Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0253 PM CDT Sat Aug 31 2024

Valid 312000Z - 011200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
THE CENTRAL APPALACHIANS AND UPPER OHIO VALLEY...

...SUMMARY...
Severe thunderstorms capable of producing mainly damaging winds
remain possible this afternoon and evening from parts of the central
Appalachians into the Ohio and Tennessee Valleys. Isolated severe
wind gusts may also occur across parts of the northern Great Lakes.

...20Z Update...
Some minor adjustments have been made to the Marginal and Slight
Risks based on observational trends, but no major changes have been
made to the outlook. Scattered damaging winds remain possible
through late afternoon and perhaps into early evening from parts of
WV into western/central PA and western MD/VA. See MCD 2040 regarding
the short-term threat in this area. Also, see the previous
discussion below for more information.

..Dean.. 08/31/2024

.PREV DISCUSSION... /ISSUED 1129 AM CDT Sat Aug 31 2024/

...Mid-Atlantic into the Ohio and Tennessee Valleys...
A mid/upper-level trough will move eastward across Ontario/Quebec
and the Great Lakes today while undergoing some amplification. 
Ahead of this feature, a surface front will move eastward over parts
of the Northeast/Mid-Atlantic, and southeastward over the OH Valley
before eventually stalling. A warm front will lift north through the
period across the mid-Atlantic and northeast states.  Late morning
visible satellite imagery shows substantial low cloud cover over
much of the Northeast and Mid-Atlantic. This will reduce daytime
heating and delay destabilization, especially east of the Blue Ridge
Mountains. However, with a moist low-level air mass in place, even
modest diurnal heating will result in sufficient destabilization to
support some risk for strong/severe storms.

The stronger mid-level flow associated with the upper trough is
expected to remain generally displaced to the north/west of the
surface warm sector. Even so, modestly increasing west-southwesterly
winds with height through mid levels should support around 20-30 kt
of deep-layer shear across parts of the central Appalachians and
upper OH Valley vicinity. This shear will be sufficient for loosely
organized multicell clusters to develop or intensify and
subsequently spread east-southeastward through this afternoon.
Isolated to scattered damaging winds should be the main threat with
this convection, although some hail may also occur with the
strongest cells. Storms should gradually weaken with eastward extent
by this evening across the Mid-Atlantic while encountering a less
unstable air mass.  Weaker deep-layer shear with southward extent
into the lower OH Valley and TN Valley will likely limit overall
thunderstorm organization.  However, occasional damaging winds may
still occur with thunderstorms along/south of the front as low-level
lapse rates steepen.

...Northern Great Lakes...
Strong west-northwesterly mid-level flow will exist over
the Upper Midwest and northern Great Lakes in association with a
shortwave trough embedded within a broader cyclonic flow.  While
low-level moisture and related instability are both expected to
remain limited, large-scale ascent and strong deep-layer shear may
support the development of low-topped thunderstorms this afternoon.
If these thunderstorms can be sustained, then isolated strong to
severe winds may occur given the forecast strength of the low to
mid-level flow in the presence of steepened low-level lapse rates.

Day 3 Convective Outlook  
NWS Storm Prediction Center Norman OK
0159 PM CDT Sat Aug 31 2024

Valid 021200Z - 031200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorm potential remains quite limited across the U.S.
on Monday.

...Synopsis...
Upper ridging will build over much of the central CONUS as a
mid-level trough ejects into the Atlantic, and a second mid-level
trough traverses the Pacific Northwest on Day 3/Monday. WAA, driven
by surface lee troughing across the Plains, as well as the heating
of a moist boundary layer across the southeast quadrant of the U.S.,
will foster isolated to scattered thunderstorm development from
eastern NM to the central/southern Atlantic Seaboard. At least
isolated thunderstorm development is also likely across much of the
Interior West as the West Coast mid-level trough approaches.

