SPC AC 292000

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0300 PM CDT Sat Aug 29 2020

   Valid 292000Z - 301200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER A PORTION OF
   THE NORTHEAST STATES AS WELL AS A PORTION OF THE SOUTHERN PLAINS AND
   LOWER MISSISSIPPI VALLEY REGION...

   ...SUMMARY...
   Threat for damaging wind and a tornado or two will persist from the
   Northeast States into the Middle Atlantic region this afternoon.
   Otherwise a few strong to severe storms are likely this afternoon
   into the evening from a portion of Arkansas and Oklahoma as well as
   the southern High Plains. Damaging wind and large hail are the main
   threats in these areas.

   ...Eastern States...

   Primary change to previous outlook in this area has been to remove
   most of NC from severe probabilities as low-level winds veer and the
   primary corridor of forcing for ascent moves offshore. Otherwise
   threat for isolated damaging wind and a tornado or two will persist
   this afternoon from the Northeast States into the Middle Atlantic.

   ...AR and eastern OK...

   Thunderstorms may continue developing over AR along
   southward-advancing outflow boundary this afternoon and evening with
   some potential back building into OK. Isolated damaging wind and
   hail remain possible with this activity. 

   .

   ..Dial.. 08/29/2020

   .PREV DISCUSSION... /ISSUED 1129 AM CDT Sat Aug 29 2020/

   ...East...
   Widespread cloudiness along with several stratiform areas and
   isolated convection persist from New England to NC. Severe potential
   should generally be confined to two areas: 1) across eastern NY into
   western New England and 2) from eastern NC to the Delmarva region. 

   For the eastern NY/western New England area, cloud breaks in the
   wake of the broader stratiform region are underway. This
   boundary-layer heating of a moist air mass characterized by 66-70 F
   surface dew points will yield modest MLCAPE from 1000 to 1500 J/kg
   amid weak mid-level lapse rates. As a 994-mb surface cyclone over
   southern Ontario tracks east along the Saint Lawrence Valley,
   convergence along the trailing cold front should be sufficient for
   scattered thunderstorms by late afternoon across eastern NY.
   Deep-layer shear will be sufficient for organized clusters and
   transient supercell structures with damaging winds as the primary
   hazard. A couple tornadoes are also possible from the
   Hudson/Champlain Valleys into adjacent western New England where 0-1
   km SRH is favorable. 

   For the Delmarva to eastern NC area, surface temperatures have
   already warmed into the 80s within a tropical air mass characterized
   by mid to upper 70s surface dew points. Despite poor mid-level lapse
   rates overspreading the region owing to the remnants of Laura,
   moderate buoyancy should be maintained along the coastal plain.
   Isolated to perhaps scattered thunderstorms should emanate out of
   the ongoing stratiform areas over the Piedmont. Primary risk should
   be damaging winds but a brief tornado or two is also possible given
   some curvature to the low-level hodograph. See MCD 1627 for further
   near-term forecast discussion.

   ...AR/eastern OK/southern MO...
   A short QLCS that produced severe gusts earlier this morning is in
   the process of decaying across southwest MO with a lingering
   isolated damaging wind risk in the near-term. Renewed storm
   development is expected during late afternoon into early evening
   along residual convective outflow in northern AR and a cold front in
   eastern OK. Full insolation yielding surface temperatures in the 90s
   amid dew points in the mid 70s will foster a strong to extremely
   unstable air mass with MLCAPE of 3000-4500 J/kg ahead of these
   boundaries. The belt of enhanced mid-level westerlies attendant to a
   shortwave impulse shifting east from central KS should be confined
   to the MO/AR border area, largely displaced from the more unstable
   air mass to the south. The setup should tend to foster initial
   HP-supercell structures evolving into outflow-dominated clusters.
   Large hail and severe wind gusts should be the primary hazards but a
   tornado or two is possible as well. 

   ...Southern High Plains...
   Post-frontal upslope flow will aid in scattered thunderstorms
   developing off the Sangre de Cristos and Raton Mesa by late
   afternoon. A narrow belt of confluent mid-level westerlies around 30
   kts will support a few transient supercells that should grow upscale
   into a small MCS across the Panhandles this evening. Severe wind
   gusts and some hail should be the primary hazards.

   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z