ACUS02 KWNS 191732
SWODY2
SPC AC 191730

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1230 PM CDT Wed Jul 19 2023

Valid 201200Z - 211200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE SOUTHERN/CENTRAL HIGH PLAINS...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE GREAT LAKES/OHIO VALLEY...AND THE CAROLINAS...

...SUMMARY...
Scattered severe thunderstorms should occur Thursday across parts of
the central/southern High Plains, Great Lakes/Ohio Valley, and parts
of the Carolinas. The greatest concentration of severe wind may
occur over parts of southeastern Colorado into southwestern Kansas
and the Oklahoma Panhandle.

...Central/Southern High Plains...
The western portion of a cold front will likely stall and become
draped across eastern CO during the day. Easterly low-level flow
will again favor seasonably moist conditions across the central High
Plains with thunderstorm development expected by midday into the
early afternoon along/near the CO Front Range. Convection should
move east of the higher terrain during the early/mid afternoon and
gradually intensify. Various model guidance shows elongated
hodographs which will be favorable for organized thunderstorms,
including supercells early in the convective life cycle. Large hail
should be the main severe threat initially. Increasing coverage late
Thursday afternoon/evening will likely favor a cluster/MCS to
develop and potentially track east-southeastward near the boundary
across southeastern CO/southwestern KS and perhaps into the OK/TX
Panhandles during the evening, with a wind threat perhaps continuing
into the late night near the OK/KS border. Given increased
confidence in this MCS scenario occurring, have added greater severe
wind probabilities and an Enhanced Risk.

...Great Lakes/Ohio Valley...
Although details remain uncertain, isolated to scattered
showers/thunderstorms may be ongoing across parts of KY/TN Thursday
morning in association with enhanced mid-level westerly flow moving
across this area. Still, a moist low-level airmass will destabilize
where cloud breaks occur ahead of a southeastward-moving front.
Various NAM/RAP forecast soundings across the Great Lakes and Ohio
Valley ahead of the front show potential for organized storms given
adequate instability and deep-layer shear. The more intense
convection will be capable of scattered severe/damaging winds, in
addition to the possibility of large hail and a tornado with any
supercells. Overall thunderstorm coverage will probably be greatest
over the OH Valley in association with the eastward-moving upper
trough, with weaker low-level convergence potentially limiting
coverage over mid the MS Valley into the Ozarks. Have expanded the
Slight Risk across parts of Lower MI and into northwestern PA and
vicinity, where latest guidance shows sufficient destabilization
should occur to support surface-based thunderstorms and increased
potential for severe hail/damaging winds.

...Carolinas...
Strong heating of a moist airmass ahead of a lead disturbance will
promote moderate to strong instability by early Thursday afternoon.
Modest ascent should aid in the development of scattered storms by
mid to late afternoon. Damaging gusts with the more organized
multicells should be the primary concern, especially if a belt of
stronger 2-4 km flow (30-40+ kt) is realized. This activity will
likely weaken by Thursday evening.

..Gleason.. 07/19/2023

$$
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ACUS02 KWNS 251720
SWODY2
SPC AC 251719

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1219 PM CDT Tue Jul 25 2023

Valid 261200Z - 271200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS SOUTHERN
LOWER MICHIGAN INTO NORTHERN INDIANA AND NORTHWEST OHIO...

...SUMMARY...
Scattered severe thunderstorms are expected across parts of Lower
Michigan into northern Indiana/Ohio Wednesday afternoon and evening.
Damaging gusts and a couple of tornadoes are possible with this
activity.

...Great Lakes Vicinity...

A compact but potent midlevel shortwave trough will shift east from
the MN/WI/IA border to western PA/NY on Wednesday. This will bring a
belt of enhanced westerly mid/upper flow focused on southern Lower
MI into northern IN/OH. At the surface, mid/upper 60s to near 70 F
dewpoints are forecast ahead of an eastward developing surface low
and cold front. Meanwhile, a warm front will be draped across
southern or central Lower MI.

Early morning showers and cloudiness are expected across parts of
the Mid-MS Valley into the Great Lakes vicinity. This activity will
result in lingering boundary-layer inhibition until afternoon when
stronger large-scale ascent and continued warm advection erode
capping. By mid/late afternoon, a tongue of 1500-3000 J/kg MLCAPE
will support vigorous thunderstorm development near the surface
low/triple point across southwest Lower MI and northern IN.
Effective shear magnitudes near 35+ kt will support initial
supercells. As convection develops eastward through the
afternoon/evening some upscale development is possible given only
modest directional shear and moderate/strong deep-layer westerly
flow. Steep low and midlevel lapse rates amid strong instability
will support damaging gust potential, while a more isolated hail
risk will accompany any more discrete convection. Within the warm
frontal zone and near the surface low, backed low-level flow will
maximize low-level shear and forecast soundings indicate enlarged,
favorably curved hodographs. A few tornadoes will be possible near
this zone across southern Lower MI into far northern IN/OH.

The severe risk is expected to remain relatively confined to
portions of Lower MI into northern IN/OH as any morning convection
further west is expected to be weak/sub-severe and stronger forcing
will remain focused further north across the Great Lakes. As a
result the western and southern periphery of the Marginal and Slight
risk areas have been trimmed across the Mid-MS/Lower OH Valley
vicinity compared to the previous Day 2 outlook.

