[ You are not allowed to view attachments ] SPC AC 141730
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1230 PM CDT Fri Mar 14 2025
Valid 151200Z - 161200Z
...THERE IS A HIGH RISK OF SEVERE THUNDERSTORMS IN CENTRAL/SOUTHERN
PARTS OF MS/AL...
...SUMMARY...
A tornado outbreak is likely on Saturday across the central Gulf
Coast States and Deep South into the Tennessee Valley. Numerous
significant tornadoes, some of which should be long-track and
potentially violent, are expected on Saturday afternoon and evening.
The most dangerous tornado threat should begin across eastern
Louisiana and Mississippi during the late morning to afternoon,
spread across Alabama late day into the evening, and reach western
parts of the Florida Panhandle and Georgia Saturday night.
...Central Gulf Coast/Deep South/TN Valley...
After collaboration with WFOs BMX/JAN/MOB, an upgrade to a level
5-HIGH risk appears warranted for the most likely corridor of
potentially violent tornadoes, peaking tomorrow afternoon and
evening. A broader level 4-MDT risk has been expanded somewhat
eastward for the nocturnal significant tornado threat.
An intense mid-level jet, 100-110 kts at 500 mb, will eject through
the basal portion of a broad southern Great Plains shortwave trough.
This will induce secondary cyclogenesis along an initially
slow-moving baroclinic zone from the Ark-La-Tex to the central Great
Lakes. Another day of air mass modification ahead of this wave will
yield a pronounced plume of rich northwest Gulf moisture that should
be pristine across southeast LA and southern MS through late
morning. As mid-level height falls overspread the diurnally warming
air mass, increasing convective development is expected along the
deepening baroclinic zone, as well as residual outflows to its
northeast in the TN Valley from prior late D1 convection.
Steep mid-level lapse rates atop the richly moist boundary layer
will yield at least moderate MLCAPE from 1500-2500 J/kg across
eastern LA into central MS. Vertically veering wind profiles with
strong anvil-level divergence amid the favorable instability should
support robust updrafts and intense supercells. Low-level shear will
strengthen midday through the afternoon, yielding potential for a
tornado outbreak.
The most probable convective corridor will be along the effective
outflow boundary across central/northern parts of MS into north AL
and south TN. Along and south of this will be the most favored
corridor for long-tracked, discrete supercells. These will likely
develop within north/south-oriented confluence bands as increasing
large-scale ascent becomes coincident with the peak heating cycle.
A volatile combination of kinematic/thermodynamic parameters will
support potential for long-track, EF3+ tornadoes. The overall
spatial extent of this threat will be modulated by the degree of
boundary-layer heating within the mid to upper 60s dew point plume,
along with where exactly the large-scale outflow boundary sets up
from late D1/early D2.
Significant tornado potential, along with very large hail and
destructive damaging wind gusts, should persist into Saturday night.
Greater potential for a broken to linear band of thunderstorms is
anticipated by this time, but wind profiles will still strongly
favor supercells. As such, a mix of all three hazards may continue
with sig severe hail potential favored south and sig severe wind
favored north as the convective band spreads towards the southern
Appalachians and the northeast Gulf Coast.
...OH Valley to central Great Lakes...
Forecast confidence remains low with regard to severe potential
north of the TN Valley. Guidance continues to differ on the degree
of diurnal destabilization in the wake of the D1 shortwave trough
and deep cyclone tracking into northern Ontario. With increasingly
widespread Mid/Deep South to TN Valley thunderstorms during the day
Saturday, the northward extent of appreciable surface-based
instability appears highly questionable within a predominately
meridional deep-layer wind profile. Given the fast flow regime
though, even weak convection late afternoon through Saturday night
will pose some risk for locally strong gusts and a tornado.
..Grams.. 03/14/2025
