ShelbyOhWx

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0100 AM CDT Sun Apr 28 2024

Valid 281200Z - 291200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PART OF
EAST TEXAS...NORTHWEST LOUISIANA...FAR EASTERN
OKLAHOMA...WESTERN-CENTRAL ARKANSAS AND SOUTHWEST TO SOUTH-CENTRAL
MISSOURI...

...SUMMARY...
Severe thunderstorms are likely today from parts of east Texas and
northwest Louisiana north-northeastward into southwest Missouri.
Damaging winds and a few tornadoes are expected along the stronger
parts of the line. A couple of strong tornadoes could occur from
southwest Arkansas into east Texas. A more isolated severe threat is
expected today over parts of the lower to mid Missouri Valley.

...East Texas/Ark-La-Tex/Ozarks...
A large linear MCS will move eastward across the Ozarks and
Ark-La-Tex early in the period. The line is expected to become
unorganized after daybreak and dissipate by late morning. A moist
and unstable airmass is likely to remain mostly undisturbed across
much of east Texas and Louisiana. This airmass is forecast to advect
northward across the Ark-La-Tex during the afternoon. On the
large-scale, a negatively tilted mid-level trough will move across
the southern and central Plains today. As surface temperatures warm,
thunderstorms will reform along the western edge of the warm sector
by mid-afternoon. The convection is expected to organize into a
line, producing wind damage and hail, moving eastward across the
Ark-La-Tex and Ozarks during the late afternoon. The greatest severe
threat will likely be along the southern half of the line, from
southwest Arkansas and far southeast Oklahoma south-southwestward
into east Texas.

RAP forecast soundings at 00Z/Monday across far southwest Arkansas
and in northeast Texas have MLCAPE ranging from 1500 to 3000 J/kg,
with 0-6 km shear generally from 35 to 45 knots. Also, 0-3 km
storm-relative helicity is forecast to increase into the 200 to 300
m2/s2 range during the late afternoon and early evening, as a 50 to
60 knot low-level jet strengthens. This environment will be
favorable for tornadoes with embedded supercells, and with rotating
elements near the leading edge of the line. A couple of strong
tornadoes will be possible, mainly in the Ark-La-Tex and in east
Texas, where instability is expected to be greatest. Hailstones
greater than two inches in diameter could occur near the southern
end of the line, if a couple supercells can remain semi-discrete.
The more intense bowing segments will likely be accompanied by wind
damage. Although a substantial severe threat is expected as far
south as southeast Texas, there could be a gap in the line across
part of east Texas where the severe threat is locally minimized. On
the northern end of the line in the Ozarks, the magnitude of the
severe threat will be conditional upon destabilization in the wake
of the morning MCS. The severe threat associated with the line
should persist into the late evening as the new MCS approaches the
Mississippi River.

...Lower to Mid Missouri Valley/Mid to Upper Mississippi Valley...
An upper-level trough will move eastward across the lower to mid
Missouri Valley today. Ahead of the trough, a moist airmass will be
in place across much of Missouri northward into southern Iowa. As
surface heating takes place today, thunderstorms are forecast to
develop along the western edge of the moist sector from east-central
Kansas into southeast Nebraska. The storms will move eastward into
Missouri and southern Iowa during the afternoon. RAP forecast
soundings near Kansas City by 21Z have MLCAPE near 1200 J/kg, with
0-6 km shear around 60 knots. This, combined with steep low to
mid-level lapse rates should support a severe threat during the
afternoon. The primary hazards should be wind damage and hail. As
convective coverage increases during the late afternoon and early
evening, a line is expected to organize. Wind damage should become
the primary threat as it approaches the Mississippi River during the
evening.

..Broyles/Thornton.. 04/28/2024

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Day 2 Convective Outlook  
NWS Storm Prediction Center Norman OK
1257 AM CDT Sun Apr 28 2024

Valid 291200Z - 301200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PARTS OF
CENTRAL/SOUTH TX INTO THE LOWER MS VALLEY...

...SUMMARY...
Isolated strong to severe thunderstorms will be possible on Monday
from parts of central and south Texas into the lower Mississippi
Valley.

