SPC AC 291630

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1130 AM CDT Wed Jul 29 2020

   Valid 291630Z - 301200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS MUCH OF THE
   WESTERN KANSAS VICINITY...

   ...SUMMARY...
   Scattered storms -- capable of producing locally severe wind gusts
   and hail -- will be possible during the late afternoon and evening
   across much of western Kansas.

   ...Synopsis...
   An weakening upper low near James Bay is progged to gradually open
   into a positively tilted trough over eastern Canada, while the
   associated/surrounding belt of cyclonic flow aloft moves slowly
   eastward across the northeastern quarter of the country.  Meanwhile,
   weak short-wave troughing shifting southeastward out of the Rockies
   and across the Plains will phase weakly with the northeastern U.S.
   troughing, with the evolving cyclonic flow field  expanding to
   include most of the eastern 2/3 of the country by the end of the
   period.  In the West, upper ridging will prevail, though a
   fast-moving cyclonic disturbance over the eastern Pacific will
   approach the northern California coast late in the period.

   At the surface, an east-northeast to west-southwest cool front will
   make slow southward progress across New England and the Lower Great
   Lakes region, while the western extension of this boundary lingers
   across the Iowa/Nebraska area through the period.  High pressure
   will prevail over the southeastern U.S., and over the Rockies.

   ...Northern High Plains southeastward across Kansas and vicinity...
   Weak/complex short-wave troughing aloft will continue to contribute
   broad large-scale ascent across the central Plains vicinity today,
   with the aforementioned cold front, along with convective outflow
   across the northeastern Kansas vicinity acting as foci for continued
   convective development.  However, more substantial storms are
   expected to develop near lee troughing/low pressure extending from
   southwestern South Dakota southward to eastern Colorado/western
   Kansas.  Here, strong afternoon heating will support
   continued/moderate destabilization, and a subsequent, north-south
   zone of storm development from near the Black Hills to far eastern
   Colorado/western Kansas by mid afternoon.

   A belt of enhanced west-northwesterly mid-level flow over the
   Colorado vicinity will continue to spread eastward across the
   central High Plains into Kansas, providing favorable deep-layer bulk
   shear to support organized/rotating storms.  Initial risk for both
   large hail and locally damaging winds may transition more toward
   wind risk with time into this evening, with hints that storms may
   congeal into one or more semi-linear/southeastward-moving clusters. 
   Storms will likely continue overnight, though severe risk should
   begin to wane by late evening.

   ...Lower Great Lakes region...
   A belt of moderate westerly/cyclonic flow aloft will persist across
   the region today, as eastern Canada upper troughing moves very
   slowly eastward.  A weak surface cool front extending from the
   Adirondacks west-southwestward to southern Lower Michigan will
   provide a focus for convective development, as the airmass continues
   to modestly destabilize through the afternoon.  Given the
   aforementioned/enhanced flow aloft, a couple of
   organized/fast-moving storms/storm clusters will be possible, with
   attendant risk for a locally damaging wind gust or two.  Risk will
   diminish quickly through early evening, with the onset of diurnal
   cooling.

   ..Goss/Lyons.. 07/29/2020

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