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    Day 2 Outlook >
Jun 28, 2017 0100 UTC Day 1 Convective Outlook
Updated: Wed Jun 28 00:54:13 UTC 2017 (Print Version | 20170628 0100Z Day 1 shapefile | 20170628 0100Z Day 1 KML)
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 Forecast Discussion
   SPC AC 280054

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0754 PM CDT Tue Jun 27 2017

   Valid 280100Z - 281200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
   CENTRAL AND EASTERN NEBRASKA INTO FAR SOUTHERN SOUTH DAKOTA...

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OUTSIDE OF THE
   ENHANCED RISK ACROSS PARTS OF THE CENTRAL AND NORTHERN PLAINS...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OUTSIDE OF THE
   SLIGHT RISK AREA ACROSS PARTS OF THE NORTH-CENTRAL STATES...

   ...SUMMARY...
   Severe thunderstorms capable of large hail and damaging winds are
   expected over much of Nebraska and South Dakota this evening, with
   the potential for hailstones greater than 2 inches in diameter and
   damaging wind gusts in excess of 65 knots.

   ...Central and Northern Plains/Mid Missouri Valley...
   The latest water vapor imagery shows a shortwave ridge over eastern
   parts of the Dakotas extending southward into the mid Missouri
   Valley with a shortwave trough in the northern Rockies. At the
   surface a cold front is moving eastward across the western Dakotas
   and far western Nebraska. Ahead of the front, a corridor of
   maximized low-level moisture is located across the central and
   northern Plains. The RAP is analyzing moderate to strong instability
   along this corridor with MLCAPE in the 2000 to 4000 J/kg range.
   Thunderstorms are ongoing along the western edge of the stronger
   instability in southwestern South Dakota and west-central Nebraska.
   This activity should continue to grow upscale, moving eastward into
   higher quality moisture and stronger instability. As the shortwave
   trough moves into the region from the west and low-level flow
   strengthens across the Plains, MCS development will be possible. 

   In addition to moderate instability, the WSR-88D VWP at North
   Platte, NE shows a supercell wind profile with strong directional
   shear in the lowest 2 km AGL and 30 to 35 kt of westerly flow in the
   mid-levels. The 00Z sounding from North Platte also shows a very
   steep mid-level lapse rate exceeding 8.0 C/km. This environment
   should support supercells with large hail and the more dominant
   storms may be capable of producing hailstones greater than 2 inches
   in diameter. Supercells will be most likely over the next 2 to 3
   hours but a transition to linear mode is expected to take place
   during the mid to late evening. This should result in an increasing
   wind damage threat especially if a linear MCS can organize across
   the region. Due to the strong instabililty and steep low-level lapse
   rates, any persistent bowing line of storms may be able to produce
   damaging wind gusts exceeding 65 knots. The severe threat should
   eventually reach the mid Missouri Valley by during the late evening
   and overnight period. See MCD 1165 for more information on the South
   Dakota part of the Enhanced risk area.

   Isolated severe storms will be possible further to the south across
   western Kansas and the Oklahoma Panhandle where a narrow corridor of
   moderate instability is analyzed by the RAP. Farther west and north
   across parts of the northern High Plains and North Dakota,
   convective coverage should remain more isolated but a marginal
   severe threat will be possible due to an adequate combination of
   instability and deep-layer shear.

   ..Broyles.. 06/28/2017

   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0600Z

        
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Page last modified: June 28, 2017
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