From SPC:
Within the inland advancing troughing, there appears reasonable
agreement between the ECENS/ECMWF, GEFS and GFS model output that a
significant lead short wave perturbation will accelerate
northeastward out of the Southwest across the southern Rockies late
Sunday into Sunday night. As this occurs, a rather deep cyclone is
forecast to continue to form to the lee of the Front Range during
the day, before migrating southeastward then eastward into the
adjacent high plains. Although it still appears that low-level
moisture return in the wake of prior low-level drying and cooling
across the northern Gulf Basin may still be on the margins for
vigorous thunderstorms, the development of steep
lower/mid-tropospheric lapse rates may compensate. Coupled with
potentially intense wind fields and strong forcing for ascent,
organized severe thunderstorm development seems probable late Sunday
afternoon into Sunday night. This may include supercells initially,
then an evolving narrow squall line.
Into the early through middle portion of next week, uncertainties
concerning a subsequent short wave emerging from the Southwest
increase. However, it appears probable that there will be at least
narrow corridors of strong to severe thunderstorm development on
following days across the southeastern Great Plains into lower
Mississippi Valley and perhaps parts of the Southeast.
From JAN:
Weather turns
active again early next week as an upper low/
shortwave
eject across the upper plains. In response to the
deepening low
pressure system, the mid/
low level jet is
progged to strengthen,
yielding strong deep
shear around 60
kts. Strong low level
directional
shear will also yield long curved hodographs, which
favor supercells and may increase
tornado potential. However, here`s
the kicker. A
low pressure system off the coast of the Carolinas
appears to severely cut the quality of
moisture return, as evidenced
by dewpoints hovering in the 58-62 range, and may greatly limit the
severe potential of this system. Even so, should
moisture trend
upwards in future guidance, and/or should any storms be able to tap
into a greater quality environment amid a favorable
shear profile,
particularly south of I-20. As a result, during this time, there may
be some severe potential for a portion of the area. This event is
still several days away, so expect changes and adjustments as more
data becomes available. In addition to perhaps some severe
potential, will also have to monitor
gradient wind potential amid a
5-7
mb pressure
gradient over the area, especially Monday into
Tuesday. There are still some uncertainties regarding timing and
evolution of this system as this time, but things should begin to
look clearer as we get closer
From MEG: (searching for instability as always)
Long-term models continue to indicate an
unsettled pattern
returning to the area early next week as a deep upper-level
trough
moves through the Mississippi Valley. Latest operational model
runs indicate some slight timing and
amplitude differences of the
upper-level
trough exist with this next system. The operational
ECMWF and Canadian solutions take on more of a negative-
tilt as a
mid- level
shortwave rotates through the Middle and Lower
Mississippi Valleys. Meanwhile, the operational
GFS remains the
slower outlier as the
trough is displaced further north across the
Midwest.
Ensemble models are in relative agreement overall and
kept rain chances towards the NBM output for this period. Upper-
level
dynamics and kinematics look great with this system.
However, limited
instability or the lack thereof will inhibit the
overall strong to
severe thunderstorm potential across the Mid-
South. Nonetheless, this potential will continue to be monitored
in subsequent model runs.