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    Day 2 Outlook >
Sep 19, 2018 0600 UTC Day 1 Convective Outlook
Updated: Wed Sep 19 05:44:09 UTC 2018 (Print Version | 20180919 1200Z Day 1 shapefile | 20180919 1200Z Day 1 KML)
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 Forecast Discussion
   SPC AC 190544

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1244 AM CDT Wed Sep 19 2018

   Valid 191200Z - 201200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER A PORTION
   OF THE CENTRAL THROUGH NORTHERN PLAINS AND UPPER MISSISSIPPI
   VALLEY...

   ...SUMMARY...
   A few severe storms with a threat for mainly hail and gusty winds
   are possible across parts of the northern Plains and upper
   Mississippi Valley today.

   ...Synopsis...

   A shortwave trough moving onto the West Coast will advance through
   the Rockies and Great Basin regions this period, reaching the
   central through northern High Plains late tonight. Downstream from
   this feature an upper ridge will persist from the southeast states
   to the central through northern Plains and MS Valley regions. A
   front will extend from southern NE eastward through southern IA
   early in the day. Western extent of this boundary will begin to
   accelerate south as a cold front later today in wake of a vorticity
   maximum moving along the northern periphery of the upper ridge.

   ...Central and northern Plains through upper Mississippi Valley
   region...

   Forcing for ascent attending a low-amplitude shortwave trough is
   already beginning to foster the development of storms over the High
   Plains of western NE through western SD. This zone of ascent will
   continue east, resulting in the expansion of elevated storms through
   the northern Plains and upper MS Valley through the morning. A
   marginal risk for mainly hail will exist with the early storms, but
   some of the activity could also produce gusty winds as storm congeal
   into clusters or line segments. A temporary decrease in storm
   coverage may occur during the day, but increasing isentropic ascent
   associated with a strengthening low-level jet should foster
   redevelopment of mostly elevated storms north of the front during
   the evening. Large hail should be the main threat given 7-7.5 C/km
   mid-level lapse rates, moderate instability and 40-50 kt effective
   bulk shear, but storms developing closer to the surface front may
   also pose some risk for locally strong wind gusts. Due to limited
   forcing in warm sector and presence of a capping inversion, it
   appears most storms will remain elevated well north of the front
   which should limit primary threat to hail, some of which could reach
   severe levels. This in conjunction with expected messy storm modes
   lowers overall confidence in a more robust severe threat, but area
   will continue to be monitored for a slight risk upgrade in later
   outlooks.

   ..Dial/Wendt.. 09/19/2018

   CLICK TO GET WUUS01 PTSDY1 PRODUCT

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

        
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Page last modified: September 19, 2018
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