SPC AC 010729

   Day 3 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0229 AM CDT Sat Aug 01 2020

   Valid 031200Z - 041200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PORTIONS OF
   THE APPALACHIANS INTO THE MID ATLANTIC...PORTIONS OF CO/NM...AND
   COASTAL REGIONS OF THE CAROLINAS...

   ...SUMMARY...
   A few severe thunderstorms will be possible Monday afternoon and
   evening from portions of the Appalachians to the Mid Atlantic, and
   also across portions of Colorado and New Mexico. A couple of
   tornadoes will also be possible across coastal regions of the
   Carolinas associated with Isaias.

   ...Synopsis...
   A broad upper trough is expected to persist across the
   central/eastern CONUS on Monday, while some dampening of the western
   ridge is expected as a shortwave trough moves across the northern
   Rockies. T.C. Isaias is currently forecast to accelerate
   northeastward through the period, potentially impacting the
   Carolinas by Monday night. 

   ...Portions of the Appalachians into the Mid Atlantic...
   A belt of moderate southwesterly flow is forecast to remain in place
   from parts of the Appalachians to the Mid Atlantic through the
   period. As rich low-level moisture streams back into the region in
   advance of T.C. Isaias, moderate instability may redevelop by
   afternoon prior to the development of increasingly widespread
   convection by Monday afternoon/evening. Effective shear of 25-40 kt
   will support the potential for some organized convection, with a
   threat of locally damaging wind and perhaps a tornado or two. 

   ...Coastal Carolinas...
   The current forecast track of Isaias would bring the northeast
   quadrant of the circulation into coastal regions of the Carolinas by
   Monday afternoon/evening. A Marginal Risk area has been included for
   the potential of a couple tornadoes, based on the forecast track and
   recent model guidance, though considerable uncertainty remains. 

   ...CO/NM...
   A similar northwesterly flow regime will be in place across portions
   of CO/NM into west TX compared to previous days. At least isolated
   convection will be possible within an environment favorable for
   organized convection. The strongest cells may be capable of hail and
   locally severe wind gusts. 

   ...Midwest into the OH Valley...
   Scattered thunderstorms will be possible from the Midwest into the
   OH Valley Monday afternoon/evening, along and ahead of a cold front.
   Midlevel flow is expected to be weaker across this region compared
   to areas further east, but still may be sufficient to support 20-30
   kt of effective shear and the potential for a few organized
   multicells capable of hail and locally strong wind gusts.
   Probabilities may be added for this region once details regarding
   the magnitude of shear and destabilization become clearer.

   ..Dean.. 08/01/2020

   CLICK TO GET WUUS03 PTSDY3 PRODUCT

   NOTE: THE NEXT DAY 3 OUTLOOK IS SCHEDULED BY 0730Z