Thursday, April 6, 2017

SPC Apr 6, 2017 Day 4-8 Severe Weather Outlook

Day 4-8 Outlook
Day 4-8 Outlook Image
Day 4-8 Convective Outlook  
NWS Storm Prediction Center Norman OK
0355 AM CDT Thu Apr 06 2017

Valid 091200Z - 141200Z

...DISCUSSION...
Models suggest that a pair of speed maxima (on the order of 50-70 kt
at 500 mb), within somewhat consolidated mid/upper troughing, will
progress east northeast of the southern Rockies on Sunday.  This may
support further deepening of a low center within lee surface
troughing, across the mid Missouri Valley, maintaining fairly strong
southerly low-level flow across lower portions of the central Plains
into the lower/mid Missouri Valley.  Although low-level Gulf
moisture return within a narrow corridor to the east of the surface
trough may remain somewhat modest, it probably will improve at least
somewhat, beneath steepening mid-level lapse rates associated with
mid-level cold advection atop a plume of warm elevated mixed layer
air across the central Plains.  By late Sunday afternoon,
mixed-layer CAPE may exceed 1000 J/kg, and the environment may
become conducive to initiation of discrete supercells, before
convection consolidates and grows upscale into an evolving
convective system, in the presence of favorable large-scale forcing
aided by southerly 850 mb jet intensification to 40-50+ kt Sunday
evening.  This probably will be accompanied by at least the risk for
severe hail and potentially damaging wind gusts.  Other,
strong/severe storm development may be possible along the dryline,
southward across parts of Oklahoma into Texas, but coverage is still
expected to remain more sparse across these areas than areas to the
north.

The possible stabilizing influence of residual convection from
Sunday, and weakening of the surface low, result in uncertain severe
weather potential as the upper impulse tracks toward the Great Lakes
region on Monday.  Thereafter, the latest medium-range model output
suggests that the upper pattern may begin to amplify once again,
with troughing across parts of the eastern Pacific into the
Intermountain West, and across the Atlantic Seaboard into the
western Atlantic, with ridging from near the Rockies to the vicinity
of the Appalachians.  This seems likely to be accompanied by
generally low severe weather potential through the middle portions
of next week.

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