Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0338 AM CST Sat Feb 04 2017
Valid 071200Z - 121200Z
Model differences/uncertainty persist at this time, with respect to
evolution of the large surface storm system to move across the
eastern third of the U.S. Day 4/Tuesday. However a somewhat more
consistent depiction of major features within the ECMWF and GFS
permits what appears to be a reasonable ability to highlight a 15%
severe risk area from roughly the mid Ohio Valley southward into the
central Gulf coastal region. Within this area, somewhat modest but
sufficient CAPE development should occur ahead of a
strengthening/advancing cold front -- particularly from the Ohio
Valley southward -- to permit development of fairly robust updrafts
by afternoon. Though what appears likely to be a westerly component
to the low-level warm-sector flow field should limit tornado
potential, large hail and locally damaging winds will be possible --
with potential for both rotating storms and lines/line segments.
Convection should eventually weaken overnight, especially over
northern parts of the risk area as storms move into a less-unstable
environment. Risk may linger farther south, as storms move into the
southern Appalachians overnight.
By Day 5/Wednesday, greater uncertainty exists, with the GFS
depicting the front to have moved off the Atlantic and Gulf coasts
by midday, while the ECMWF lingers a trailing, west-to-east portion
of the front over the Gulf Coast States/Carolinas through the
afternoon. Given these differences, will not highlight a risk area
at this time for Day 5.
Risk appears minimal for Day 6, but potential for convection could
increase into the central U.S. Day 7 and into the East Day 8 as the
next storm system shifts out of the Rockies. Model differences are
substantial enough with respect to the details, however, that no
risk areas will be considered at this time.