RSS Mesoscale Discussions from Storm Prediction Center
SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1130 AM CDT Sun Mar 15 2026
Valid 151630Z - 161200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
AND TONIGHT ACROSS MUCH OF THE LOWER/MID MISSISSIPPI VALLEY...LOWER
OHIO VALLEY...TENNESSEE VALLEY...AND SOUTHEAST...
...SUMMARY...
Numerous to widespread severe/damaging winds and embedded tornadoes
will accompany an intense squall line across much of the lower/mid
Mississippi Valley this afternoon and evening. A couple of strong
tornadoes are also possible within and just ahead of this line
across parts of the lower Ohio Valley into the Mid-South and Gulf
Coast regions. The severe wind and tornado threat will likely
persist through tonight across portions of the Ohio
Valley/Southeast.
...Lower Mississippi Valley/Southeast into the Ohio
Valley/Midwest...
Pronounced upper troughing over the northern/central Plains late
this morning will further amplify through the period as it ejects
east-northeastward across much of the MS Valley/Midwest. A 992 mb
surface low over northern MO will likewise develop northeastward
across the Midwest through the day, reaching northeast IL/northwest
IN by this evening and northern Lower MI by the end of the period.
Primary low-level jet will focus northward across the OH
Valley/Midwest this afternoon and evening, with a trailing/southern
portion present across parts of the Mid-South and lower MS Valley.
Associated strong low-level warm/moist advection will continue to
occur ahead of a sharp surface cold front that is expected to sweep
quickly east-southeastward through tonight over much of the
lower/mid MS Valley, OH/TN Valleys, and Southeast.
Low-level moisture remains fairly shallow/limited ahead of the cold
front per latest surface observations and area 12Z observed
soundings (ILX, SGF, JAN, LIX). Still, generally 50s surface
dewpoints should be present in a narrow warm sector across the OH
Valley/Midwest by late afternoon/early evening, with somewhat
greater moisture (upper 50s to low 60s surface dewpoints) southward
into the lower/mid MS Valley. Large-scale ascent attendant to the
approaching upper trough will aid in the erosion of a substantial
cap noted along/ahead of the cold front by early afternoon (18-20Z).
With even modest/filtered daytime heating, at least weak instability
should develop in a narrow corridor ahead of the front. This gradual
destabilization will support the potential for rapid thunderstorm
development within the next few hours.
General consensus of latest guidance is that a QLCS will quickly
strengthen/consolidate through the mid to late afternoon into the
evening as it moves quickly eastward across AR/MO and the lower/mid
MS Valley and lower OH Valley. Deep-layer shear of 40-50+ kt
associated with a strengthening west-southwesterly mid-level jet
overspreading the warm sector will support organization with the
maturing QLCS. Given the expected strength of the flow in the
boundary layer (50-60+ kt), numerous to potentially widespread
severe/damaging winds up to 60-80 mph are expected wherever the QLCS
can remain surface based. Strong low-level shear will also be
present to foster embedded mesocirculations and the potential for
several QLCS tornadoes.
The opportunity for supercells to develop ahead of the squall line
remains uncertain, as residual low-level capping may inhibit open
warm sector development. Still, greater instability should be
present from the western KY/TN vicinity southward into the lower MS
Valley. Any supercells that can form ahead of the line across these
areas and/or remain at least semi-discrete within the line could
produce strong (EF-2+) tornadoes, as low-level shear and related
elongated/curved hodographs will be quite favorable for updraft
rotation. Although boundary-layer instability will become
increasingly weak with northward extent into the OH Valley tonight,
a continued threat for numerous severe/damaging winds will likely
continue with the QLCS as it shifts eastward across the OH/TN
Valleys and much of the Southeast this evening through early Monday
morning. Have therefore expanded/combined the wind-driven Enhanced
Risk areas in southern/central MS/AL into western GA and eastern TN.
Some chance for pre-frontal supercells and strong tornado potential
ahead of the QLCS may also exist late tonight across portions of
southeast AL, the FL Panhandle, and southwest GA.
...Florida Peninsula into the Carolinas...
Low-level moisture will gradually spread northward through tonight
from the FL Peninsula to the southern Appalachians and into parts of
the Carolinas, well ahead of the amplifying upper trough over the MS
Valley. While forcing will remain generally weak/nebulous, there is
some chance for isolated hail/damaging winds with thunderstorms this
afternoon across much of the FL Peninsula and the Keys. The severe
threat across coastal GA/SC/NC appears conditional on thunderstorms
spreading inland from the Gulf Stream tonight into early Monday
morning. However, an isolated threat for damaging winds and perhaps
a tornado would exist in a gradually improving environment if these
cells form and move inland. Have therefore maintained the Marginal
Risk across this region with no changes.
