Severe Storm Outlook Narrative (AC)
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ACUS03 KWNS 170559
SWODY3
SPC AC 170559

Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
1259 AM CDT Thu Aug 17 2017

Valid 191200Z - 201200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
CENTRAL HIGH PLAINS...

...SUMMARY...
Isolated severe thunderstorms are possible across the central High
Plains Saturday.

...Discussion...

Pronounced short-wave trough will advance across the Midwest into
the Northeast during the day3 period and a much weaker flow regime
is expected across the western/central contiguous US in its wake.
Seasonally strong northwesterly flow is expected across portions of
the mid MS Valley but it`s not clear how much convection will occur
post short wave or the degree of disruption late day2 convection
will have on this air mass. For these reasons the highest
predictability region Saturday will be across the central High
Plains where steep lapse rates and modest buoyancy will exist.

...Central High Plains...

Latest model guidance suggests a weak short-wave trough will dig
southeast across the northern Rockies toward the central High Plains
Saturday and this should sharpen the lee trough across the
northern/central High Plains region during the day. As a result,
higher PW air mass is expected to advance northward across western
KS into western NE where strong boundary-layer heating is expected
to weaken/remove CIN by 21z-22z time frame. Forecast soundings near
the lee trough suggest adequate deep-layer shear for a few robust
storms given the steep lapse rates and moistening profiles. If the
aforementioned short-wave trough times correctly into this region it
appears a few strong/severe thunderstorms could evolve across the
central High Plains. Hail/wind are the primary threats.

..Darrow.. 08/17/2017

$$


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