SPC Nov 12, 2026 1300 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 1300Z Day 1 Outlook


Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0648 AM CST Thu Nov 12 2026

Valid 121300Z - 131200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE COASTAL MID-ATLANTIC...

...SUMMARY...
Strong to severe thunderstorms capable of producing isolated severe
hail, damaging winds, and perhaps a tornado may impact parts of the
coastal Mid-Atlantic this afternoon.

...Coastal Mid-Atlantic...
Within large-scale upper troughing encompassing much of the
central/eastern CONUS, an embedded mid-level shortwave trough over
the OH Valley will move eastward across the Mid-Atlantic today. A
related weak surface low is also expected to develop eastward across
MD/DE/southern NJ this afternoon. While low-level moisture ahead of
these features should remain modest over land (generally low to mid
50s surface dewpoints), an effective warm front is forecast to
extend from the surface low across eastern PA into NJ. Thunderstorms
may initiate along/near this boundary by 16-18Z, with weak
instability expected to develop as filtered daytime heating occurs.
Stronger flow associated with a mid-level jet will tend to remain
displaced to the south of the coastal Mid-Atlantic through the day,
but veering winds with height through mid-levels will still support
around 25-40 kt of deep-layer shear.

Given cold mid-level temperatures (around -20 to -22 C at 500 mb)
and modestly steepened lapse rates aloft, any of the stronger cells
that develop could produce severe hail. Isolated damaging winds also
appear possible as this convection spreads from eastern PA into NJ
and vicinity before moving offshore. Low-level winds and related
shear should remain fairly modest, but a somewhat more favorable
zone for a tornado may exist if a persistent supercell can interact
with/cross the surface warm front this afternoon across eastern PA
into NJ. The northern extent of the severe risk will likely remain
constrained by the warm front, and it still appears likely that
appreciable severe risk will tend to remain offshore/south of Long
Island and southern New England.

..Gleason/Wendt.. 11/12/2026


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SPC Nov 12, 2026 0600 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 1200Z Day 1 Outlook


Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1121 PM CST Wed Nov 11 2026

Valid 121200Z - 131200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS TODAY ACROSS
PARTS OF SOUTHEASTERN PENNSYLVANIA...MUCH OF DELAWARE...ADJACENT
EASTERN MARYLAND AND SOUTHERN THROUGH CENTRAL NEW JERSEY...

...SUMMARY...
A couple of strong thunderstorms, accompanied by at least some risk
for severe weather, may impact parts of the northern Mid Atlantic
this afternoon.

...Discussion...
Downstream of amplified mid-level ridging, which may have reached
peak amplitude across the U.S. Intermountain West and Rockies
through much of the Canadian Prairies, a number of digging short
wave perturbations are forecast to contribute to the evolution of a
more prominent, positively tilted mid-level trough. This may
encompass most areas near and east of the Mississippi River through
the Atlantic Seaboard by 12Z Friday.

One leading short wave trough is generally forecast to turn east and
northeast of the Allegheny/Cumberland Plateau through the northern
Mid Atlantic by late this afternoon, before undergoing considerable
deformation as it progresses farther to the northeast. It appears
that this may be accompanied by an initially modest surface cyclone,
which may undergo notable deepening during the day while
redeveloping to the east-northeast of the Blue Ridge, before
occluding across the northern Mid Atlantic this evening.

...Northern Mid Atlantic...
Low-level moisture return inland of the coast appears likely to be
rather limited. However, boundary-layer dew points increasing
through the lower/mid 50s F, within a corridor along a warm frontal
zone to the east of the surface low, may be sufficient to yield
mixed-layer CAPE in excess of 500 J/kg when coupled with mid-level
cooling (including 500 mb temperatures of -20 to -22 C). Based on
forecast soundings, this may include buoyancy rooted near and just
off the surface, as low-level lapse rates steepen beneath the cold
air and boundary-layer humidity remains relatively high along the
frontal zone. Although low-level hodographs might not become more
than modestly large, in the presence of moderate deep-layer shear,
it appears at least possible that the environment could become
conducive to the evolution of one or two supercell structures posing
some risk for a tornado. Otherwise, stronger cells this afternoon
may be accompanied by small to perhaps marginally severe hail and
locally strong surface gusts, before weakening by evening.

..Kerr/Chalmers.. 11/12/2026


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SPC Nov 12, 2026 0100 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 0100Z Day 1 Outlook


Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0640 PM CST Wed Nov 11 2026

Valid 120100Z - 121200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THROUGH MID
EVENING ACROSS PARTS OF WESTERN INTO CENTRAL KENTUCKY...

