SPC AC 190828

   Day 3 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0228 AM CST Mon Feb 19 2018

   Valid 211200Z - 221200Z

   ...NO SEVERE THUNDERSTORM AREAS FORECAST...

   ...SUMMARY...
   Showers and embedded thunderstorms will be possible from portions of
   the southern Plains east/northeast to the Mid-Atlantic region
   Wednesday.

   ...Synopsis...
   Little change to the large-scale upper pattern over the U.S. is
   expected Wednesday, with a highly amplified trough over the Western
   and central U.S. and ridging over the Southeast and adjacent western
   Atlantic/Gulf of Mexico.  At smaller scales, short-wave troughing
   will continue to rotate around western and southern portions of the
   long-wave trough, while another prominent short-wave trough moves
   quickly across the Great Lakes and into eastern Canada.  

   At the surface, the rapid east-northeast advance of the
   aformementioned short-wave trough across the Great Lakes will allow
   similarly rapid eastward progression of a cold front across the
   Northeast and Ohio Valley -- with the front moving off the New
   England coast overnight.  However, with a corresponding increase in
   southeastern U.S. short-wave ridging aloft in the wake of the trough
   passage, and with the larger-scale western trough remaining well to
   the west, southern portions of the surface front should become
   oriented increasingly west-to-east, with little forward advance is
   it instead lingers across the Tennessee and lower Mississippi
   Valleys and into southern and eastern Texas.

   With limited instability expected ahead of the front -- particularly
   from the Tennessee Valley area northeastward, and with short-wave
   ridging increasing with time across the Southeast, thunderstorm
   coverage and intensity will likely remain subdued.  While hints
   exist that a very weak trough/vort max may cross the southern Plains
   during the period, insufficient elevated CAPE for appreciable hail
   risk is anticipated.  One area where a storm or two could evolve
   with potential for a more robust updraft is across deep south Texas
   and the lower Rio Grande Valley, near the remnant front.  While
   modestly sufficient instability could combine with marginal shear to
   suggest local/low end severe potential, the scenario remains too
   marginal and too uncertain to warrant introduction of even a low
   (5%) severe probability area at this time.

   ..Goss.. 02/19/2018

   CLICK TO GET WUUS03 PTSDY3 PRODUCT

   NOTE: THE NEXT DAY 3 OUTLOOK IS SCHEDULED BY 0830Z