SPC 0730Z Day 3 Outlook
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