820 
ACUS01 KWNS 281945
SWODY1
SPC AC 281943

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0243 PM CDT Sun Apr 28 2024

Valid 282000Z - 291200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM PARTS OF
EASTERN TEXAS ACROSS THE ARKLATEX AREA...

...SUMMARY...
Clusters of severe storms are possible through early tonight, with
the most concentrated threat for wind damage, large hail and a few
tornadoes from the ArkLaTex southward into east Texas.

...20Z Update...
Little overall change was made to the existing outlook, as
potential, as well as uncertainty, remain over a large region.

An upper trough with cool temperatures aloft remains over the
Plains, with midlevel temperature gradient from IA into eastern OK
and southwestward across northern TX. Satellite imagery as well as
surface observations continue to show gradual heating and
destabilization as clouds thin from the decaying early day MCS.
Given substantial southwest flow aloft and at least a marginally
unstable air mass over most of the region, little change was made to
most of the outlook area. The greatest severe risk looks to be
centered over eastern TX toward the ArkLaTex and toward the Sabine
Valley late, in closer proximity to stronger instability.

Farther north across eastern OK into AR and southern MO, an
increasing low-level jet late this evening and right-entrance region
of the upper jet may yield a more concentrated corridor of strong to
perhaps severe storm potential after 00Z and into the night.

..Jewell.. 04/28/2024

.PREV DISCUSSION... /ISSUED 1125 AM CDT Sun Apr 28 2024/

...East TX/LA/Southern AR...
A long-lived large nocturnal MCS that affected much of TX overnight
has weakened substantially, but remains over parts of east TX. 
Ample low-level moisture and moderate instability is present to the
east of this activity, along with deep southerly low-level winds and
little inhibition.  This will result in rejuvenation of storms by
mid-afternoon along the remnant outflow boundary.  Forecast
soundings in this area show sufficient deep-layer shear for
supercell structures capable of large hail, damaging winds, and a
few tornadoes.  This activity will spread eastward through the
evening into LA/southern AR, with a continued risk of damaging wind
gusts and isolated tornadoes.

...OK/AR/MO...
The overnight MCS has significantly affected the air mass across
much of eastern OK/western AR/southern MO, with expansive cloud
cover and surface dewpoints now in the 50s to lower 60s.  Many of
the 12z models are insistent that higher theta-e air will return to
this region, resulting in a robust severe threat emerging by late
afternoon - but our confidence in that scenario is rather low at
this time.  Redevelopment of afternoon thunderstorms over eastern OK
seems likely, and there remains a risk of hail, damaging winds, and
a tornado or two from this activity.  Storms that form will spread
eastward into AR and southern MO during the evening.

$$


File: /opt/ldm/var/data/BY_SOURCE/KWNS/ACUS01/20240428T1945.txt



657 
ACUS01 KWNS 281626
SWODY1
SPC AC 281625

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
1125 AM CDT Sun Apr 28 2024

Valid 281630Z - 291200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
AND EVENING ACROSS PARTS OF EAST TEXAS...NORTHWEST LOUISIANA...AND
SOUTHWEST ARKANSAS....

...SUMMARY...
Clusters of severe storms are possible through early tonight, with
the most concentrated threat for wind damage, large hail and a few
tornadoes from the ArkLaTex southward into east Texas.

...East TX/LA/Southern AR...
A long-lived large nocturnal MCS that affected much of TX overnight
has weakened substantially, but remains over parts of east TX. 
Ample low-level moisture and moderate instability is present to the
east of this activity, along with deep southerly low-level winds and
little inhibition.  This will result in rejuvenation of storms by
mid-afternoon along the remnant outflow boundary.  Forecast
soundings in this area show sufficient deep-layer shear for
supercell structures capable of large hail, damaging winds, and a
few tornadoes.  This activity will spread eastward through the
evening into LA/southern AR, with a continued risk of damaging wind
gusts and isolated tornadoes.

...OK/AR/MO...
The overnight MCS has significantly affected the air mass across
much of eastern OK/western AR/southern MO, with expansive cloud
cover and surface dewpoints now in the 50s to lower 60s.  Many of
the 12z models are insistent that higher theta-e air will return to
this region, resulting in a robust severe threat emerging by late
afternoon - but our confidence in that scenario is rather low at
this time.  Redevelopment of afternoon thunderstorms over eastern OK
seems likely, and there remains a risk of hail, damaging winds, and
a tornado or two from this activity.  Storms that form will spread
eastward into AR and southern MO during the evening.

..Hart/Lyons.. 04/28/2024

$$


File: /opt/ldm/var/data/BY_SOURCE/KWNS/ACUS01/20240428T1626.txt



354 
ACUS01 KWNS 281242
SWODY1
SPC AC 281240

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0740 AM CDT Sun Apr 28 2024

Valid 281300Z - 291200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THROUGH EARLY
TONIGHT FROM THE ARKLATEX SOUTHWARD INTO EAST TX...

...SUMMARY...
Clusters of severe storms are possible through early tonight, with
the most concentrated threat for wind damage, large hail and a few
tornadoes from the ArkLaTex southward into east Texas.

