RSS Mesoscale Discussions from Storm Prediction Center
SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1054 PM CST Sat Dec 27 2025
Valid 281200Z - 291200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM EASTERN
MISSOURI INTO WESTERN OHIO...
...SUMMARY...
Strong thunderstorms may develop over Missouri and Illinois today,
and move across parts of Indiana, Kentucky and Ohio through evening.
A few damaging wind gusts appear to be the primary severe threat.
...Synopsis...
An upper low will deepen as it moves from the northern Plains into
the upper Great Lakes, with rapidly intensifying mid and high level
flow and strong height falls spreading across much of the Midwest.
At the surface, low pressure will deepen from northern MO this
morning into Lower MI by 00Z, with an intense cold front trailing
southwest from the low. By mid afternoon, this front will extend
from northern IL into eastern MO and northwest AR, with southerly
winds aiding northward moisture transport with dewpoints near 60 F.
A warm front will lift across IL, IN, and southern Lower MI as the
low develops northeastward. Lift along these boundaries will support
scattered thunderstorms, with the greatest probabilities generally
near the surface low track from northeast MO into Lower MI. Given
strong wind fields, sporadic severe storms may occur.
...From MO into OH...
For the morning hours, scattered elevated thunderstorms appear
likely from eastern IA across northern IL, IN, and southern Lower MI
north of the warm front and in the zone of theta-e advection.
Forecast soundings indicate sufficient MUCAPE for perhaps small
hail.
From midday into the afternoon, SBCAPE over 500 J/kg is forecast
ahead of the cold front and near the surface low from eastern MO
across central IL and into IN. This is conditionally a favorable
area for supercells, though in this case the lack of surface heating
along with a cap below 700 mb suggest the bulk of the diurnal
convection should be relegated to the cold front, in which case a
linear mode seems likely. Still, given hodographs favoring
supercells, a few embedded areas of rotation will be possible and a
brief tornado cannot be ruled out. Otherwise, damaging winds will be
the primary concern
..Jewell/Squitieri.. 12/28/2025
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SPC 0700Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1143 PM CST Sat Dec 27 2025
Valid 291200Z - 301200Z
...NO THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Thunderstorms are not expected on Monday or Monday Night.
...Discussion...
A deep surface cyclone near Lake Huron at 12Z Monday will occlude as
it tracks into QC. A full-latitude occluded/cold front will arc
across NY to the FL Panhandle and western Gulf on Monday morning,
before clearing the entire Atlantic Seaboard by Monday night.
Scant elevated buoyancy may be present in two regimes on Monday
morning. One within the low-level warm conveyor ahead of the
occluded portion of the front across parts of eastern NY into New
England. The second immediately behind the cold front along the Rio
Grande in Deep South TX. Thunderstorm probabilities, while nonzero,
still appear to be below 10 percent in both areas. In between, weak
mid-level lapse rates should support only shallow convection across
the Southeast as the front moves east.
..Grams.. 12/28/2025
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SPC 0830Z Day 3 Outlook
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
1242 AM CST Sun Dec 28 2025
Valid 301200Z - 311200Z
...NO THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Thunderstorms will not occur on Tuesday or Tuesday night.
...Discussion...
Conditions will be too dry/stable for lightning-producing convection
across the CONUS through the period.
..Grams.. 12/28/2025
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Day 4-8 Outlook
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0238 AM CST Sun Dec 28 2025
Valid 311200Z - 051200Z
...DISCUSSION...
Return flow will ensue along the western Gulf Coast mid-week,
yielding air mass modification from the prior continental intrusion.
Bulk of deterministic guidance has trended toward earlier EC-AIFS
signals of a low-amplitude shortwave trough progressing east across
the southern states through late week. While run-to-run
predictability and spread across models remains subpar, convective
potential should increase by D6-7/Friday-Saturday across parts of
the Gulf Coast States. At this point, with only modest cyclogenesis
consistently progged, overall severe potential still appears
marginal. Latest ML guidance from SPC-CSU and NSSL for the GEFS, and
yesterday's NCAR for the ECENS, support this notion with individual
day probabilities holding at 5 percent or less.
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