553
ACUS02 KWNS 220602
SWODY2
SPC AC 220601

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
0101 AM CDT Wed May 22 2024

Valid 231200Z - 241200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
THE GREAT PLAINS INTO THE MID-SOUTH...

...SUMMARY...
Severe thunderstorms are possible across portions of the
central/southern Plains into the Mid-South region on Thursday.
Damaging gusts, hail and a couple of tornadoes will be possible.
Isolated strong to severe thunderstorms also will be possible across
across the Ohio and Tennessee Valleys into the Mid-Atlantic and
Northeast.

...Synopsis...

Enhanced west/southwesterly flow will spread across the southern
Plains to the Lower MS Valley and Mid-Atlantic vicinity on Thursday.
One upper shortwave impulse is forecast to eject from the southern
Rockies to the Mid-South, while another subtle impulse moves from
the TN Valley vicinity to the Carolinas. To the north, a negatively
tilted compact upper shortwave trough is expected to pivot east from
the northern Great Basin/Rockies to the northern Plains. This will
bring a small but strong 500 mb jet of 70-80 over NE/SD during the
evening/overnight. Meanwhile, an upper low and attendant trough
migrating east across Ontario and Quebec will result in height falls
over the Northeast.

At the surface, a cold front is expected to shift east across the
Northeast states through early evening. To the west across the
northern Plains vicinity, lee low development over the
northern/central High Plains will result in increasing southerly
low-level flow across the Plains. This will aid in northward
transport of Gulf moisture, and surface dewpoints are expected to
increase markedly across the southern/central Plains east into the
OH/TN valleys. A surface dryline is forecast to extend southward
from a low in western KS into central TX. Meanwhile, a cold front
will sweep east/southeast across the northern/central Plains, and
into northwest OK during the evening/overnight hours.

...Southern Plains/KS to the Mid-South Vicinity...

A very moist airmass will develop by midday, with surface dewpoints
in the upper 60s to near 70 F common. Steep midlevel lapse rates
atop this very moist boundary layer will foster strong to extreme
instability with MLCAPE from 2500-4500 J/kg evident in forecast
soundings. Thunderstorms may develop across parts of AR into the
Mid-South vicinity by early afternoon in a strong warm advection
regime as a warm front rapidly lifts northward. Low-level shear is
expected to be fairly weak, but supercell wind profiles are depicted
in forecast soundings. This will support storms capable of large
hail and damaging gusts.

Further west, at least isolated convection is expected to develop
along the dryline from west-central KS to near the OK/TX border.
Capping may limit coverage given modest large-scale ascent. However,
given the degree of instability, robust updrafts should be able to
overcome modest capping. Very large hail (near 2.5 inch diameter)
will be possible with these storms in addition to strong gusts. By
late afternoon/early evening, low-level shear is expected to
increase, resulting in enlarged low-level hodographs. A few
tornadoes will be possible with any sustained supercell activity.
Some potential for upscale growth into an MCS will exist from
southeast KS/southwest MO into eastern OK/AR as the low-level jet
increases and via storm outflow consolidation.

...Northern/Central Plains...

Thunderstorms are expected to develop in the vicinity of the
deepening surface low over the Dakotas southward along the
east/southeast-progressing cold front. Low-level moisture will
remain modest with northward extent across the Dakotas into western
MN, with higher-quality moisture expected over NE. However, steep
midlevel lapse rates will be present, and contribute to 1000-2000
J/kg MLCAPE. Strong to severe storms producing hail will be possible
initially. Damaging wind potential may increase toward
evening/overnight as a line of convection develops amid strong
frontal forcing.

...KY/TN to the Mid-Atlantic...

A subtle shortwave trough will spread east across the region as
boundary-layer moisture increasing amid strengthening southerly
low-level flow. Clusters of thunderstorms may pose a risk of hail
and gusty winds across parts of KY/TN. With eastward extent into VA
and the Carolinas, thunderstorm coverage will be higher. Clusters of
storms may develop into one or more east/southeast progressing
bands. Deeply-mixed sub-cloud thermodynamic profiles suggest strong
gusts will be possible in addition to isolated hail.

...Northeast...

A surface cold front will shift east across the region during the
day before moving offshore by early evening. Surface dewpoints in
the low 60s and steep midlevel lapse rates will support MLCAPE
values around 1000-2000 J/kg. Low-level flow will remain weak, but
fast mid/upper westerly flow will support elongated/straight
hodographs. Thunderstorms may produce isolated strong gusts and
marginally severe hail in this environment.

..Leitman.. 05/22/2024

$$