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Jul 26, 2017 0730 UTC Day 3 Severe Thunderstorm Outlook
Updated: Wed Jul 26 07:30:47 UTC 2017 (Print Version | 20170726 0730Z Day 3 shapefile | 20170726 0730Z Day 3 KML)
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 Forecast Discussion
   SPC AC 260730

   Day 3 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0230 AM CDT Wed Jul 26 2017

   Valid 281200Z - 291200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM PARTS OF THE
   MID ATLANTIC REGION AND THE CAROLINAS WEST ACROSS PARTS OF THE
   SOUTHEAST...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SURROUND THE
   EASTERN/SOUTHEASTERN U.S. SLIGHT RISK...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF
   THE CENTRAL AND NORTHERN HIGH PLAINS AREA...

   ...SUMMARY...
   Strong/locally severe storms are forecast across a large portion of
   the eastern U.S. Friday, from the middle and southern Atlantic Coast
   west-southwest across the Mid South and Southeast.  A couple of
   severe storms will also be possible over parts of the central and
   northern High Plains vicinity.

   ...Synopsis...
   While large-scale upper ridging largely predominates over the
   western U.S. Friday, substantial amplification of troughing is
   forecast over the eastern U.S. with time.  While the models differ
   fairly substantially with respect to timing and track, a strong
   short-wave trough -- initially progged over the upper Great Lakes
   area -- will dig southeast toward/into the central Appalachians
   area.  

   At the surface, a fairly strong cold front is forecast to shift
   southeast into -- and across -- the Appalachians, with relatively
   substantial cyclogenesis expected to occur along the front in the
   vicinity of the Mid Atlantic region.  Again, details with respect to
   location and timing of surface system progression and
   intensification differ, but expect a cold front to extend
   southwestward across the Atlantic and Gulf Coast states through
   latter stages of the period.  Widespread -- and likely at least
   locally severe -- convection is expected to precede frontal passage.

   ...Mid South and Southeast to the middle and southern Atlantic
   Coast...
   While a large degree of uncertainty exists with respect to
   timing/location, evolution of severe convection is expected across a
   rather broad area of the southern and eastern U.S. Friday ahead of
   the advancing cold front and associated/digging upper system.  As
   enhanced/diffluent flow aloft spreads across the area ahead of the
   upper system, a favorable kinematic environment for
   organized/fast-moving bands of storms will exist.  The main
   questions at this time revolve around timing of synoptic features,
   and evolution of prior -- and ongoing -- convection, and related
   effects on heating/destabilization potential.  Given these
   questions, a broad 15%/slight risk area is being included across
   what appears to be the zone of greatest risk at this point, with
   later adjustments to area and risk level likely to be required. 
   Along with risk across portions of the Mid Atlantic area ahead of
   the anticipated track of the main vort max, the broad zone of
   enhanced/diffluent northwest flow aloft across a large portion of
   the southeast U.S. would also support potential for rather
   widespread damaging wind risk with multiple, upscale-growing bands
   of storms through the afternoon and evening hours.

   ...Portions of the central and northern High Plains...
   As weak short-wave troughing crests the upper ridge and begins to
   turn east -- and then southeast -- as it shifts across the High
   Plains, isolated/afternoon storm development is expected in a
   modestly destabilizing High Plains airmass.  Aided by upslope flow,
   storms may locally organize and move southeast off the high terrain
   through the evening, perhaps as a small MCS.  Locally damaging winds
   would likely be the primary severe risk, along with some hail
   potential before storms diminish into the overnight hours.

   ..Goss.. 07/26/2017

   CLICK TO GET WUUS03 PTSDY3 PRODUCT

   NOTE: THE NEXT DAY 3 OUTLOOK IS SCHEDULED BY 0730Z

        
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Page last modified: July 26, 2017
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