...Pacific Northwest...
Isolated to scattered thunderstorms may form near a weak surface low
to the lee of the Cascades late Monday afternoon into early evening.
These storms should be high based as they develop atop a boundary
layer that may mix up to 600-500 mb. Steep low and mid-level lapse
rates exceeding 9 C/km amid stronger unidirectional southwesterly
flow above 500 mb (hence elongated hodographs) may encourage storm
organization to some degree, with gusty winds possible. A Category
1/Marginal Risk for severe gusts may be needed over the Harney Basin
in eastern OR in future outlooks if greater storm coverage by
afternoon peak heating becomes apparent.

..Squitieri.. 08/31/2024

Day 2 Convective Outlook  
NWS Storm Prediction Center Norman OK
1217 PM CDT Sat Aug 31 2024

Valid 011200Z - 021200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
SOUTHERN NEW ENGLAND INTO THE SOUTHERN APPALACHIANS...

...SUMMARY...
Strong thunderstorms capable of producing damaging gusts still
appear possible from southern New England into the southern
Appalachians on Sunday.

...Synopsis...
A mid-level trough will progress across the northeastern U.S. as an
upper ridge builds across the Plains and a second mid-level trough
impinges on the West Coast tomorrow (Sunday). A surface cold front
accompanying the eastern upper trough will sweep across much of the
central, northern U.S. east of the Rockies through the period,
serving as a lifting mechanism for at least scattered thunderstorms
from New England down to the Southern Plains. The best chance for
isolated strong to perhaps severe thunderstorms will be from
southern New England into the central Appalachians, where modest
mid-level flow will overspread a mixing boundary layer by afternoon.


...Southern New England into the central Appalachians...
At least scattered clusters of thunderstorms should develop ahead of
the cold front from southern New England into the central
Appalachians by late morning or early afternoon, when convective
temperatures in the mid 80s F are reached. With surface dewpoints in
the mid 60s to just over 70 F, MLCAPE will exceed 1000 J/kg in most
spots, with parts of the Carolinas seeing up to 2000 J/kg MLCAPE,
driven primarily by low-level lapse rates. Stronger mid-level flow
and accompanying vertical wind shear is expected to lag the surface
cold front, with effective bulk shear values likely remaining under
30 kts over most locales. As such, pulse-cellular and perhaps
briefly multicellular convection will be the dominant storm modes.
Given a heated, mixed boundary layer, storms from southern New
England into the central Appalachians may produce a few strong,
damaging wind gusts.

..Squitieri.. 08/31/2024

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
1129 AM CDT Sat Aug 31 2024

Valid 311630Z - 011200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
THE CENTRAL APPALACHIANS AND UPPER OHIO VALLEY...

...SUMMARY...
Severe thunderstorms capable of producing mainly damaging winds will
be possible today from parts of the central Appalachians into the
Ohio and Tennessee Valleys. Isolated severe wind gusts may also
occur across parts of the northern Great Lakes.

...Mid-Atlantic into the Ohio and Tennessee Valleys...
A mid/upper-level trough will move eastward across Ontario/Quebec
and the Great Lakes today while undergoing some amplification. 
Ahead of this feature, a surface front will move eastward over parts
of the Northeast/Mid-Atlantic, and southeastward over the OH Valley
before eventually stalling. A warm front will lift north through the
period across the mid-Atlantic and northeast states.  Late morning
visible satellite imagery shows substantial low cloud cover over
much of the Northeast and Mid-Atlantic. This will reduce daytime
heating and delay destabilization, especially east of the Blue Ridge
Mountains. However, with a moist low-level air mass in place, even
modest diurnal heating will result in sufficient destabilization to
support some risk for strong/severe storms.

The stronger mid-level flow associated with the upper trough is
expected to remain generally displaced to the north/west of the
surface warm sector. Even so, modestly increasing west-southwesterly
winds with height through mid levels should support around 20-30 kt
of deep-layer shear across parts of the central Appalachians and
upper OH Valley vicinity. This shear will be sufficient for loosely
organized multicell clusters to develop or intensify and
subsequently spread east-southeastward through this afternoon.
Isolated to scattered damaging winds should be the main threat with
this convection, although some hail may also occur with the
strongest cells. Storms should gradually weaken with eastward extent
by this evening across the Mid-Atlantic while encountering a less
unstable air mass.  Weaker deep-layer shear with southward extent
into the lower OH Valley and TN Valley will likely limit overall
thunderstorm organization.  However, occasional damaging winds may
still occur with thunderstorms along/south of the front as low-level
lapse rates steepen.

