Source: US National Oceanic and Atmospheric Administration
SPC AC 041253
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0653 AM CST Mon Nov 04 2024
Valid 041300Z – 051200Z
…THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM PARTS OF
THE SOUTHERN PLAINS INTO THE OZARKS…
…SUMMARY…
Tornadoes (some strong), large hail, and severe thunderstorm gusts,
are expected today into tonight from the Southern Plains into the
Ozarks and mid Mississippi Valley.
…Synopsis…
A high-amplitude mid/upper-level pattern will continue over the
CONUS, dominated by a trough now located from a low over northern
SK, to eastern MT, central WY, western CO, through another low over
western NM south of GNT, and across western Chihuahua to the central
Mexican Pacific Coast. A strong, basal shortwave trough was
apparent in moisture-channel imagery south through southwest of the
low, over the borderlands of southwestern NM and southern AZ. As
the shortwave trough pivots around the broader-scale flow field
today — across west TX to the South Plains/Permian Basin regions —
the low should shift eastward roughly along I-40 to near TCC, then
lose definition near the TX line around 00Z. By 12Z, the shortwave
trough should become positively tiled and extend from eastern KS
across southwestern OK to the lower Pecos Valley of west TX,
somewhat ahead of the synoptic-scale trough.
At the surface, 11Z analysis showed an outflow-reinforced warm-
frontal zone over southwest, south-central and east-central OK,
moving slowly northward. A surface low was drawn over west-central
TX near ABI, and is forecast to move northeastward along the
combined convective/outflow boundary today. By 00Z, the low should
be near PNC, with cold front across south-central/southeastern OK,
then roughly down the I-35 corridor in TX. The warm front should
extend from the low east-northeastward over central/northeastern MO.
By 12Z tomorrow, the low should reach the northern MO/southern IA
vicinity, with cold front to southeastern OK and east-central to
deep south TX.
…Southern Plains to mid Mississippi Valley…
A band of convection largely north of the warm front is moving
through central OK at this time, with marginal potential for severe
gusts or a tornado. See SPC mesoscale discussion 2201 for near-term
details.
Convection farther south along/ahead of the cold front is expected
to gradually organize as a QLCS through the remainder of the
morning, including near the fresh convective boundary trailing the
ongoing activity over OK. This should occur as the activity moves
obliquely across the warm front/outflow boundary preceding it, and
into a more-favorable, slowly northward-shifting boundary layer now
across southern OK and northwest/north-central TX. Given the
supportive low-level and deep-layer shear (with effective-shear
magnitudes commonly 45-55 kt and 200-400 J/kg effective SRH),
embedded mesovortices with tornado potential should exist, as well
as the typical threat for severe gusts locally maximized near
LEWP/bow formations. Due to the lack of a substantial EML and
related weak MLCINH in the free warm sector, gradual buildup of
convection is also expected ahead of the QLCS, with at least a few
warm-sector supercells ultimately evolving and interacting with the
outflow boundary. These would pose a threat for a few tornadoes, as
well as large hail and damaging gusts, in an environment
characterized by upper 60s to low 70s F surface dewpoints, low LCL,
and enlarging hodographs.
The severe threats with the QLCS and foregoing supercells should
shift eastward and northeastward across the outlook area through the
period, with the convective band sweeping up cells just ahead of it.
Meanwhile the warm front will shift northward to near or even a bit
north of the I-44 corridor in northeastern OK/MO. Meanwhile
additional supercells may develop farther east in the northward-
expanding warm sector. The most favorable parameter space for
tornadoes from all this activity should be this afternoon and
evening from south-central and eastern OK into the Ozarks of
southern MO and northwestern AR, with a relatively maximized risk of
significant (EF2+) tornado potential. Forecast soundings reasonably
depict enlargement of the preconvective hodographs from late
afternoon into evening over this region, with around 30-kt shear
vectors and 150-200 J/kg SRH just in the lowest 1/2 km.
The severe threat should persist into the mid Mississippi Valley
late tonight, gradually winding down as the projected inflow layer
becomes less unstable. The eastern bound remains uncertain, but
somewhat more room has been added on the marginal outlook from IL-AR
to account for that uncertainty. The backbuilding convective band
into north and central TX — and the Arklatex tonight — also will
pose a tornado and severe-gust threat, but with hodographs and deep
ascent somewhat weaker than farther north.
..Edwards/Mosier.. 11/04/2024
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