RSS Mesoscale Discussions from Storm Prediction Center
SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1130 PM CST Thu Nov 13 2025
Valid 141200Z - 151200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Thunderstorm activity is forecast to be minimal across the majority
of the U.S. today. Isolated weak activity may affect parts of
southern California into Saturday morning.
...Synopsis and Discussion...
A positive-tilt upper trough will be just off the West Coast Friday
morning, with an offshore upper low translating southward through
the period. A stronger disturbance is forecast to rotate around the
base of this trough into Saturday morning, with midlevel winds
increasing and becoming nearly southerly as cooling aloft
approaches.
At the surface, low pressure will deepen late in the period off the
coast of southern CA and toward the Channel Islands. Precipitation
will increase in coverage at that time, with a few lightning flashes
possible mainly offshore. Low-level wind fields and shear will be
modest, and SBCAPE should remain near zero through 12Z Saturday over
land. As such, overall thunderstorm activity should be minimal over
land.
Elsewhere, an upper ridge will temporarily exist from the southern
Plains into the Great Lakes before the base of a broadening upper
trough moves into the northern Plains and upper Midwest. High
pressure over the southeast combined with strongly veering low-level
winds should keep conditions stable over those areas through 12Z
Saturday.
..Jewell/Moore.. 11/14/2025
Read more
SPC 0700Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1132 PM CST Thu Nov 13 2025
Valid 151200Z - 161200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE UPPER
OHIO VALLEY...
...SUMMARY...
Showers and a few thunderstorms may be accompanied by strong wind
gusts across parts of the upper Ohio Valley Saturday evening.
...Upper Ohio Valley...
An upper ridge over from Ontario/Quebec into the Ohio Valley will
break down/shift east across the Northeast through Saturday evening
as a deepening shortwave trough moves across the Great Lakes and
Midwest. At this occurs, a deepening surface low will pivot eastward
across southern Ontario and into New England by early Sunday
morning. A trailing cold front will develop southward across the
Lower Great Lakes/Ohio Valley and Northeast during the nighttime
hours. Ahead of this feature, southerly low-level flow will
transport modest boundary-layer moisture northward, with surface
dewpoints expected to mainly be in the 50s F.
Forecast soundings indicated meager instability may develop (less
than 500 J/kg) with cooler temperatures aloft in the 700-500 mb
layer. The lower troposphere thermodynamic profiles are somewhat
lackluster, with warmer 850-700 mb temperatures noted in both RAP
and NAM soundings, resulting in poor lapse rates. Nevertheless,
strengthening westerly flow in the lowest 3 km to around 40-50 kt
amid meager instability could result in isolated strong gusts for a
few hours during the evening before convection weakens with eastward
extent into the overnight hours.
...Coastal Southern CA...
An upper low offshore the southern CA coast will move inland on
Saturday. At the surface, a weak low and associated wind shift will
move inland in the 12-18z time period. Forecast soundings indicate
very meager surface-based instability will be present. Currently,
forecast guidance varies considerably, with RAP forecast soundings
showing virtually no surface-based instability compared to NAM
forecast soundings showing 100-300 J/kg SBCAPE, with HRRR forecast
soundings somewhere in between. Nevertheless, 30-40 kt flow in the
1-3 km layer could result in locally gusty winds, especially in
higher elevations through midday, with low-topped convective
elements.
..Leitman.. 11/14/2025
Read more