...Northern Great Lakes...
Strong west-northwesterly mid-level flow will exist over
the Upper Midwest and northern Great Lakes in association with a
shortwave trough embedded within a broader cyclonic flow.  While
low-level moisture and related instability are both expected to
remain limited, large-scale ascent and strong deep-layer shear may
support the development of low-topped thunderstorms this afternoon.
If these thunderstorms can be sustained, then isolated strong to
severe winds may occur given the forecast strength of the low to
mid-level flow in the presence of steepened low-level lapse rates.

..Bunting/Jewell.. 08/31/2024

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0740 AM CDT Sat Aug 31 2024

Valid 311300Z - 011200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CENTRAL APPALACHIANS AND UPPER OHIO VALLEY...

...SUMMARY...
Severe thunderstorms capable of producing mainly damaging winds will
be possible today from parts of the central Appalachians into the
Ohio and Tennessee Valleys. Isolated severe wind gusts may also
occur across parts of the northern Great Lakes.

...Mid-Atlantic into the Ohio and Tennessee Valleys...
A mid/upper-level trough will make slow eastward progress today
across Ontario/Quebec and the Great Lakes while amplifying further.
Ahead of this feature, a surface front should continue to lose
definition and weaken through the day as it moves eastward over
parts of the Northeast/Mid-Atlantic, and southeastward over the OH
Valley before eventually stalling. Recent visible satellite imagery
shows cloud cover remains prevalent over much of the Northeast and
Mid-Atlantic. This will hinder daytime heating and delay
destabilization, especially east of the Blue Ridge Mountains. Still,
area 12Z soundings and recent surface observations indicate a moist
low-level airmass remains in place ahead of the weak cold front.
Generally less cloud cover with westward and southward extent into
the upper OH Valley and TN Valley should allow for greater
instability to develop this afternoon across these regions.

The stronger mid-level flow associated the upper trough is expected
to remain generally displaced to the north/west of the surface warm
sector. Even so, modestly increasing west-southwesterly winds with
height through mid levels should support around 20-30 kt of
deep-layer shear across parts of the central Appalachians and upper
OH Valley vicinity. This shear will be sufficient for loosely
organized multicell clusters to develop and subsequently spread
east-southeastward through this afternoon. Isolated to scattered
damaging winds should be the main threat with this convection,
although some hail may also occur with the strongest cores. Activity
should weaken with eastward extent late this afternoon and evening
across the Mid-Atlantic as it encounters a less unstable airmass.
Weaker deep-layer shear with southward extent into the lower OH
Valley and TN Valley will likely limit overall thunderstorm
organization. But, occasional damaging winds may still occur with
thunderstorms along/south of the front as low-level lapse rates
steepen with diurnal heating.

...Northern Great Lakes...
Strong west-northwesterly mid-level flow will be present today over
the Upper Midwest and northern Great Lakes, in association with a
shortwave trough embedded within a larger upper trough moving
east-southeastward across these regions. While low-level moisture
and related instability are both expected to remain limited,
large-scale ascent and strong deep-layer shear may support the
development low-topped convection this afternoon. If these
thunderstorms can form and be sustained, then isolated strong to
severe winds may occur given the forecast strength of the low to
mid-level flow amid steepened low-level lapse rates.

..Gleason/Leitman.. 08/31/2024

Day 4-8 Convective Outlook  
NWS Storm Prediction Center Norman OK
0333 AM CDT Sat Aug 31 2024

Valid 031200Z - 081200Z

...DISCUSSION...
Global models are in reasonable agreement with handling of
large-scale features through about Day 5/Wednesday, after which
divergent tendencies become apparent -- particularly with the
handling of a weak short-wave feature moving across the northwestern
U.S. early in the period.  Models depict this feature partially
phasing with a more substantial trough moving across western Canada
within the faster belt of westerlies to the north Day 4/Tuesday, and
then emerging into the north-central U.S. Day 5.  Afterward,
evolution of this trough begins to differ substantially amongst the
models.  The GFS depicts this trough evolving into cut-off low over
the Upper Mississippi Valley/Upper Great Lakes region Day
6/Thursday, which then lingers in place through Day 8 and beyond. 
Meanwhile, the ECMWF remains slowly progressive with the trough into
eastern North America through the period.  Given these substantial
differences, convective/severe potential cannot be reasonably
assessed beyond Day 5.

