SPC AC 240538
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1238 AM CDT Wed Apr 24 2024
Valid 241200Z - 251200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
WEST TEXAS THIS EVENING...
...SUMMARY...
Strong to severe thunderstorms will be possible today across parts
of Oklahoma and west Texas. Large hail and severe gusts will be the
primary hazards.
...Synopsis...
An upper ridge over the Rockies will shift east into the Plains
through tonight. However, guidance suggests subtle shortwave
impulses will migrate through the ridge during the late afternoon
into the evening/overnight. At the surface, strengthening lee
troughing is forecast across eastern NM near the TX border.
Meanwhile, a stationary boundary is forecast to extend across the TX
South Plains vicinity into southern/central OK, while a dryline
extends southward along the NM/TX border into southwest TX. Several
forecast models suggest a bulge in the dryline is possible across
far west TX where a weak surface low may develop. Overnight, the
stationary boundary is expected to lift northward as a warm front,
becoming located across the TX Panhandle into northern OK.
Further east, an upper trough will move across the Northeast states.
Boundary-layer moisture will remain limited, though midlevel
moisture will be plentiful. Cool temperatures aloft and modest
westerly flow will support isolated to scattered thunderstorms ahead
of an eastward-progressing cold front.
...OK - This Morning...
Thunderstorms are expected to develop early this morning across
central OK north of the stationary boundary in a warm advection
regime along the north edge of returning low-level moisture. This
activity is expected to be elevated. However, steep midlevel lapse
rates and increasing westerly mid/upper flow should be sufficient
for organized cells. Large hail will be possible with storms that
develop. However, coverage remains in question given expected height
rises through the morning hours as the upper ridge slowly shifts
east.
...West TX toward SW OK - This evening...
Capping will preclude convection for most of the day. However,
low-level moisture will increase with northwest extent on
southeasterly low-level flow, and low 60s F dewpoints are expected
into the Permian Basin and South Plains vicinity. Steep midlevel
lapse rates atop this moistening boundary-layer will foster moderate
instability from 1500-2500 J/kg. By late afternoon/early evening,
convection should begin to develop as inhibition weakens due to
increasing moisture and some indication of a weak impulse ejecting
east across the southern Rockies. Veering low-level wind profiles
become west/southwesterly aloft will result in favorable shear
profiles supporting supercells. Large hail to 2 inches in diameter
and gusts to 70 mph will be possible with storms that develop.
...Northern OK - Late Tonight...
As the stationary boundary lifts northward as a warm front
overnight, another round of warm advection thunderstorms will be
possible, this time from the eastern TX Panhandle into northern OK.
Forecast guidance varies considerably regarding coverage and
location of potential development, though the overall environment
(moderate elevated instability and modest shear) conditionally will
support hail.
...Northeast...
While boundary-layer moisture will remain poor today, cold
temperatures aloft will support weak instability. Deep-layer
westerly flow around 20-30 kt may support transient organized
cells/clusters by early afternoon. Meanwhile, heating ahead of the
cold front will allow for steepening low-level lapse rates. Gusty
winds to 40 mph will be possible with afternoon thunderstorms, but
overall severe potential appears too low for severe probabilities.
..Leitman/Weinman.. 04/24/2024
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z
SPC AC 240600
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
0100 AM CDT Wed Apr 24 2024
Valid 251200Z - 261200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM THE
EASTERN TX PANHANDLE AND WESTERN OK INTO SOUTHWEST/SOUTH-CENTRAL
KS...
...SUMMARY...
Scattered severe thunderstorms are expected from late Thursday
afternoon into Thursday night across parts of the central and
southern Great Plains. Very large hail, severe wind gusts, and a
couple strong tornadoes will all be possible.
...Synopsis...
A shortwave trough initially over the Southwest is still forecast to
take on an increasingly negative tilt as it moves eastward towards
the central/southern Plains by Thursday night into Friday morning.
In response, a deepening surface low will move from the central High
Plains toward northwest KS/southwest NE by late Thursday night into
Friday morning. A surface boundary will move northward as a warm
front across the central Plains through the day, though convective
outflow may limit its progress across parts of central/western KS.
Along/south of the warm front, relatively rich low-level moisture
will stream northward to the east of a dryline that will become
established from the eastern TX Panhandle into western KS and
eastern CO.
...Southern/central Great Plains...
Potential for a few intense supercells remains evident across
western KS into western OK and the OK/TX Panhandles, with a threat
for very large hail, severe wind gusts, and possibly a couple of
strong tornadoes. Isolated supercells will also be possible into
parts of northwest KS, southwest NE, and northeast CO. Some
overnight severe potential also remains evident farther east into
central KS/OK and north TX.
Substantial convection may be ongoing at the start of the period
across parts of eastern KS/OK. While this convection will likely
remain elevated, some threat for hail and isolated damaging gusts
cannot be ruled out through much of the day.This convection may
persist through much of the day, driven by persistent low-level warm
advection to the cool side of the effective outflow. Should this
occur, outflow may tend to spread westward through the day,
providing a limit to the eastward extent of higher-end severe
potential.
Otherwise, a favorable conditional supercell environment is still
expected to develop along/ahead of the dryline from western KS/OK
into the OK/TX Panhandles, as low-level and deep-layer shear
increase across a moderately to strongly unstable environment. While
stronger ascent may not arrive across a broader portion of the
central/southern Great Plains until evening, isolated supercell
development will be possible by late afternoon.
Steep midlevel lapse rates will support an initial threat of very
large hail. The tornado threat will also increase with any supercell
that persists into the evening, with low-level shear/SRH expected to
increase with time and eastward extent, and any longer-lived
supercells could pose a strong tornado threat. Uncertainty remains
regarding the number of supercells that develop, and the longevity
of any such cells into the evening given that outflow may begin
impinging on the warm sector from the east.
