Day 4-8 Outlook
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0347 AM CDT Thu Jun 30 2022
Valid 031200Z - 081200Z
...DISCUSSION...
Medium-range guidance indicates little change to the amplified split
flow across the eastern Pacific into western North America through
early next week. Thereafter, into the middle to latter portion of
next week, it appears that the blocking high over the Canadian Yukon
and Northwest Territories may begin to weaken. As it does, the
persistent mid-level troughing near and offshore of the U.S. Pacific
coast may lose amplitude, with the most prominent embedded
perturbation (likely the remnants of a mid-level low) forecast to
accelerate northeastward just offshore of the Pacific Northwest
coast by early Friday. This probably will be accompanied by
substantive amplification of downstream mid-level ridging across and
just east of the northern U.S. and Canadian Rockies, while mid-level
subtropical ridging also becomes more prominent across the Colorado
Plateau and southern Rockies vicinity.
Prior to the pattern changes, it still appears that an increase of
boundary-layer moisture through much of the Missouri Valley, beneath
steep mid-level lapse rates associated with warm elevated
mixed-layer air emanating from the Rockies, may once again
contribute to a broad area of moderate to strong potential
instability. And at least one significant perturbation emanating
from the Pacific coast troughing, before migrating around the
northern periphery of the downstream ridging, may contribute to a
corridor of increasing severe weather potential across the northern
Intermountain region and northern Rockies, through areas
near/northeast of the middle into lower Missouri Valley. This is
where shear on the southern fringe of the westerlies, coupled with
the increasing instability, will promote a conditional risk for the
evolution of longer-lived organized convective systems with the
potential to produce strong surface gusts. However, the
predictability of these sub-synoptic features is low at this
extended range.
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