SPC Forecast Products

SPC - No watches are valid as of Tue Sep 29 13:45:01 UTC 2020

No watches are valid as of Tue Sep 29 13:45:01 UTC 2020.

SPC - No MDs are in effect as of Tue Sep 29 13:45:01 UTC 2020

No Mesoscale Discussions are in effect as of Tue Sep 29 13:45:01 UTC 2020.

SPC Sep 29, 2020 1300 UTC Day 1 Convective Outlook

SPC 1300Z Day 1 Outlook
      
Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0736 AM CDT Tue Sep 29 2020

Valid 291300Z - 301200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THIS
AFTERNOON/EVENING FROM NORTHEASTERN FL TO EASTERN VA...

...SUMMARY...
Isolated damaging gusts will be possible this afternoon/evening from
northeastern Florida across the Carolinas to eastern Virginia.

...Northeastern FL to eastern VA this afternoon/evening...
Within a large-scale trough over the eastern CONUS, an embedded
shortwave trough over the lower MS Valley this morning will move
northeastward to the southern Appalachians this evening and the
Mid-Atlantic overnight.  At the surface, cyclogenesis is expected
today along a surface cold front immediately east of the
Appalachians, and the surface cyclone will develop
north-northeastward to northern New England by the end of the
period.  East of the cyclone and cold front, boundary-layer
dewpoints in the low 70s will continue to spread northward across
the Carolinas and southeastern VA.

Despite the increase in low-level moisture, buoyancy will remain
somewhat limited in the warm sector as a result of poor midlevel
lapse rates.  Still, pockets of surface heating will support MLCAPE
of 500-1000 J/kg.  Concurrently, deep-layer vertical shear will
increase with the approach of the midlevel trough from the
southwest, such that effective bulk shear will reach 40-50 kt.  The
modest CAPE and long, straight hodographs will favor a mix of line
segments or weak supercells along or just ahead of the surface cold
front, with the main concern being the potential for isolated
damaging gusts this afternoon/evening.

..Thompson/Jewell.. 09/29/2020


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