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    Day 2 Outlook >
Feb 21, 2018 1630 UTC Day 1 Convective Outlook
Updated: Wed Feb 21 16:04:35 UTC 2018 (Print Version | 20180221 1630Z Day 1 shapefile | 20180221 1630Z Day 1 KML)
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 Forecast Discussion
   SPC AC 211604

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1004 AM CST Wed Feb 21 2018

   Valid 211630Z - 221200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS TODAY FROM EXTREME
   SOUTHEAST TX TO NORTHEAST LA...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS INTO EARLY
   TONIGHT FROM SOUTHEAST TX TO CENTRAL MS...

   ...SUMMARY...
   Thunderstorms will continue from Texas today to the Ohio Valley and
   Appalachians today into tonight, some of which will be associated
   with freezing or frozen precipitation across northwest Texas and
   Oklahoma.  A couple of tornadoes and isolated strong wind gusts will
   be possible with the storms across Louisiana and adjacent areas of
   southeast Texas and west central Mississippi.

   ...Lower MS Valley and southern Plains through tonight...
   A deep warm/moist conveyor belt is established from the western Gulf
   of Mexico into the lower MS Valley, along and immediately southeast
   of a slow-moving cold front.  The pattern will change little through
   tonight as the large-scale ridge persists over the southwest
   Atlantic and at least two shortwave troughs continue to dig
   southward/southeastward along the Pacific coast to maintain the mean
   western trough.  Within the warm conveyor belt, a maritime tropical
   air mass (boundary layer dewpoints near 70 F) will continue to
   spread northward across LA/MS today, with some surface heating
   possible along the southeast periphery of the ongoing warm sector
   convection.  The storms are likely to persist through the day in
   this moist and uncapped environment per regional 12z soundings,
   where deep-layer vertical shear will be sufficient for supercells
   within the larger storm clusters.  Given the rich low-level moisture
   and effective SRH in excess of 200 m2/s2, a couple of tornadoes will
   be possible, along with isolated strong wind gusts.

   Otherwise, a swath of elevated convection will continue above the
   shallow cold air mass across the southern Plains.  The boundary
   layer will be sufficiently cold for a mix of sleet and freezing rain
   with the elevated convection from northwest TX into southern OK
   today through early tonight.

   ..Thompson/Darrow.. 02/21/2018

   CLICK TO GET WUUS01 PTSDY1 PRODUCT

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

        
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Page last modified: February 21, 2018
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