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Aug 19, 2017 0730 UTC Day 3 Severe Thunderstorm Outlook
Updated: Sat Aug 19 07:16:51 UTC 2017 (Print Version | 20170819 0730Z Day 3 shapefile | 20170819 0730Z Day 3 KML)
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 Forecast Discussion
   SPC AC 190716

   Day 3 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0216 AM CDT Sat Aug 19 2017

   Valid 211200Z - 221200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS MONDAY INTO
   MONDAY NIGHT ACROSS PARTS OF THE CENTRAL PLAINS AND LOWER/MIDDLE
   MISSOURI VALLEY INTO THE UPPER MIDWEST...

   ...SUMMARY...
   Strong thunderstorms may impact a corridor from the central Plains
   into the Upper Midwest Monday into Monday night, accompanied by at
   least some risk for severe weather.

   ...Synopsis...
   The stronger mid-latitude westerlies likely will remain confined to
   the northern tier of the U.S and southern Canada through this
   period.  However, models indicate that amplification commencing
   within this regime, across the northeastern Pacific into western
   Canada on Sunday, will continue and translate downstream, with
   significant upper troughing likely to evolve and dig across the
   central Canadian/U.S. border area by late Monday night.  This is
   expected to be accompanied by the southward advancement of a cold
   front into and through much of Upper Midwest, lower Missouri Valley
   and central Plains, and perhaps the initiation of cyclogenesis along
   the front across the Great Lakes region by 12Z Tuesday.

   ...North central Plains into the Upper Midwest...
   The possibility for considerable lower/mid tropospheric warm
   advection driven convection to be ongoing at 12Z Monday near/east of
   the middle Missouri Valley is one of a number of uncertainties
   concerning convective potential for this period.  Also, relatively
   cool mid-level air and stronger mid/upper flow appear likely to lag
   behind the surface front.  However, models suggest that seasonably
   moist low-level conditions may still contribute to moderate CAPE
   with daytime heating.  And a belt of 30-40 kt westerly lower/mid
   tropospheric flow may be sufficient to support organized convective
   development.

   Within an increasingly cyclonic regime aloft, to the south of the
   main short wave trough, models indicate a possible consolidation of
   forcing associated with one short wave perturbation emerging from
   the southwestern monsoonal regime, and a mid-latitude impulse
   digging southeast of the northern Rockies.  This seems to provide
   the most obvious support for an appreciable evolving cluster of
   thunderstorms.  However, this appears most likely to take place
   across and east of the middle to lower Missouri Valley well after
   dark, when boundary layer instability may be in the process of
   waning.

   While severe potential is evident for Monday into Monday night,
   mostly in the form of evolving storms clusters accompanied by a risk
   for potentially damaging wind gusts, this appears too conditional
   for anything greater that 5 percent severe probabilities at this
   time.

   ..Kerr.. 08/19/2017

   CLICK TO GET WUUS03 PTSDY3 PRODUCT

   NOTE: THE NEXT DAY 3 OUTLOOK IS SCHEDULED BY 0730Z

        
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Page last modified: August 19, 2017
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