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    Day 2 Outlook >
Jun 27, 2017 1630 UTC Day 1 Convective Outlook
Updated: Tue Jun 27 16:41:19 UTC 2017 (Print Version | 20170627 1630Z Day 1 shapefile | 20170627 1630Z Day 1 KML)
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 Forecast Discussion
   SPC AC 271641

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1141 AM CDT Tue Jun 27 2017

   Valid 271630Z - 281200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
   OF NEBRASKA AND SOUTHERN SOUTH DAKOTA...

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE
   NORTH-CENTRAL PLAINS...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE
   NORTHERN ROCKIES/HIGH PLAINS TO THE UPPER MIDWEST...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
   NORTHEAST STATES/NEW ENGLAND...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE FL
   PENINSULA...

   ...SUMMARY...
   Severe thunderstorms capable of large hail, damaging winds and a
   tornado or two are expected over much of Nebraska and South Dakota
   late this afternoon and evening, with the possibility that a few
   gusts may exceed hurricane force. Other strong to severe
   thunderstorms will be possible across parts of the Northeast States
   as well as the Florida Peninsula.

   ...Central/northern High Plains to middle MO Valley...
   A shortwave trough and related mid/high-level speed max are readily
   evident across the eastern ID/southwest MT/western WY vicinity and
   adjacent Great Basin per water vapor imagery and 12Z upper-air
   analysis. This eastward-progressive shortwave trough will reach the
   Dakotas and middle MO valley by this evening amid a steadily
   strengthening belt of mid-level westerlies.

   An initial increase in widely scattered strong thunderstorm
   development should occur this afternoon across interior WY (and far
   southern MT), where modest moisture/buoyancy will support some
   potential for severe hail and severe-caliber wind gusts. As forcing
   for ascent spreads eastward, additional development should occur by
   late afternoon in vicinity of the north/south-oriented lee trough,
   particularly across eastern WY/NE Panhandle and Black Hills
   vicinity. Large hail and damaging gusts will be possible for the
   first few hours, although very steep lapse rates and a relatively
   well-mixed environment should result in an upscale-growing and
   eastward-accelerating complex primarily across NE this evening. As
   mentioned in the prior outlook discussion, localized hurricane-force
   thunderstorm gusts are possible from the most intense surges of
   convection this evening.

   ...Northeast States/New England...
   Aided by a northeast-moving shortwave trough, scattered low-topped
   thunderstorms will continue to increase and spread
   east/northeastward across the region this afternoon. Relatively
   steep lapse rates, accentuated by cool mid-level temperatures (near
   -20C at 500 mb) will support stronger low-topped storms capable of
   hail, with a few low-topped supercells possible across southern New
   England where deep-layer shear will be somewhat stronger. For
   additional short-term information, see Mesoscale Discussion 1160.
   Convection should weaken as it moves eastward over either land-based
   evening diabatic cooling and/or the Atlantic marine layer.

   ...Florida...
   Ample insolation and a moist environment will lead to moderate
   buoyancy this afternoon across the FL Peninsula near and south of a
   stalled front. A few thunderstorms could produce strong/locally
   severe-caliber downdrafts this afternoon within a weak deep-layer
   shear environment.

   ..Guyer/Dean.. 06/27/2017

   CLICK TO GET WUUS01 PTSDY1 PRODUCT

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

        
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Page last modified: June 27, 2017
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