Another round of potentially severe storms may develop late Thursday
night into Friday morning along the Pacific front/dryline. Moderate
instability and strong deep-layer shear will support organized
convection with this activity, which may tend to become linear with
time. The overnight storms could pose some threat for all severe
hazards, though the magnitude of the threat remains uncertain due to
lingering near-surface stability and the unfavorable time of day.
...Parts of the central/northern High Plains...
Near/north of the deepening surface, relatively moist low-level
southeasterly flow beneath steep midlevel lapse rates will support
increasing instability through the day. Favorable deep-layer shear
will support isolated supercell potential by mid/late afternoon
across northeast CO and adjacent portions of southwest NE and
northwest KS. Very large hail (potentially 2-2.5 inches in diameter)
will likely be the primary threat, though cells in the vicinity of
the effective warm front will also be capable of producing a tornado
or two.
Farther north, moderate buoyancy will support scattered diurnal
thunderstorm development into the Black Hills vicinity. Deep-layer
shear will be weaker in this area, but may still be sufficient for
modestly organized storms capable of large hail.
..Dean.. 04/24/2024
WUUS02 PTSDY2
SPC AC 231831
Day 3 Convective Outlook AMEND 1
NWS Storm Prediction Center Norman OK
0131 PM CDT Tue Apr 23 2024
Valid 251200Z - 261200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM THE
EASTERN TX PANHANDLE AND WESTERN OK INTO SOUTHWEST/SOUTH-CENTRAL
KS...
AMENDED TO UPDATE FORECAST
...SUMMARY...
Severe thunderstorms are likely from late Thursday afternoon into
Thursday night across parts of the central and southern Great
Plains. Very large hail, severe wind gusts, and strong tornadoes
will all be possible.
Guidance continues to suggest strong buoyancy will be in place ahead
of a negatively tilted shortwave trough ejecting across the southern
High Plains. General forecast expressed in the previous outlook
remains valid, but confidence in an area of greater severe-weather
potential has become more apparent with the most recent guidance.
Late afternoon development is anticipated across the TX Panhandle,
with these storms quickly becoming severe and capable of large to
very large hail up to 3" in diameter. Low-level moisture may be
later to arrive in west-central/southwest KS, delaying convective
initiation to a few hours later than farther south. Large to very
large hail is anticipated with initial development across
west-central/southwest KS as well.
In both of these areas, storms are expected to move
east-northeastward off the dryline, encountering strengthening
low-level southerly flow and environment that is increasingly
favorable for tornadoes. Low-level shear will continue to
strengthening into the early evening, and the overall environment
supports the potential for strong to intense tornadoes if a discrete
mode can be maintained.
--- Previous Discussion issued at 0230 AM CDT Tue Apr 23 2024 ---
...Synopsis...
A shortwave trough initially over the Southwest is forecast to take
on an increasingly negative tilt as it moves eastward towards the
central/southern Plains by Thursday night into Friday morning. In
response, a surface low will consolidate and deepen across the
central High Plains through the day, before moving northeastward
toward northwest KS/southwest NE by Friday morning. An initially
stationary surface boundary will move northward as a warm front
across the central Plains through the day. Along/south of the warm
front, relatively rich low-level moisture will stream northward to
the east of a dryline that will become established from the eastern
TX Panhandle into western KS and eastern CO.
...Southern/central Great Plains...
Coverage of the severe-thunderstorm threat remains somewhat
uncertain, but a couple intense supercells are possible by Thursday
evening near the dryline from western KS into western OK and the
TX/OK Panhandles. Another round of overnight convection will
potentially bring the severe threat eastward into a larger portion
of the central/southern Plains.
The warm sector of the deepening cyclone will likely remain capped
for much of the day, though elevated convection may persist from
parts of central/eastern KS into eastern OK, to the north of the
effective warm front. Increasing moisture beneath steep midlevel
lapse rates will support MLCAPE in excess of 2000 J/kg along/east of
the dryline, as deep-layer shear strengthens across the region
through the day.
Ascent attendant to the approaching shortwave trough will begin to
impinge upon the warm sector by late afternoon, with isolated
supercell development possible near the surface low across southwest
KS and southward down the dryline into the TX Panhandle. Very large
hail (potentially 2-3 inches in diameter) will likely be the primary
initial hazard. A notable increase in low-level flow/shear near and
after 00Z will also support a tornado threat with any supercells
that can persist into the evening across parts of western KS/OK.
While any initial dryline storms may weaken by mid/late evening due
to increasing MLCINH with eastward extent, renewed storm development
is possible overnight along the Pacific cold front from southwest TX
into western/central KS/OK as stronger large-scale ascent
overspreads the region. Steep midlevel lapse rates, moderate
buoyancy, and strong low-level and deep-layer shear will
conditionally support a severe threat with overnight convection
across the warm sector, though storm mode may become complex and
tend toward a linear evolution with time. Severe wind gusts may
become an increasing threat with the nocturnal convection, though
hail and a couple tornadoes will also be possible if semi-discrete
or embedded supercells can be maintained.
...NE/WY border region into northeast CO...
Low-level southeasterly flow will support modest moisture return
into parts of northeast CO, southeast WY, and western NE, to the
north of the deepening cyclone. Thunderstorm development will be
possible near and to the cool side of the effective warm front
during the afternoon. While deep-layer shear will be weaker compared
to areas farther southeast, steep midlevel lapse rates will support
an isolated hail threat. A tornado also cannot be ruled out, if
surface-based storms can be maintained within this regime.
..Mosier.. 04/23/2024
WUUS03 PTSDY3
NOTE: THE NEXT DAY 3 OUTLOOK IS SCHEDULED BY 0730Z
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