...MO to east TX/western LA through tonight...
Within a larger-scale trough, a primary shortwave trough will move
northeastward from the central Plains to the upper MS Valley by
tonight. A weak surface cyclone will likewise move northeastward
from KS to IA, and an associated/weak cold front will drift
southeastward across KS/OK/northwest TX.

The warm sector has been altered substantially by an extensive
overnight QLCS that is weakening but continues to move eastward
across southern MO, western AR and northeast into south central TX. 
Widespread convective overturning has occurred across areas west of
the line, and many of the overnight forecast models appear too
aggressive with thermodynamic recovery today in its wake.  There may
be some recovery later today from eastern OK into MO in advance of
an embedded speed max rotating northeastward from west TX over
OK/MO.  However, destabilization is unlikely to be sufficient to
support more than SLGT-risk caliber severe probabilities.

Farther south, the remnant QLCS will encounter the richer
moisture/larger buoyancy in the undisturbed warm sector from the
ArkLaTex southward.  Vertical shear will be sufficient for
supercells, but the stronger shear and larger, curved hodographs
appear to be in response to warm advection within the modifying cold
pool that the models appear to remove a little too quickly today
from southeast OK/western AR northward.  Thus, the main threat for
any embedded supercells/tornadoes will be along the remnant outflow
from the ArkLaTex southward.  It appears possible that additional
storm development by this afternoon could evolve into another linear
cluster that will spread southeastward into southeast TX and western
LA by this evening/overnight with a continued threat for wind damage
and occasional large hail.

..Thompson/Leitman.. 04/28/2024

$$


File: /opt/ldm/var/data/BY_SOURCE/KWNS/ACUS01/20240428T1242.txt



836 
ACUS01 KWNS 280602
SWODY1
SPC AC 280600

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

$$


File: /opt/ldm/var/data/BY_SOURCE/KWNS/ACUS01/20240428T0602.txt



528 
ACUS01 KWNS 280104
SWODY1
SPC AC 280102

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0802 PM CDT Sat Apr 27 2024

Valid 280100Z - 281200Z

...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
NORTH TEXAS...OKLAHOMA...FAR SOUTHEAST KANSAS AND FAR SOUTHWEST
MISSOURI...

...SUMMARY...
Severe thunderstorms are expected this evening into tonight across
much of the southern Plains and lower Missouri Valley. The greatest
severe threat will be from north Texas northeastward through
Oklahoma into far southeast Kansas and southwest Missouri. All
hazards will be possible including tornadoes, with some strong,
damaging wind gusts above 70 mph, and very large hail exceeding 2
inches in diameter. Scattered severe storms will also be possible
later this evening in parts of west-central and southwest Texas.
Isolated severe storms are also expected to occur this evening in
parts of the mid to upper Mississippi Valley northeastward into the
Great Lakes.

...Southern Plains/Lower Missouri Valley...
An upper-level trough, evident on water vapor imagery, is
approaching the southern High Plains. An associated 60 to 80 knot
mid-level jet streak is currently ejecting northeastward into the
southern Plains. This feature has been slower than forecast, and
convective coverage across much of the southern Plains has been slow
to increase. The lack of convection across much of Oklahoma has
likely been a result of a capping inversion, that is evident on the
00Z Norman sounding just below 700 mb. As the mid-level jet streak
moves over the southern Plains this evening, this cap is expected to
weaken and the low-level jet will continue to strengthen. This
should result in a ramp up in convective coverage over the next 2 to
3 hours, with a line of strong to severe storms developing along the
western edge of the low-level jet from north Texas through central
and northeast Oklahoma into southwest Missouri.

The overall environment from north Texas into Oklahoma and southwest
Missouri is characterized by moderate instability (MLCAPE around
2500 J/kg), 0-6 km shear near 60 knots, and 700 to 500 mb lapse
rates from 8 to 8.5 C/km. This should continue to support the
development of supercells with large hail this evening. The more
intense supercells could produce hailstones greater than 2 inches in
diameter. In addition, the 00Z sounding from Norman has 0-3 km
storm-relative helicity around 400 m2/s2. This will also be
favorable for tornadoes. The tornado threat is expected to be
greatest with either supercells embedded in the line, or with
discrete cells ahead of the line. Strong tornadoes will be possible.
As the QLCS organizes this evening, tornadoes may also develop with
rotating elements within the line itself. This linear MCS is
expected to produce widespread wind damage and large hail from north
Texas into central and eastern Oklahoma, and west-central/southwest
Missouri. The severe threat will likely continue well into the
overnight period.

...Mid to Upper Mississippi Valley/Great Lakes...
The latest surface analysis shows a front from eastern Iowa
northeastward into the western Great Lakes. A moist airmass is
located to the southeast of the front, where surface dewpoints are
mostly from near 60 into the mid 60s F. The RAP is analyzing MLCAPE
in the 1000 to 2000 J/kg range, and moderate deep-layer shear across
much of this airmass near the front. The latest WSR-88D VWP from
Chicago has 0-6 km shear near 40 knots, and strong speed shear in
the low-levels. RAP forecast soundings this evening in the vicinity
also have steep lapse rates. This environment should support
supercell development with large hail. Wind damage will also be
possible with supercells and short bowing line segments.

..Broyles.. 04/28/2024

$$


File: /opt/ldm/var/data/BY_SOURCE/KWNS/ACUS01/20240428T0104.txt