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    Day 2 Outlook >
Feb 21, 2018 0600 UTC Day 1 Convective Outlook
Click to see valid 1Z - 12Z Day 1 Convective Outlook
Updated: Wed Feb 21 05:44:18 UTC 2018 (Print Version | 20180221 1200Z Day 1 shapefile | 20180221 1200Z Day 1 KML)
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 Forecast Discussion
   SPC AC 210544

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1144 PM CST Tue Feb 20 2018

   Valid 211200Z - 221200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM EASTERN
   TEXAS TO WESTERN MISSISSIPPI...

   ...SUMMARY...
   Thunderstorms are forecast from Texas to the Ohio Valley and
   Appalachians today into tonight, and a few of these storms may be
   strong to severe from the Sabine Valley to western Mississippi.
   Locally damaging winds and perhaps a tornado will be the main
   threats.

   ...Synopsis...
   The mid/upper pattern across the country will witness little
   large-scale change today. An impressive ridge will persist
   along/offshore the East Coast, while a western-US trough is
   reinforced by a jet maximum advancing southward along the California
   coast. Between the two, a broad corridor of strong southwesterly
   flow will persist from the southern Plains to the Great Lakes
   region. Meanwhile, surface high pressure will build over the
   northern Plains and upper Midwest, helping push a cold front
   southeast across southern/eastern Texas, the lower Mississippi
   Valley, and the Ohio Valley.

   ...Eastern Texas to Mississippi...
   Aided by widespread precipitation across the cool sector, a cold
   front is forecast to continue progressing towards the Texas coast
   and Sabine Valley through the early morning hours. However, as one
   or more weak shortwave impulses lifts northeast within the
   sub-tropical channel, a slowly amplifying southerly low-level jet
   should slow the southeastern advance of the combined front/outflow
   boundary over northern Louisiana. Furthermore, broad forcing for
   ascent may induce a weak surface low along this baroclinic zone
   during the afternoon and evening hours. Within the warm sector
   along/ahead of this frontal wave, surface dew points in the upper
   60s are expected to foster upwards of 500-1000 J/kg of MLCAPE,
   despite modest 700-500mb lapse rates. 

   Thunderstorms should organize along the front, with some enhancement
   in eastward propagation supported by any mergers from development
   within moist/confluent flow in the open warm sector. A few small,
   northeastward-advancing bowing segments may organize through the
   afternoon and evening, owing to primarily uni-directional southerly
   flow within the cloud-bearing layer. These cells will chiefly pose a
   localized damaging wind threat. However, subtle backing of surface
   flow near the front, combined with any northwest-southeast oriented
   bands, may support a tornado or two as well.

   ..Picca/Leitman.. 02/21/2018

   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z

        
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Page last modified: February 21, 2018
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