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    Day 2 Outlook >
Feb 20, 2018 1630 UTC Day 1 Convective Outlook
Updated: Tue Feb 20 16:17:21 UTC 2018 (Print Version | 20180220 1630Z Day 1 shapefile | 20180220 1630Z Day 1 KML)
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 Forecast Discussion
   SPC AC 201617

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1017 AM CST Tue Feb 20 2018

   Valid 201630Z - 211200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PARTS OF
   TEXAS INTO THE OZARKS...

   ...SUMMARY...
   Thunderstorms are expected across a broad part of the south-central
   U.S. into the Midwest, with the possibility of a few strong to
   locally severe storms through this evening from central Texas into
   parts of the Ozarks.

   ...Synopsis...
   A broad long wave trough is expected to persist over the western
   CONUS as an initial short wave trough near the four-corners areas
   lifts northeastward and deamplifies, and an upstream short wave
   trough off the Pacific NW coast moves southward toward the central
   California coast.  A strong cold front at the surface, currently
   located from extreme northwest Illinois into southwest Missouri,
   southwest Oklahoma into east central New Mexico, will continue
   moving southeastward into across the middle Mississippi Valley and
   the southern Plains.

   ...Southern Plains into the Ozarks...
   Multiple bands of convection are occurring within a broad region of
   moist southwest flow aloft from central Texas into the Midwest.  12Z
   regional soundings ahead of the cold front indicate generally weak
   deep layer lapse rates but FWD and OUN soundings exhibited layers of
   7-8 C/km lapse rates that are enhancing zones of buoyancy. 
   Thunderstorms have organized into several lines over north central
   Texas with radar depicting occasional bow echo signatures moving
   toward the northeast.  Latest VAD wind profiles show winds of 40-50
   kt in the lowest 1 km AGL suggesting potential for a few strong to
   locally severe wind gusts to reach the surface as convective
   downdrafts transfer the strong horizontal momentum downward.  In
   addition, marginal hail may occur with a few of the stronger
   updrafts, especially over parts of Texas, where steeper lapse rates
   are likely to persist.

   Although mid-level height changes over the southern Plains will
   remain neutral or are slightly positive as the long wave trough
   remains over the west, water vapor imagery indicates additional
   perturbations will move northeast from the Big Bend region of Texas
   over the southern Plains toward the Ozarks.  This suggests potential
   for additional convection to develop this afternoon.  12Z HREF
   guidance and latest HRRR hourly runs are consistent with this
   scenario, showing several strong organized convective bands/clusters
   spreading from Texas into Arkansas later this afternoon and evening.
   CAM simulated reflectivity forecasts indicate transient QLCS
   structures with embedded bow echoes, suggesting a continued
   potential for a few strong to locally severe wind gusts in
   association with stronger storms through the evening hours.

   ..Weiss/Smith.. 02/20/2018

   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z

        
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Page last modified: February 20, 2018
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