...Dakotas into the central High Plains...

A surface trough will extend south from a surface low over
south-central Canada and through the north-central Great Plains. A
relatively moist airmass east of the wind shift will feature
dewpoints in the 60s with 50s expected in parts of the central High
Plains. Strong heating will steepen low-level lapse rates. Isolated
severe hail/wind are possible with the stronger storms. This
activity will likely dissipate during the evening.

If trends toward higher convective coverage increase across parts of
ND into northwest MN, an upgrade to Slight risk may be needed in
subsequent outlooks.

..Leitman.. 07/25/2023

$$
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ACUS02 KWNS 060601
SWODY2
SPC AC 060600

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
0100 AM CDT Sun Aug 06 2023

Valid 071200Z - 081200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF THE CENTRAL/SOUTHERN APPALACHIANS AND THE MID-ATLANTIC STATES...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SEPARATELY ACROSS
THE CENTRAL HIGH PLAINS...

...SUMMARY...
Severe thunderstorms are possible Monday across portions of the
southern Appalachians, mid-Atlantic and northeast U.S. Scattered
swaths of damaging gusts are expected with this activity. Additional
widely scattered thunderstorms are possible across the central High
Plains, posing a risk for large hail and damaging gusts.

...Synopsis...

A potent mid/upper shortwave trough this time of year will shift
east from the Mid-MS Valley to the Appalachians on Monday. This will
bring a band of anomalously strong west/southwesterly flow to the
region, with the strongest flow focused from southern PA southward
to northern GA and the Carolinas vicinity. At the surface, low
pressure will shift east from northern IL into northern OH through
evening, before lifting northeast across the lower Great Lakes
overnight. A cold front attendant to the surface low will sweep
east/southeast across the Midwest, and become positioned from
western NY/PA into northern AL/MS by Tuesday morning. Mid 60s to mid
70s F surface dewpoints are forecast across the large warm sector
ahead of the cold front and ejecting mid/upper trough.

...OH Valley to Mid-Atlantic...

Some areas of showers and cloudiness are possible early in the day
across parts of the Mid-Atlantic vicinity in association with an
ejecting lead shortwave impulse, continued warm advection and backed
low-level flow to the east of a lee surface trough should keep the
atmosphere primed for severe thunderstorm potential during the afternoon/evening.

Convection is expected to develop by midday closer to the surface
front over parts of OH/KY. Multiple bands of convection are then
expected into the afternoon with eastward extent into WV/southern PA
and the Delmarva. A mix of semi-discrete cells and clusters are
possible initially. A risk for all severe hazards is expected given
effective shear greater than 40 kt, effective SRH greater than 200
m2/s2 and MLCAPE 1500-3000 J/kg. With time, upscale growth into a
bowing MCS is possible across parts of southern PA/WV and into the
Delmarva vicinity, posing an Enhanced risk (level 3 of 5) for
severe/damaging gusts during the afternoon/evening.

Instability will weaken with northward extent into NY and southern
New England. However, isolated strong/severe storms posing a risk
mainly for strong gusts and perhaps small hail are expected.

...TN Valley to the Carolinas/Southeast vicinity...

Thunderstorm clusters are expected to develop from Middle/eastern TN
into northern AL/GA by early afternoon. Strong instability with
MLCAPE values generally from 2000-4000 J/kg and effective shear
magnitudes greater than 40 kt will support vigorous updrafts.
Further south from the surface low, deep-layer flow (above 1 km)
will generally be unidirectional from the west. Some modest backed
low-level flow is forecast, which could support a tornado or two,
but convection is expected to grow upscale into a bowing MCS fairly
quickly as storms spread east across eastern TN/northern GA and the
Carolinas during the afternoon/evening. Convection should gradually
weaken as it approaches the coastal Carolinas after dark.

Some uncertainty exists with regards to severe potential with
southward extent. Deep-layer flow weakens with southward extent, but
if southward propagating cluster develops, some wind risk can be
expected into southern AL/GA given degree of instability and a very
moist airmass/water-loaded downdrafts.

...Central High Plains...

Moderate mid/upper northwesterly flow will continue to stream across
the central High Plains vicinity on Monday. Moderately cool 500 mb
temps around -10 C will support steep midlevel lapse rates. Modest
boundary layer moisture is forecast along a surface trough, with
dewpoints generally in the 50s, supporting moderate instability.
Strong vertical shear (effective shear greater than 45 kt) will
foster organized updrafts, while elongated/straight hodographs
suggest large hail will be possible. A deeply-mixed boundary-layer
with dewpoint depressions around 20 F also may foster strong gust
potential. While the boundary-layer will be somewhat on the dry
side, backed low-level winds in the vicinity of a weak surface low
over northeast CO/NE Panhandle could support a brief tornado in
addition to the wind/hail risk.

...Northeast TX toward the Lower MS Valley...

A surface boundary is forecast to extend west to east across the
region. Differential heating along the boundary, and a very
moist/unstable airmass will support isolated thunderstorm
development. Vertical shear will be rather weak, but isolated strong
gusts may accompany thunderstorms during the afternoon. Isolated coverage/longevity of this activity preclude higher risk
probabilities at this time.

..Leitman.. 08/06/2023

$$
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