In the Day 4-5 time frame, a cold-frontal advance out of the western
U.S. into the northern Plains -- and eventually the Great Lakes
region -- is expected, in tandem with the progression of the
aforementioned upper trough.  However, with a surface high still
firmly in place from the eastern U.S. westward into the
central/southern Plains, Gulf moisture will remain suppressed, and
thus the likelihood for only meager destabilization across the
pre-frontal warm sector.  Therefore, severe risk is expected to
remain limited, thus not requiring a 15% areal outline associated
with this system through Day 5.

Day 2 Convective Outlook  
NWS Storm Prediction Center Norman OK
1258 AM CDT Sat Aug 31 2024

Valid 011200Z - 021200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE NORTHEAST AND MID-ATLANTIC REGIONS...AND SOUTHWESTWARD TO THE
SOUTHERN APPALACHIANS...

...SUMMARY...
Strong/isolated severe storms capable of producing gusty/damaging
winds will be possible from the Mid-Atlantic region to the central
and southern Appalachians, and possibly parts of New England on
Sunday.

...Synopsis...
An upper trough advancing initially across Ontario and the Upper
Great Lakes region will progress steadily eastward eastern Canada
and the northeastern U.S. through the period.  Upstream, ridging
will prevail over the West, though an eastern Pacific upper low will
approach the Oregon/northern California Coasts late in the period.

At the surface, an initial/weakening cold front lingering across New
England and the Atlantic Coast states during the first half of the
period will be gradually overtaken by a second/stronger front
shifting across the Great Lakes/Midwest early in the period.  By
Monday morning, the front will likely have reached/moved off the New
England and Mid-Atlantic Coasts, trailing southwestward across the
southeast and Gulf Coast regions.

...Parts of New England to the Mid-Atlantic region, and into the
central/southern Appalachians...
The remnant surface cold front -- gradually being overtaken by the
stronger/reinforcing front -- will serve as a focus for convective
activity Sunday.  As the upper trough steadily advances,
increasingly strong flow aloft will overspread the Northeast/New
England.  With that said however, substantial questions persist
across the Northeast -- particularly into New England -- given
likelihood for ongoing convection/cloud cover in the vicinity of the
initial/weakening front.  Thus, despite increasingly favorable
deep-layer shear that would otherwise support well-organized
convection, afternoon destabilization potential may be sufficiently
hampered so as to substantially limit severe potential.

Farther to the south -- across portions of the Mid-Atlantic region
and west-southwestward across the Appalachians, somewhat greater
destabilization potential is expected, but with weaker flow aloft as
compared to areas farther north.  Still, shear may prove sufficient
when combined with the anticipated/modest afternoon destabilization
to support stronger storms locally, and associated risk for gusty
outflow winds and local/minor wind damage during the afternoon and
early evening hours.

..Goss.. 08/31/2024

Day 3 Convective Outlook  
NWS Storm Prediction Center Norman OK
0215 AM CDT Sat Aug 31 2024

Valid 021200Z - 031200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe-weather potential is forecast to remain quite limited, and
isolated at best, across the U.S. on Monday.

...Discussion...
As a long-wave upper trough continues to shift across eastern Canada
and the eastern U.S. Monday, a cold front -- already off the New
England and Mid-Atlantic Coasts early in the day -- is forecast to
linger from the southeastern U.S. Atlantic Coast westward across the
Gulf Coast region.  This front will represent the southern/eastern
bounds of a cool/dry continental airmass from Canada -- represented
by large area of surface high pressure to encompass much of the
central and eastern CONUS.  Showers and thunderstorms are forecast
across the Southeast, Gulf Coast States, and Southern Plains area,
but with stronger flow aloft well to the north, severe-weather
potential should remain minimal.

