702
ACUS48 KWNS 090837
SWOD48
SPC AC 090835

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0335 AM CDT Sun Mar 09 2025

Valid 121200Z - 171200Z

...DISCUSSION...
...Day 4/Wed - ArkLaTex vicinity...

A shortwave upper trough is forecast to develop east from the
southern Rockies/northern Mexico to the Lower MS/TN Valley vicinity
on Wednesday. Forecast guidance generally keep the stronger midlevel
jet streak over central/southern TX into the Lower MS Valley.
Surface cyclogenesis is expected to remain modest, but some increase
in southerly low-level flow across the western Gulf with transport
mid 50s to low 60s F dewpoints into the ArkLaTex and Ozark Plateau
region. Cooling aloft will support steepening midlevel lapse rates,
and this will contribute to modest elevated instability. Forecast
soundings suggest boundary layer inhibition will likely subdue
potential for surface-based convection. Nevertheless, some potential
for isolated strong to severe storms capable of producing hail
appears possible. Overall confidence in unconditional 15 percent
probabilities is too low to delineate any severe area at this time,
but some low-end probabilities may become necessary in subsequent
outlooks.

...Day 6/Fri - Mid to Lower MS Valley vicinity...

A powerful upper cyclone and attendant trough is expected to develop
east across the Plains toward the MS Valley on Friday. An intense
southwesterly jet (100+ kt at 500 mb) is expected to be oriented
from the southern Plains to the Mid-MS Valley by Friday evening.
Meanwhile, a rapidly intensifying surface cyclone will shift
northeast from the central Plains to the Upper Midwest vicinity
through the period. Strong southerly low-level flow ahead of this
low and an attendant eastward-advancing cold front will support
rapid northward transport of Gulf moisture. While details regarding
quality of northward moisture transport remain, this overall pattern
will be very favorable for a regional severe weather episode from
late Friday afternoon into early Day 6/Sat morning.

Overall, cross-model consistency has improved compared to the past
couple of days, and guidance generally appears to be converging on
similar solutions. When compared with the operational ECMWF, the
operational GFS remains a bit further north with the placement of
the low-level and upper-level cyclones, as well as northward extent
of better moisture return. However, the GEFS and EPS ensemble means
are quite similar. While this indicates there is still a moderate
degree of spread in the north and east extent of severe potential,
the envelop is narrowing, and a broad area favorable for an
all-hazards severe episode is expected on Friday/Friday night,
centered on the Mid to Lower MS Valley vicinity. This trends is also
aligned with SPC and NSSL experimental machine learning guidance.
Given uncertainties still exist regarding timing and location of key
features, as well as with northward extent of deeper moisture
return, this area is likely to change/shift some over the coming
days as details become better resolved (and higher probabilities
will likely become necessary as well).

...Day 7/Sat - Southeast vicinity...

While the upper cyclone from Day 6/Fri will lift northeast over the
Upper Great Lakes into Canada on Saturday, the base of the
larger-scale upper trough over the southern Plains will eject east
over the Southeast states. Convection will likely already be
occurring ahead of the cold front, and will have access to deeper
Gulf moisture downstream across MS/AL. The north and east extent of
severe potential is uncertain as the evolution of the system on
Friday will impact downstream potential. Nevertheless, the overall
pattern will be favorable for a continuation of severe potential
into Saturday given strong vertical shear overlapping a seasonally
moist and at least modestly unstable airmass.

...Day 8/Sun - Mid-Atlantic vicinity...

An upper trough will continue to shift east across the eastern U.S.
on Sunday. While strong deep-layer flow will overspread the region
in conjunction with a moist boundary-layer ahead of an
eastward-advancing cold front, it is uncertain how much
destabilization will be able to occur. Trends will be monitored for
possible severe probabilities in the coming days, but current
predictability is low.

..Leitman.. 03/09/2025