SPC AC 221956

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0256 PM CDT Fri May 22 2020

   Valid 222000Z - 231200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER NORTH
   TEXAS...

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM NORTHERN
   TEXAS INTO ARKANSAS...AND OVER THE CAROLINAS...

   ...SUMMARY...
   Severe storms remain possible today from north Texas into Arkansas,
   as well as across parts of the Carolinas.

   ...North TX, southern OK, MO into AR...
   Little change is required to this area as storms have not yet formed
   over TX as of 20Z. Very strong instability exists over much of TX,
   and continued heating will likely lead to scattered severe storms
   later this afternoon near the residual outflow boundary. Dewpoints
   continue to rise into southern OK as well, a combination of vertical
   mixing as well as evapotranspiration. This may support any
   left-moving storms with hail or wind threat. As such, have nudged
   the Slight Risk back north a bit.

   Farther north into MO and AR, outflow-cooled air is currently
   stabilizing much of northwest AR into southern MO. However, cool
   temperatures aloft exist along with a midlevel speed max and
   continued heating. Given southwesterly 850 mb winds around 25 kt,
   moisture/instability may again increase, with scattered storms from
   northeast OK into southwest MO. Therefore, have re-adjusted low
   severe probabilities back north.

   ...Southeast...
   A relatively unstable air mass may slowly spread north across TN,
   ahead of a complex of storms over AR. This may support isolated
   strong wind gusts, despite the current stabilizing effects of the
   Carolinas MCS. Otherwise, also expanded the Marginal Risk southward
   into AL where instability is quite strong, supporting vigorous
   multicell storms. A damaging gust or marginal hail report is
   possible for a few hours until the air mass is overturned.

   ..Jewell.. 05/22/2020

   .PREV DISCUSSION... /ISSUED 1132 AM CDT Fri May 22 2020/

   ...MO/AR...
   A long-lived MCS is tracking across southern MO and western AR. 
   This cluster of storms has not been particularly strong for the past
   few hours, but slow heating across central AR may lead to
   intensification by early afternoon.  Ample low-level moisture and
   moderate CAPE values, coupled with stronger westerly midlevel flow
   just to the north may be sufficient for damaging/severe winds along
   the leading edge of the MCS.  It is unclear how far east these
   storms may remain intense, but have extended the SLGT to near the MS
   river for later today.

   ...TX...
   The aforementioned MCS has resulted in an expansive cold pool and
   associated outflow boundary that has pushed into north TX.  This
   cold pool is much larger than any morning model guidance, which
   lends significant uncertainty to convective evolution later today. 
   The outflow boundary is slowing its southward motion, and is likely
   to stall across north TX.  Strong heating north of the boundary,
   along with a strengthening southerly low-level jet later this
   afternoon/evening still appear favorable for intense thunderstorm
   development.  Large CAPE and sufficient deep-layer shear will result
   in supercell storms capable of very large hail.  Interaction with
   the outflow boundary may also result in a tornado or two.

   ...Carolinas...
   A linear MCS is currently moving across the mountains of north
   GA/western NC.  These storms will move into northern SC and much of
   NC this afternoon and early evening.  Visible satellite imagery
   shows strong heating and considerable destabilization occurring in
   this region.  Strengthening flow aloft will also help to
   organize/maintain the storms.  Present indications are that activity
   will intensify early this afternoon and pose a risk of damaging wind
   gusts.  Therefore have added a SLGT risk area to this region.

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