In the West, an upper trough will shift east-northeastward across
the northwestern states, impinging on a persistent upper ridge. 
Showers and scattered to isolated thunderstorms are expected across
portions of the West ahead of this system, but with little in the
way of severe potential evident due to meager instability forecast
across the area.

..Goss.. 08/31/2024

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0101 AM CDT Sat Aug 31 2024

Valid 311200Z - 011200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CENTRAL APPALACHIANS AND UPPER OHIO VALLEY...

...SUMMARY...
Severe thunderstorms, associated with severe wind gusts and hail,
will be possible today from parts of the central Appalachians into
the Ohio and Tennessee Valleys. Isolated severe wind gusts will be
possible in parts of the northern Great Lakes.

...Central Appalachians/Ohio and Tennessee Valleys...
An upper-level trough will move through the Great Lakes region, with
the southern end of the trough located in the mid Mississippi
Valley. An associated cold front will advance southeastward through
the mid Mississippi Valley and southern Great Lakes. Ahead of the
front, a moist airmass will be in place with surface dewpoints in
the upper 60s and lower 70s F. Moderate instability is expected to
develop by midday ahead of much of the front. Further to the east, a
pre-frontal trough will be located from western New York and western
Pennsylvania southwestward into eastern Kentucky. Scattered
thunderstorms will form from near the front eastward to near the
pre-frontal trough. By early to mid afternoon, RAP forecast
soundings have MLCAPE peaking in the 1500 to 2000 J/kg range from
western New York southwestward into West Virginia. Along this
portion of the instability corridor, 0-6 km shear is forecast to be
in the 20 to 30 knot range. This, along with 0-3 km lapse rates near
7.5 C/km will support severe wind gusts with the more organized
bowing line segments. Hail will also be possible.

Further to the southwest into parts of the lower Ohio and Tennessee
Valleys, the models suggest that deep-layer shear will generally be
below 20 knots. Although steep low-level lapse rates could be enough
for a marginal wind-damage threat, the weakness in shear should keep
any threat isolated.

...Northern Great Lakes...
A cyclonic mid-level flow pattern will be in place today across much
of southern Canada and over the Great Lakes. Within this flow, a
shortwave trough and an associated cold front is forecast to move
southeastward toward the northern Great Lakes. Ahead of the front,
surface dewpoints in the 50s F will contribute to weak
destabilization by afternoon. Thunderstorms are expected to form
along and ahead of the front as instability peaks during the mid to
late afternoon. In spite of the weak instability, large-scale ascent
and strong deep-layer shear, associated with the shortwave trough,
could be enough for isolated severe wind gusts.

..Broyles/Moore.. 08/31/2024

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0750 PM CDT Fri Aug 30 2024

Valid 310100Z - 311200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE SOUTHERN GREAT LAKES SOUTHWESTWARD INTO THE MID MISSISSIPPI
VALLEY...

...SUMMARY...
Isolated severe storms, with marginally severe wind gusts and hail
will be possible this evening from southeast Lower Michigan
southwestward into the mid Mississippi Valley.

...Southern Great Lakes/Mid Mississippi Valley...
The latest mosaic water vapor imagery shows an upper-level trough
over the western Great Lakes extending southward into the mid
Mississippi Valley. An associated cold front is analyzed from
southeast Lower Michigan southwestward to near St. Louis, Missouri.
Scattered thunderstorms are ongoing along and near the front.
Surface dewpoints near and ahead of the front are in the upper 60s
and lower 70s F, and the RAP has MLCAPE in the 1200 to 2500 J/k/g
range. In addition, regional WSR-88D VWPs near the front have 0-6 km
shear ranging from near 20 knot at St. Louis to around 30 knots at
Detroit. This environment, combined with steep low-level lapse rates
near 7 C/km, should be enough for a marginally severe wind gusts for
a couple more hours this evening. Hail could also occur within the
cores of the stronger multicells.

..Broyles.. 08/31/2024