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Sep 22, 2017 1730 UTC Day 2 Convective Outlook
Updated: Fri Sep 22 17:24:14 UTC 2017 (Print Version | 20170922 1730Z Day 2 shapefile | 20170922 1730Z Day 2 KML)
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 Forecast Discussion

   SPC AC 221724

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1224 PM CDT Fri Sep 22 2017

   Valid 231200Z - 241200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS CENTRAL NEBRASKA
   TO CENTRAL MINNESOTA...

   ...SUMMARY...
   Isolated damaging wind gusts are possible from central Nebraska
   northeastward to central Minnesota Saturday afternoon and evening.

   ...Synopsis...
   A large-scale trough will encompass the western U.S. on Saturday,
   with the eastern extent advancing slowly into the central and
   northern Plains.  Meanwhile, a strong mid- to upper-level ridge will
   persist east of the Great Plains.  Between these two systems,
   strong,meridionally oriented mid-level flow will extend from the
   southern Rockies/High Plains northward to the Dakotas and northern
   MN.
    
   At the surface, an expansive surface anticyclone, generally anchored
   over the central and southern Appalachians, will persist from the
   East Coast and Great Lakes to the southern Plains and Gulf of
   Mexico.  A weak low located in vicinity of the CO/KS border should
   move little this forecast period, while a stationary front extends
   through central NE to central MN.  A weak lee trough/dryline will
   extend southward across eastern NM.  A broad area of southerly winds
   across the warm sector will maintain an unseasonably moist
   environment from NE into the Upper Midwest, with surface dew points
   in the lower 60s in NE and around 70 F in MN.
     
   ...Central Nebraska northeastward to central Minnesota...
   The strongest flow aloft and deep-layer shear are expected to
   generally lag the stationary front this forecast period.  The
   presence of a moisture rich environment (including precipitable
   water values up to 1.5 inches) in vicinity of the stationary
   boundary and surface heating in the warm sector should result in
   moderate buoyancy.  However, modest mid-level lapse rates (near 7
   C/km) and the lack of better forcing for ascent during peak heating
   suggest the strength of updrafts should be tempered.  These factors
   preclude an increase in severe probabilities with this outlook
   issuance.

   Deep-layer shear of 20-30 kt near the front should support loosely
   organized storm clusters and linear segments capable of producing
   isolated damaging wind gusts, especially where storms can move
   through a boundary layer with steep low-level lapse rates and
   greater DCAPE.  Isolated hail cannot be ruled out with any of the
   stronger storms.  The Marginal severe threat should wane after
   sunset, given the loss of surface heating.

   ..Peters.. 09/22/2017

   CLICK TO GET WUUS02 PTSDY2 PRODUCT

   NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 0600Z

        
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Page last modified: September 22, 2017
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