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Mesoscale Discussion 1520
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   Mesoscale Discussion 1520
   NWS Storm Prediction Center Norman OK
   0627 PM CDT Mon Aug 17 2020

   Areas affected...Northeast Oregon...far southeast Washington...and
   western Idaho

   Concerning...Severe Thunderstorm Watch 446...

   Valid 172327Z - 180100Z

   The severe weather threat for Severe Thunderstorm Watch 446
   continues.

   SUMMARY...The severe weather threat continues across severe
   thunderstorm watch 446. Severe wind gusts are the primary hazard.

   DISCUSSION...Several severe wind gusts were reported earlier this
   afternoon in Harney county, but no severe wind has been measured
   since. However, the loosely organized cluster of storms in eastern
   Oregon is moving into a more favorable airmass in northeast Oregon
   in the next 1 to 2 hours. Temperatures ahead of this activity are
   around 100F with dewpoints around 50F. This is yielding MLCAPE
   around 250 J/kg with mid-level moisture supporting MUCAPE above 500
   J/kg. Therefore, these storms are likely a combination of surface
   based and elevated at this time. Instability is the primary limiting
   factor at this time, but if storms can continue to grow upscale and
   organize, severe winds are likely given the moderate to strong lower
   tropospheric flow and very steep low-level lapse rates per SPC
   mesoanalysis. 

   While this portion of northeast Oregon may pose the greatest severe
   threat over the next few hours, an additional, more isolated severe
   threat will also persist farther west. A multicell cluster of storms
   has formed near Madras, OR in an area with poor radar coverage,
   however, lightning and satellite trends suggest a strong-well
   organized updraft. Low to mid-level moisture is higher in this area
   yielding MLCAPE around 500 J/kg and MUCAPE around 1000 J/kg, and
   mid-level flow is somewhat stronger. Storm coverage may remain more
   isolated in this area, but any sustained updrafts may pose a threat
   for severe winds.

   ..Bentley.. 08/17/2020

   ...Please see www.spc.noaa.gov for graphic product...

   ATTN...WFO...MSO...BOI...OTX...PDT...

   LAT...LON   44412157 45482095 46061945 46411764 46641611 46591540
               46101519 45261555 44541618 43801654 43431692 43451734
               43621775 43961826 44071879 44141937 44412157 

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Page last modified: August 18, 2020
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