SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0248 PM CDT Wed Jun 14 2023
Valid 142000Z - 151200Z
...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS FROM THE
ARKLAMISS ACROSS AL INTO SOUTHWEST GA...
...SUMMARY...
Significant severe thunderstorms capable of producing all severe
hazards, including very large hail, swaths of intense wind
gusts/damage, and tornadoes, are expected from the ArkLaTex into the
Southeast this afternoon into tonight.
...20Z Update...
...Arklatex into GA...
Recent surface analysis places a residual outflow boundary from the
MLU (in northeast LA) vicinity eastward to near MGM (in central AL)
and then more southeast to north of TLH (in the eastern FL
Panhandle). Most of the ongoing storms are just north of this
boundary, including the few tornadic supercells over southeast GA.
This area was addressed in recently issued MCD 1043, which mentions
that a corridor of greater tornado potential may be evolving across
portions of southern GA. Longer-lived supercells will likely
continue with a risk for large hail and tornadoes (possibly strong)
for the next couple of hours.
Development farther west across northern LA has shown a trend
towards more linear organization/upscale growth, with the outflow
boundary potentially providing a favorable corridor for a
significant severe-wind threat into central MS. Severe Thunderstorm
Watch #293, which contains Particularly Dangerous Situation wording,
was recently issued to cover this threat.
Several bowing segments and supercells are ongoing between these two
areas (i.e. across central MS and central AL), with very large hail
and strong gusts possible with these storms as well. Given the
robust vertical shear and strong/extreme buoyancy, the severe threat
is expected to continue across these areas throughout the evening as
well.
...North/Central TX...
Warm and very moist conditions are in place across the region, with
the recent 18Z FWD sampling almost 5000 J/kg of MLCAPE. An outflow
boundary extends from just southwest of PRX southwestward through
the Metroplex and SEP to about 50 miles south of ABI. This boundary
could be the focus for additional storm development this afternoon.
Even so, any development will be battling significant dry air
entrainment, which leads to some uncertainty regarding storm
coverage. Regardless, any storms that do persist should be
accompanied by very large hail (3+" in diameter) and strong
downdrafts.
..Mosier.. 06/14/2023
.PREV DISCUSSION... /ISSUED 1126 AM CDT Wed Jun 14 2023/
...ArkLaTex to GA through tonight...
The unusually strong flow pattern continues from the southern Plains
eastward to the Southeast, with 50+ kt midlevel flow across the
corridor, coincident with steep midlevel lapse rates and strong
buoyancy. Embedded speed maxima will move generally eastward
through this corridor, around the southern periphery of the midlevel
closed low over the lower Great Lakes. The primary severe threat
will continue through the afternoon and into tonight from the
ArkLaTex across MS/AL into southern GA.
Multiple clusters of severe storms are ongoing, including both
supercells and line segments. The cluster in northern MS will
likely persist through the afternoon while moving east-southeastward
across central AL, where additional supercell development is
expected within the warm sector ahead of the cluster. The
environment of large buoyancy (MLCAPE 3000-4000 K/kg) and effective
bulk shear in excess of 60 kt is quite unusual for mid June into the
I-20 corridor, and this will support an unusually high threat for
severe storms (including significant severe events). Supercells
will be capable of producing isolated very large hail to near 3
inches in diameter with the supercells forming in northeast TX, and
with supercells farther east into AL. A complex storm evolution is
expected from MS across AL into GA along the buoyancy gradient, as
the ongoing clusters and new storms interact and potentially support
upscale growth into larger clusters.
Swaths of wind damage, some up to 80 mph, can be expected with the
MS/AL clusters this afternoon and into GA along the residual outflow
boundary. This boundary will locally enhance low-level shear, with
the potential for a few tornadoes (a couple of which could be
strong), from southwest GA into southeast/central AL with both the
isolated supercells and with embedded circulations in any larger
clusters. Another cluster could evolve from the northeast TX
supercells, and this convection will have a corridor of strong
instability to support its maintenance across northern LA into
central MS and eventually AL later this afternoon into early
tonight. The initial supercells could produce very large hail,
while upscale growth will favor swaths of damaging winds (some
significant), as well as a few tornadoes.
...Central TX this afternoon/evening...
Strong-extreme buoyancy is expected again across central TX, but
forcing for ascent will be weak. If sufficient heating/mixing can
occur, an isolated storm may form this afternoon along the surface
front into central TX. The environment conditionally favors
splitting supercells with very large hail, though storm
formation/coverage is uncertain.
...Northern Mid-Atlantic/southern New England this afternoon...
Pockets of surface heating will drive weak buoyancy to the east of
the low across southern New England, where isolated strong-severe
storms may occur (see MD #1037 for additional information).
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