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    Day 2 Outlook >
Jul 22, 2017 0600 UTC Day 1 Convective Outlook
Updated: Sat Jul 22 05:59:10 UTC 2017 (Print Version | 20170722 1200Z Day 1 shapefile | 20170722 1200Z Day 1 KML)
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 Forecast Discussion
   SPC AC 220559

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1259 AM CDT Sat Jul 22 2017

   Valid 221200Z - 231200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE OHIO
   VALLEY EASTWARD TO THE MID ATLANTIC...

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE UPPER
   MISSISSIPPI VALLEY...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE CENTRAL
   PLAINS EASTWARD TO THE ATLANTIC COAST...AND OVER THE UPPER
   MISSISSIPPI VALLEY...

   ...SUMMARY...
   Scattered severe storms capable of hail or damaging wind are
   possible from the Ohio Valley eastward into the Mid Atlantic, and
   across parts of the upper Mississippi Valley today. More isolated
   activity is expected across the central Plains.

   ...Synopsis...
   A progressive shortwave trough will dive southeastward across the
   upper MS Valley with increasing westerly surface winds behind a cold
   front aiding in lift. To the east, modest west/northwesterly flow
   aloft will extend from the OH Valley into the Northeast, with early
   day storms associated with a weak disturbance roughly over IN/OH
   early in the day. A moist and unstable air mass will remain across
   the entire region, with an extensive low pressure trough from KS to
   the Mid Atlantic, as well as across the upper MS Valley.

   ...IN/OH eastward to the Atlantic coast...
   Substantial uncertainty exists regarding the timing of severe storms
   today given likely ongoing storms early in the day. Most CAM
   solutions suggest storms will extend from IL into OH at the start of
   the period, moving across OH and PA during the day with perhaps some
   low-end severe risk. Any outflow from this activity may provide a
   focus for diurnally driven storms during the afternoon, most likely
   across the slight risk area. Increasing westerly flow aloft and PWAT
   suggest a few fast moving storms capable of damaging outflow winds.
   Hail is also possible with any discrete storms away from the more
   organized outflows.

   ...MN...WI...Upper MI...
   A weak pre-frontal trough will deepen over MN during the day as a
   substantial shortwave trough provides cooling aloft. Early activity
   now over the Dakotas should traverse the Arrowhead and move into
   northern WI and the U.P. of MI during the day, perhaps with a
   continued wind or hail threat. New afternoon activity is then
   expected along any outflows from that activity, across
   central/eastern WI, with other isolated cells possible farther west
   over MN where wind profiles appear to favor splitting cells capable
   of large hail. Isolated significant hail is possible given long
   hodographs, ample instability and cool temperatures aloft.

   ...Northern KS...east central CO...central MO...
   Very hot temperatures will lead to deep mixed layers and weak
   instability near the east-west oriented surface trough. Little upper
   support for ascent exists, but at least isolated late afternoon
   storms are likely capable of locally damaging winds or marginally
   severe hail.

   ..Jewell/Dean.. 07/22/2017

   CLICK TO GET WUUS01 PTSDY1 PRODUCT

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

        
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Page last modified: July 22, 2017
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