..Gleason/Lyons.. 03/15/2026
Read more
SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0257 PM CDT Sun Mar 15 2026
Valid 152000Z - 161200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
INTO TONIGHT ACROSS MUCH OF THE LOWER/MID-MISSISSIPPI VALLEY...LOWER
OHIO VALLEY...TENNESSEE VALLEY...AND SOUTHEAST...
...SUMMARY...
Numerous to widespread severe/damaging winds and embedded tornadoes
will accompany an intense squall line across much of the lower/mid
Mississippi Valley this afternoon and evening. A couple of strong
tornadoes are also possible within and just ahead of this line
across parts of the lower Ohio Valley into the Mid-South and Gulf
Coast regions. The severe wind and tornado threat will likely
persist through tonight across portions of the Ohio
Valley/Southeast.
...20Z Update...
Some trimming to severe/thunder probabilities was done across
Missouri given the progression of the sharp cold front. Lapse rate
and shear profiles will favor supercells from near the Sabine Valley
into the Mississippi Delta region. There, hail to around 2 inches is
conditionally possible. The greatest potential for strong tornadoes
still appears to be within the mid-Mississippi Valley. Tornado
probabilities were adjusted based on the latest guidance. Lastly,
higher wind probabilities (45%) were expanded southeastward where
there is an increased signal in guidance for a coherent line of
convection to maintain intensity this evening/overnight. See the
previous discussion for additional details.
..Wendt.. 03/15/2026
.PREV DISCUSSION... /ISSUED 1130 AM CDT Sun Mar 15 2026/
...Lower Mississippi Valley/Southeast into the Ohio
Valley/Midwest...
Pronounced upper troughing over the northern/central Plains late
this morning will further amplify through the period as it ejects
east-northeastward across much of the MS Valley/Midwest. A 992 mb
surface low over northern MO will likewise develop northeastward
across the Midwest through the day, reaching northeast IL/northwest
IN by this evening and northern Lower MI by the end of the period.
Primary low-level jet will focus northward across the OH
Valley/Midwest this afternoon and evening, with a trailing/southern
portion present across parts of the Mid-South and lower MS Valley.
Associated strong low-level warm/moist advection will continue to
occur ahead of a sharp surface cold front that is expected to sweep
quickly east-southeastward through tonight over much of the
lower/mid MS Valley, OH/TN Valleys, and Southeast.
Low-level moisture remains fairly shallow/limited ahead of the cold
front per latest surface observations and area 12Z observed
soundings (ILX, SGF, JAN, LIX). Still, generally 50s surface
dewpoints should be present in a narrow warm sector across the OH
Valley/Midwest by late afternoon/early evening, with somewhat
greater moisture (upper 50s to low 60s surface dewpoints) southward
into the lower/mid MS Valley. Large-scale ascent attendant to the
approaching upper trough will aid in the erosion of a substantial
cap noted along/ahead of the cold front by early afternoon (18-20Z).
With even modest/filtered daytime heating, at least weak instability
should develop in a narrow corridor ahead of the front. This gradual
destabilization will support the potential for rapid thunderstorm
development within the next few hours.
General consensus of latest guidance is that a QLCS will quickly
strengthen/consolidate through the mid to late afternoon into the
evening as it moves quickly eastward across AR/MO and the lower/mid
MS Valley and lower OH Valley. Deep-layer shear of 40-50+ kt
associated with a strengthening west-southwesterly mid-level jet
overspreading the warm sector will support organization with the
maturing QLCS. Given the expected strength of the flow in the
boundary layer (50-60+ kt), numerous to potentially widespread
severe/damaging winds up to 60-80 mph are expected wherever the QLCS
can remain surface based. Strong low-level shear will also be
present to foster embedded mesocirculations and the potential for
several QLCS tornadoes.
The opportunity for supercells to develop ahead of the squall line
remains uncertain, as residual low-level capping may inhibit open
warm sector development. Still, greater instability should be
present from the western KY/TN vicinity southward into the lower MS
Valley. Any supercells that can form ahead of the line across these
areas and/or remain at least semi-discrete within the line could
produce strong (EF-2+) tornadoes, as low-level shear and related
elongated/curved hodographs will be quite favorable for updraft
rotation. Although boundary-layer instability will become
increasingly weak with northward extent into the OH Valley tonight,
a continued threat for numerous severe/damaging winds will likely
continue with the QLCS as it shifts eastward across the OH/TN
Valleys and much of the Southeast this evening through early Monday
morning. Have therefore expanded/combined the wind-driven Enhanced
Risk areas in southern/central MS/AL into western GA and eastern TN.
