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Hazard Sat (05/26) Sun (05/27) Mon (05/28) Tue (05/29) Wed (05/30) Thu (05/31) Fri (06/01) Sat (06/02)
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Forecast Discussion - Convective Outlook

   SPC AC 270059

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0759 PM CDT Sat May 26 2018

   Valid 270100Z - 271200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER A PORTION OF
   THE NORTHERN HIGH PLAINS AND SOUTHERN FLORIDA...

   ...SUMMARY...
   Severe storms with damaging wind and large hail are expected over
   the northern High Plains this evening into the overnight. A threat
   for a couple of tornadoes will persist over south Florida.

   ...Northern High Plains...

   Storms are in the process of developing along a cold front across
   central MT as well as over the higher terrain. Southeasterly winds
   have become established in the downstream warm sector in association
   with a lee trough, maintaining a corridor of low 50s F surface
   dewpoints over eastern MT beneath steep lapse rates. Objective
   analysis and 00Z RAOB data show a reservoir of 1500-2000 J/kg MLCAPE
   from eastern MT into southwest ND and western SD. Despite presence
   of an upper ridge and onset of nocturnal cooling, several embedded
   vorticity maxima and a strengthening low-level jet will foster the
   maintenance of storms through the High Plains including ND through
   the evening and into tonight. Wind profiles with 30-40 kt effective
   bulk shear will support some high based supercell structures with
   initial discrete development. However, activity may eventually
   congeal into one or more forward propagating clusters as they
   continue east during the evening. The steep lapse rate environment
   with inverted-V low-level thermodynamic profiles will promote a
   threat for damaging wind, but large hail will also be possible,
   especially through mid evening with any discrete supercell
   structures. 

   ...South Florida...

   Subtropical storm Alberto is forecast by the NHC to continue north
   into the eastern Gulf, but with the center well west of the FL
   Peninsula. However, the outer bands are already starting to affect
   south FL and the Keys. VWP data from Key West and Miami already show
   veering wind profiles in the 0-2 km layer with around 150-200 m2/s2
   storm relative helicity, and further enlargement of low-level
   hodographs will occur tonight. However, much of the southern
   Peninsula has been affected by widespread stratiform rain resulting
   in moist adiabatic profiles and very weak instability. Nevertheless,
   at least some risk for a couple of tornadoes will exist within the
   outer bands of Alberto as the storm continues north tonight. See
   latest discussion from NHC for more information on Alberto.

   ..Dial.. 05/27/2018

    

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