...Synopsis...
A shortwave trough near the upper Great Lakes region at the start of
the period is forecast to gradually weaken and move northeastward on
Monday. In its wake, a low-amplitude shortwave trough is forecast to
move across the southern Plains. Across the West, a shortwave trough
and related mid/upper-level jet will move through the Northwest
toward the northern Rockies by Monday evening. 

...ArkLaTex into the Lower MS Valley...
A storm cluster will likely be ongoing somewhere near or east of the
ArkLaTex region Monday morning, aided by a persistent low-level jet
and the approaching low-amplitude shortwave trough. Depending on the
timing of the cluster, some downstream diurnal destabilization could
support a threat for isolated hail, damaging wind, and possibly a
tornado into the lower MS Valley region. The threat should begin to
wane by evening as instability weakens with time and eastward
extent. 

...Parts of the southern Plains...
A nebulous but nonzero severe threat appears evident over parts of
Texas on Monday. While stronger ascent will move east/northeast of
this region, strong heating of a moist airmass will result in
moderate to locally strong destabilization across parts of south and
perhaps central TX, and isolated storm development will be possible
as CINH weakens. Deep-layer shear will remain sufficient for some
storm organization, so any sustained development would pose a threat
for hail and isolated severe gusts. A broad but uncertain Marginal
Risk has been maintained for this regime. 

There is some signal in guidance for isolated storm development near
the northwest fringe of returning low-level moisture into northwest
OK and southern KS, even though this region will be in the immediate
wake of the departing shortwave trough. Given the uncertainty
regarding both magnitude and northward extent of more favorable
low-level moisture, probabilities have not been introduced in this
area, but a strong storm or two cannot be ruled out within this
regime. 

...Parts of the Mid MS and OH Valleys into the lower Great Lakes
region...
A weakening cold front will move through parts of the Mid MS and OH
Valleys during the day on Monday, with the front expected to reach
parts of the lower Great Lakes by Monday evening. While moderate
deep-layer flow will persist along/ahead of the front,
destabilization may be quite limited due to considerable cloudiness
and weakening midlevel lapse rates. A strong storm or two cannot be
ruled out along/ahead of the front, but confidence regarding the
development of adequate instability remains too low to include
probabilities.

..Dean.. 04/28/2024

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Day 3 Convective Outlook  
NWS Storm Prediction Center Norman OK
0242 AM CDT Sun Apr 28 2024

Valid 301200Z - 011200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR EASTERN
NE...WESTERN IA...NORTHWEST MO...NORTHEAST KS...

...SUMMARY...
Severe thunderstorms will be possible on Tuesday from parts of the
mid/upper Mississippi Valley into the central/southern Plains.

...Synopsis...
An amplified mid/upper-level shortwave trough is forecast to move
eastward from the northern Rockies into parts of the
northern/central Plains on Tuesday, accompanied by a strong
mid/upper-level jet. A surface wave is forecast to move from the
central Plains toward the upper MS Valley, with a separate low
expected to largely remain in place across the southern High Plains.

...Upper MS Valley into the southern Plains...
Low-level moisture will stream northward through the day from the
southern Plains into the central Plains and upper MS Valley, in
response to the approaching shortwave trough. While the richest
moisture will likely remain displaced southward of the shortwave
track, 50s to near 60F dewpoints could spread as far north as
eastern NE/western IA and southern MN by Tuesday afternoon. This
moistening beneath relatively steep midlevel lapse rates will
support diurnal destabilization, with peak MLCAPE ranging from
around 500 J/kg across southern MN to greater than 1500 J/kg across
the southern Plains. 

Thunderstorm development is expected along a weak cold front Tuesday
afternoon, as diurnal heating weakens MLCINH. The greatest coverage
of storms and strongest deep-layer shear are expected from southern
MN into parts of eastern NE and western IA, in closer proximity to
stronger ascent attendant to the shortwave. A few stronger
cells/clusters will be possible, capable of producing large hail,
damaging winds, and possibly a tornado or two. Storm coverage and
deep-layer shear will likely decrease with southward extent, though
stronger instability into parts of KS/OK could support at least an
isolated severe thunderstorm threat during the afternoon and
evening. 

A Slight Risk has been added where confidence is greatest in overlap
of greater storm coverage and shear with more favorable instability.

..Dean.. 04/28/2024

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