...SUMMARY...
Strong thunderstorms posing a risk for small to marginally severe
hail, and perhaps locally gusty winds, may be maintained across
parts of west central into southeastern Kentucky and adjacent
northern Tennessee into at least late evening.

...01z Update...
Low-level moisture return to the warm sector of a modest (but
forecast to continue deepening) surface cyclone migrating through
the lower Ohio Valley has remained rather limited, at least where
forcing for ascent in the exit region of a 70-80+ kt cyclonic
mid-level jet has been sufficient to contribute to thunderstorm
development. With diurnal surface cooling now underway, it remains
unclear the extent to which mid-level cooling will maintain
sufficient destabilization to support a continuing risk for
marginally severe hail. However, despite a rapid transition to a
prominent westerly component to the flow from the surface through
around 850 mb, the latest Rapid Refresh suggests deeper
boundary-layer moistening is still possible into late evening along
the southern fringe of the stronger mid-level forcing overspreading
the south central into southeastern Kentucky/adjacent Tennessee
vicinity. If this occurs, thermodynamic profiles supportive of a
continuing risk for severe hail and locally gusty winds might be
maintained.

..Kerr.. 11/12/2026


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SPC Nov 11, 2026 1630 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 1630Z Day 1 Outlook


Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1030 AM CST Wed Nov 11 2026

Valid 111630Z - 121200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE LOWER OHIO AND WESTERN TENNESSEE VALLEYS...AS WELL AS ACROSS THE
EAST-CENTRAL FLORIDA PENINSULA...

...SUMMARY...
Thunderstorms capable of producing isolated hail, damaging winds,
and perhaps a tornado may occur this afternoon and evening across
parts of eastern Illinois into Indiana, western/central Kentucky,
and middle Tennessee. Isolated severe thunderstorms are also
possible across the east-central Florida Peninsula.

...Midwest/Lower Ohio Valley into Middle Tennessee...
Recent satellite imagery shows a lead shortwave trough moving into
northern IL, with another shortwave trough farther back northwest
moving into the Mid MO Valley. Showers and thunderstorms are ongoing
near the lead shortwave. Thunderstorm intensity has decreased over
the last half hour or so as these storms move into an environment
with less elevated buoyancy (as observed by the 12Z ILX sounding).
The lead shortwave is forecast to continue eastward into the OH
Valley while the second shortwave continues more southeastward into
the Lower OH Valley vicinity. The surface low currently over the
IA/IL border vicinity is forecast to progress eastward with the lead
wave while an attendant cold front sweeps southeastward through the
mid MS Valley/Mid-South, and lower OH Valley this afternoon and
evening.

Increasing low-level moisture is anticipated ahead of this front,
advecting northeastward into the region from the Ozarks/Mid-South
region. Recent surface analysis shows the mid 50s dewpoints are
still in northern AR, so there is some question as to how far
northeastward the greater low-level moisture will reach before
frontal passage. Current expectation is for the best overlap between
low-level moisture (and associated buoyancy) with the stronger
large-scale ascent will occur across southern IN and adjacent
western KY. Here, the combination of weak buoyancy (i.e. MLCAPE
around 500-800 J/kg) and 30-40 kt of deep-layer shear
oriented largely orthogonal to the surface cold front should support
a mix of bowing clusters and supercells. Isolated hail and damaging
gusts will be the primary risks. Hail is more likely with any more
cellular activity and damaging gusts more likely with any
fast-moving bowing segments. Modestly enhanced low-level
shear may also support a low-probability tornado risk, but a
tendency for low-level flow to veer to westerly should reduce
effective SRH with time through the late afternoon/evening. The
isolated severe risk should diminish with eastward extent this
evening across the lower OH Valley as front outruns the low-level
moisture and daytime heating wanes.

...Central/Southern Florida Peninsula...
Isolated to scattered thunderstorms are expected across the
central/southern FL Peninsula this afternoon. Glancing large-scale
ascent associated with a weak mid-level perturbation over the
Southeast should aid this convective development. A warm layer
around 700 mb could limit overall buoyancy, but 500 mb temperatures
will be around -9 to -11 deg C and most forecast sounding still show
1500+ J/kg of uninhibited MLCAPE this afternoon. Moderate deep-layer
shear will exists across the region as well. These conditions appear
supportive of marginally severe hail and gusty winds within the
stronger cores, which appear most probable along the east-central FL
Coast.

..Mosier/Halbert-K.. 11/11/2026


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