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 240730
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0230 AM CDT Wed Apr 24 2024
Valid 261200Z - 271200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE
CENTRAL/SOUTHERN GREAT PLAINS INTO THE MID MISSISSIPPI VALLEY AND
OZARKS...
...SUMMARY...
An active severe weather day appears possible on Friday from parts
of Nebraska and Iowa southward into parts of the southern Great
Plains and Ozarks. A few tornadoes, large to very large hail, and
damaging winds will all be possible.
...Synopsis...
A negatively tilted mid/upper-level shortwave trough and associated
occluding surface low are forecast to move northeastward toward the
upper Great Lakes from Friday into Friday night. A trailing Pacific
front/dryline will move eastward through the day across the
central/southern Plains, before retreating westward Friday night. A
warm front will move northward in advance of the surface low across
MO into parts of IA, though its progress may be slowed by convective
outflow resulting from extensive D2/Thursday convection.
...Central/southern Plains into the mid MS Valley...
A relatively active severe weather day appears possible from eastern
portions of the Great Plains into parts of the mid MS Valley and
Ozarks on Friday. However, uncertainty remains regarding the impact
of extensive antecedent convection on the quality of the warm
sector.
Thunderstorms that develop late on D2/Thursday may be ongoing during
the morning from eastern KS into central/eastern OK and north TX. At
least some severe threat may persist through the morning with this
convection, as it spreads into parts of MO/AR. With favorable
deep-layer shear across the warm sector, some intensification of
early convection will be possible during the afternoon, though there
may be a tendency for storms to move eastward out of the primary
instability axis. The strongest storms across eastern portions of
the warm sector could pose at least some threat for all severe
hazards, though magnitude of the threat remains uncertain.
With the dryline not expected to make a strong eastward push, some
redevelopment cannot be ruled out later in the day. Depending on
heating and destabilization trends, supercell development will be
possible from eastern NE/western IA southward into the ArkLaTex
region. Large hail (potentially in excess of 2 inches in diameter)
and could accompany any supercell development in this area, given
the persistence of rich low-level moisture beneath steep midlevel
lapse rates. Persistent moderate to strong low-level flow/shear will
also support tornado potential, especially if supercells can be
sustained near the ejecting shortwave and surface low across
northern portions of the risk area.
Southwestward extent of the severe threat during the
afternoon/evening remains uncertain. Development cannot be entirely
ruled out from central OK into north/central TX along the nearly
stalled dryline, though coverage would likely remain very isolated
in the wake of the departing shortwave trough.
..Dean.. 04/24/2024
WUUS03 PTSDY3
NOTE: THE NEXT DAY 3 OUTLOOK IS SCHEDULED BY 0730Z
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