RSS Mesoscale Discussions from Storm Prediction Center
SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1049 AM CDT Thu Mar 19 2026
Valid 191630Z - 201200Z
...NO THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Thunderstorms are not forecast across the U.S. today or tonight.
...Synopsis...
Surface high pressure over the Southeast and a dry airmass over the
Gulf Basin will result in a persistent stable environment east of
the Rockies, precluding thunderstorm activity. A drier airmass is
also expected across south FL compared to previous days. Offshore
thunderstorms may approach the east-central FL coast tonight.
However, meager instability and nebulous forcing will likely limit
any thunderstorm coverage on land to less than 10 percent.
..Leitman.. 03/19/2026
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SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0300 PM CDT Thu Mar 19 2026
Valid 192000Z - 201200Z
...NO THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Thunderstorms are not forecast across the U.S. today or tonight.
...20Z Update...
The previous forecast (see below) remains unchanged.
..Squitieri.. 03/19/2026
.PREV DISCUSSION... /ISSUED 1049 AM CDT Thu Mar 19 2026/
...Synopsis...
Surface high pressure over the Southeast and a dry airmass over the
Gulf Basin will result in a persistent stable environment east of
the Rockies, precluding thunderstorm activity. A drier airmass is
also expected across south FL compared to previous days. Offshore
thunderstorms may approach the east-central FL coast tonight.
However, meager instability and nebulous forcing will likely limit
any thunderstorm coverage on land to less than 10 percent.
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SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1230 PM CDT Thu Mar 19 2026
Valid 201200Z - 211200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS CENTERED ON THE
UPPER OHIO VALLEY...
...SUMMARY...
Strong to locally severe thunderstorms are possible across parts of
the Upper Ohio Valley, mainly late Friday afternoon into Friday
evening.
...Synopsis...
An upper ridge will remain in place over the Southwest on Friday,
while a large-scale upper trough will cover much of the eastern
CONUS. Within the large-scale trough, an embedded shortwave will
move from the Upper Great Lakes towards the northern Mid Atlantic
and New England. A surface low will move from parts of lower MI
toward New England through the period, as trailing cold front moves
across the Ohio Valley and Mid Atlantic.
...Parts of the mid/upper Ohio Valley...
Modest low-level moisture will return through the day along/ahead of
the approaching cold front across parts of the Ohio Valley/Allegheny
Plateau region. Regarding prefrontal dewpoints, guidance generally
ranges from the low 50s F (HRRR/WRF-ARW) to mid/upper 50s F (NAM and
other HREF members). In the presence of strong deep-layer
flow/shear, the magnitude of moisture return will determine the
level and areal extent of any organized severe potential.
If moisture return becomes sufficient to support MLCAPE of around
500 J/kg or greater, then a few stronger updrafts and perhaps
marginal supercell structures could develop by late afternoon or
early evening, as convective temperatures are approached or breached
and glancing large-scale ascent impinges upon the region. Despite
the generally weak instability, any robust storms could pose a
threat of marginally severe hail and perhaps locally gusty/damaging
winds, given the presence of favorable shear and rather cold
temperatures aloft. A brief tornado also cannot be ruled out, though
this will be more conditional on richer low-level moisture return
and maintenance of surface-based convection.
With generally low-quality moisture noted in Thursday morning
observations, sufficient moisture return for an organized severe
threat on Friday remains quite uncertain. However, given the
presence of very favorable wind profiles and at least some signal
for near-surface-based storm development during the late afternoon
and evening, a conditional Marginal Risk has been added for Friday
across parts of the Upper Ohio Valley. A conditionally favorable
environment will extend outside of the Marginal Risk into parts of
the mid/lower Ohio Valley, but the signal for storm development
currently decreases substantially with southwestward extent.
..Dean.. 03/19/2026
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SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0229 PM CDT Thu Mar 19 2026
Valid 211200Z - 221200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Isolated general thunderstorms are possible Saturday over the
Tennessee Valley to southern Appalachians, and also across parts of
the Upper Midwest.
...Synopsis...
Some deamplification of the upper-level pattern is expected on
Saturday, with a transition to more zonal flow across much of the
western and central CONUS. A large-scale upper trough will remain in
place across much of the East, with a weak embedded shortwave
expected to move from the Mid MS Valley toward the Southeast.
...TN Valley into parts of GA and the Carolinas...
A weak front that moves into the region late D2/Friday is forecast
to stall and potentially become rather ill-defined with time, as a
surface low deepens well to the northwest across the north-central
Plains. A remnant moisture/instability gradient is still depicted by
guidance to be draped from TN into the southern Appalachians and SC
by Saturday afternoon. Modest destabilization (with MLCAPE
potentially approaching 1000 J/kg) will be possible along/south of
the remnant boundary, and isolated storm development may occur as
the weakening shortwave trough moves across the region.
Deep-layer shear will generally remain rather modest within the weak
northwest-flow regime, and storm coverage may tend to remain limited
due to weak large-scale ascent. As a result, confidence in an
organized-severe threat is currently too low for probabilities,
though isolated strong storms with localized hail and/or wind-damage
potential cannot be ruled out, and a Marginal Risk may eventually be
needed for parts of the region.
..Dean.. 03/19/2026
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