://www.spc.noaa.gov/products/exper/day4-8/
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