NWS Storm Prediction Center - Day 3 Convective Outlook

Feb 16, 2019 0830 UTC Day 3 Severe Thunderstorm Outlook
Updated: Sat Feb 16 08:11:28 UTC 2019
SPC Day 3 0830Z Categorical Outlook SPC Day 3 0830Z Categorical Outlook Legend

 Forecast Discussion - Day 3 Convective Outlook

   SPC AC 160811

   Day 3 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0211 AM CST Sat Feb 16 2019

   Valid 181200Z - 191200Z


   The risk of severe thunderstorms appears negligible across the U.S.
   Monday through Monday night.

   Although embedded short wave developments remain somewhat unclear,
   models indicate that larger-scale western U.S. mid-level troughing
   may undergo some amplification during this period.  It appears that
   this will occur as another in a series of short wave perturbations
   digs inland of the Pacific coast: this one to the south/southwest of
   the preceding impulses, across the Southwestern international border

   Downstream, while mid-level subtropical ridging centered near/east
   of the Bahamas remains prominent, short wave ridging within the
   mid-latitude westerlies is forecast to build, in phase with the
   subtropical stream, across lower portions of the southern Plains
   into the lower Ohio and Tennessee Valleys.  As a vigorous short wave
   impulse digs within a branch of westerlies to the north, to the
   southwest of Hudson Bay, it appears that increasingly confluent
   mid-level flow will support the southeastward development of the
   center of an expansive cold surface ridge, across the northern
   Plains through southern portions of the Great Lakes region.

   The shallow southern/leading edge of the cold surface-based air
   appears likely to advance off the south Atlantic coast, while
   remaining quasi-stationary, beneath the mid-level ridging, across
   northern portions of the Florida Peninsula through much of the
   remainder of the northern Gulf coast vicinity.  Above it, a
   southerly return flow will be maintained, including further
   moistening off a modifying boundary layer over the western Gulf of
   Mexico, into the western and central Gulf Coast states.

   In the presence of weak (but increasing) elevated instability,
   modest strengthening of the return flow (including 30-40 kt at 850
   mb) may be accompanied by steepening isentropic ascent supportive of
   increasing potential for scattered thunderstorm development by late
   Monday night.  Depending on the magnitude of CAPE and depth of the
   convective layer, the environment could become conducive to severe
   hail in the presence of strong vertical shear, mainly in a narrow
   corridor roughly across central Louisiana and adjacent portions of
   Texas and Mississippi.  However, due to a number of lingering
   uncertainties, including timing near the end of the period, severe
   probabilities still appear less than 5 percent at the present time.

   ..Kerr.. 02/16/2019



Data courtesy the Storm Prediction Center
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