Some chance for pre-frontal supercells and strong tornado potential
ahead of the QLCS may also exist late tonight across portions of
southeast AL, the FL Panhandle, and southwest GA.
...Florida Peninsula into the Carolinas...
Low-level moisture will gradually spread northward through tonight
from the FL Peninsula to the southern Appalachians and into parts of
the Carolinas, well ahead of the amplifying upper trough over the MS
Valley. While forcing will remain generally weak/nebulous, there is
some chance for isolated hail/damaging winds with thunderstorms this
afternoon across much of the FL Peninsula and the Keys. The severe
threat across coastal GA/SC/NC appears conditional on thunderstorms
spreading inland from the Gulf Stream tonight into early Monday
morning. However, an isolated threat for damaging winds and perhaps
a tornado would exist in a gradually improving environment if these
cells form and move inland. Have therefore maintained the Marginal
Risk across this region with no changes.
Read more
SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1230 PM CDT Sun Mar 15 2026
Valid 161200Z - 171200Z
...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS IN PARTS OF
SOUTH CAROLINA...NORTH CAROLINA...VIRGINIA...MARYLAND...AND
WASHINGTON D.C...
...SUMMARY...
Widespread severe storms are anticipated on Monday across the
Southeast and Mid-Atlantic States. Tornadoes, some strong, and
particularly damaging winds are most likely from parts of South
Carolina to Maryland during the afternoon.
...Synopsis...
An expansive upper trough from WI to the Ark-La-Tex will further
amplify as the basal portion pivots rapidly northeastward towards
the Appalachians. A deep surface cyclone over Lower MI will progress
into QC, with an occluded front arcing southward to a minor low over
western to central NY by Monday afternoon. A sharp cold front will
extend south of this low across the Southeast into the northeast
Gulf, sweeping east across the entire Atlantic Seaboard by 12Z
Tuesday.
...East...
No change has been made to the ongoing level 4-MDT risk, with some
expansion of the 3-ENH in GA, as well as expansions of 1-2/MRGL-SLGT
across NY and FL. The highly meridional deep-layer flow regime
suggests that surface-based instability appears more likely to
develop into NY on Monday afternoon. This type of flow regime, along
with substantial early-day convection south, both render some
uncertainty on intensity amplitudes for wind/tornado across much of
the ENH-MDT risk areas.
A broken band of pre-frontal convection should be ongoing at 12Z
Monday from the lee of the southern Appalachians to the FL
Panhandle. The downstream environment will already be favorable for
supercells including strong tornado potential. With mid to upper 60s
surface dew points and initially modestly steep mid-level lapse
rates, a plume of moderate buoyancy with MLCAPE of 1000-2000 J/kg
should diurnally expand from north FL through at least SC. Any
semi-discrete supercells in this environment will have the potential
to produce a strong tornado and large hail through early afternoon
before large-scale outflow likely shifts offshore of the GA/north FL
coast.
Destabilization farther north from NC to the DE Valley appears more
uncertain, with potential for near-coastal convection within the
low-level warm conveyor limiting more expansive/robust
boundary-layer heating. A plume of weak MLCAPE up to 1000 J/kg
should still develop across the Piedmont into parts of the coastal
plain. Although flow fields will be highly meridional, they will be
quite strong with an intense 700-mb jet strengthening across the
Southeast behind the surface cold front. This will yield enlarged
low-level hodograph curvature across much of the pre-frontal
warm-moist sector.
Even weak boundary-layer heating will be sufficient for
intensification of an extensive QLCS from western to central
portions of NY/PA southward through VA/NC towards midday/early
afternoon. Embedded supercell structures should be most pronounced
south, where breaks in the QLCS are more probable. Some of these
could be long-track with sporadic strong tornadoes, in addition to
the background widespread damaging winds anticipated with the QLCS.
This activity will eventually interact with cool trajectories near
the coastal Atlantic and should result in waning of severe potential
in the Northeast near sunset.
..Grams.. 03/15/2026
Read more
SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0154 PM CDT Sun Mar 15 2026
Valid 171200Z - 181200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Thunder potential appears negligible on Tuesday and Tuesday night.
...Discussion...
With a continental air mass enveloping the Gulf and Atlantic Coasts
by Tuesday morning, thunder potential will become negligible.
Isolated convection might linger near the extreme southern FL
Peninsula and Keys just beyond 12Z Tuesday as the front reaches the
Straits. Thunder probabilities over land appear to be around 10
percent through 15Z.
Elsewhere, conditions will be too dry/stable for lightning-producing
convection through the period.
..Grams.. 03/15/2026
Read more
