SPC May 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
1131 AM CDT Mon May 11 2026

Valid 111630Z - 121200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE COASTAL
CAROLINAS ITO THE EASTERN FLORIDA PENINSULA...AND ACROSS THE CENTRAL
GULF COAST...

...SUMMARY...
Isolated severe storms with locally damaging wind gusts and hail are
possible this afternoon from the coastal Carolinas into the Florida
Peninsula, and along the central Gulf Coast.

...Synopsis...
Upper pattern across the CONUS this morning consists of western
ridging and eastern troughing. A pair of shortwave troughs are
embedded within the parent trough, one moving through the middle OH
Valley and the other farther south across TX. A convectively
generated vorticity maximum moving across the western Gulf precedes
the TX shortwave. Farther west, a shortwave trough is moving through
the northern periphery of the upper ridging over northern MT and
adjacent southern Saskatchewan.

Recent surface analysis places a low over the eastern NC/SC border
vicinity, with a cold front extending southwestward through the
Southeast and southern AL through the far western Gulf into Deep
South TX. Another low exists farther northwest over southern
Saskatchewan, with a cold front extending south-southwestward from
this low across eastern into south-central MT.

...Eastern SC/Far Southern NC...
Regional radar imagery shows isolated thunderstorms currently
ongoing near the surface low over the eastern NC/SC border vicinity.
A modest increase in buoyancy is anticipated ahead of these storms
over the next few hours. This buoyancy coupled with strong shear
could result in a few bowing segments capable of damaging gusts.
Additional isolated thunderstorm development is anticipated late
this afternoon as the weak cold front moves eastward across SC.
Moderate buoyancy and shear will support the potential for a few
more robust/organized updrafts capable of isolated hail and/or
damaging gusts.

...Eastern FL...
Warm/moist conditions are expected today over the FL Peninsula, with
temperatures over the interior warming into the 90s. Deep westerly
flow will focus convergence along the east-coast sea-breeze, leading
to scattered afternoon thunderstorms. Sufficient deep-layer vertical
shear may result in isolated strong-severe storms producing
gusty/damaging winds and hail.

...Northern/eastern ND into eastern SD...
Despite limited low-level moisture, modest buoyancy may develop late
this afternoon/early this evening amid cooling mid-level
temperatures and increasing mid-level moisture. This buoyancy will
develop atop a deeply mixed boundary layer, supporting the potential
for strong gusts if any updrafts can deepen/mature. Given the weak
and elevated nature of the buoyancy, developing a mature updraft
capable of lightning will be difficult and the current expectation
is for most of this activity to be shallow and non-lightning
producing. That being said, gusty surface winds are possible with
any convection does develop atop the deeply mixed boundary layer.

...Coastal LA/MS/AL...
The convectively generated shortwave trough over the western Gulf
mentioned in the synopsis (and associated surface low) are expected
to progress eastward throughout the day, while the stronger
shortwave trough back across TX also progress east-southeastward.
Easterly/southeasterly low-level flow will be maintained north of
the Gulf low, increasing low-level convergence along the slow-moving
frontal zone. This convergence will be augmented by ascent attendant
to the TX shortwave, with numerous showers and thunderstorms likely.
Poor lapse rates will limit buoyancy, although moderate deep-layer
shear could support a few deeper, more organized updrafts. Primary
risk over this area is heavy rain (as noted in the WPC Day 1
Excessive Rainfall Outlook), but a few water-loaded downbursts
capable of wind damage are possible as well.

..Mosier/Chalmers.. 05/11/2026


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SPC May 11, 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
0713 AM CDT Mon May 11 2026

Valid 111300Z - 121200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE COASTAL
CAROLINAS INTO THE FLORIDA PENINSULA...AND ALONG THE CENTRAL GULF
COAST...

...SUMMARY...
Isolated severe storms with locally damaging wind gusts and hail are
possible Monday afternoon from the coastal Carolinas into the
Florida Peninsula, and along the central Gulf Coast.

...Carolinas...
A large upper trough is present today over the eastern states, with
a weak cold front sagging southward across the Carolinas. Ample
low-level moisture is present to the south of the front from central
SC into southeast NC, with dewpoints in the mid 60s. Pockets of
daytime heating will destabilize this region, with the potential for
isolated thunderstorm development by early afternoon. Low-level
winds are veered and relatively weak, limiting frontal convergence
and shear. A few strong storms may occur with locally gusty winds
and hail. But the overall threat appears marginal.

...Eastern FL...
Warm/moist conditions are expected today over the FL Peninsula with
temperatures over the interior warming into the 90s. Deep westerly
flow will focus convergence along the east-coast sea-breeze, leading
to scattered afternoon thunderstorms. Sufficient deep-layer
vertical shear may result in isolated strong-severe storms producing
gusty/damaging winds and hail.

...Coastal LA/MS/AL...
A convectively-aided shortwave trough over east TX will continue to
track eastward across the central Gulf Coast region today. The
combination of daytime heating and dewpoints in the mid-upper 60s
will yield moderate CAPE values, leading to relatively widespread
afternoon thunderstorms from southeast LA into southern MS/AL.
Low-level winds are weak and lapse rates are rather weak.
Nevertheless, cooler temperatures aloft and degree of instability
will support a risk of occasionally intense cells capable of
damaging winds and hail.

..Hart/Wendt.. 05/11/2026


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SPC May 11, 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
1242 AM CDT Mon May 11 2026

Valid 111200Z - 121200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE COASTAL
CAROLINAS INTO THE FLORIDA PENINSULA...AND ALONG THE CENTRAL GULF
COAST...

...SUMMARY...
Isolated severe storms with locally damaging wind gusts and hail are
possible Monday afternoon from the coastal Carolinas into the
Florida Peninsula, and along the central Gulf Coast.

...Synopsis...

Within the base of broader-scale troughing over eastern North
America, a lead short-wave trough will progress from the TN Valley
through the Carolinas on Monday, in tandem with a mid-level jet
streak. Farther to the southwest, a vorticity maximum over western
TX as of late evening is expected to progress east through the
Sabine River Valley to along the central Gulf Coast Monday afternoon
into Monday night. Elsewhere, a strong short-wave trough and
attending mid/upper-level wind maxima will crest the western U.S.
ridge axis along the International Border before turning more
southeast into the northern Plains and upper MS Valley Monday night
into Tuesday morning.

At the surface, a cold front will settle south through the lower MS
Valley and Southeast with low pressure developing along the boundary
over coastal SC or far southeast NC by early afternoon. Elsewhere,
an area of low pressure will track east-southeast through southern
parts of Saskatchewan and Manitoba with an associated cold front
sweeping southeast through the northern High Plains. A trough will
precede the cold front with that feature shifting east into the
central Dakotas by early evening.

...Coastal Carolinas into the eastern Florida Peninsula...

Latest model guidance is suggestive that surface-based thunderstorm
development may occur as early a mid to late morning along or ahead
of the cold front from the SC piedmont into the coastal plain as
forcing for ascent increases downstream from the approaching
short-wave trough. Subsequent storm development is also expected
farther northeast along the front into southeast NC by late morning
into early afternoon.

Even with the relatively early storm development, forecast soundings
indicate the presence of a moderately unstable warm sector with
MLCAPE approaching 1500 J/kg. Vertical shear will steadily increase
with the arrival mid-level jet streak, such that some transient
supercell structures may evolve, especially in the vicinity of the
weak surface low. The strongest storms will be capable of isolated
occurrences of damaging winds and marginally severe hail into mid
afternoon before moving offshore. Generally weak low-level shear
should limit tornado potential.

Additional strong to marginally severe storms appear possible along
the cold front, as well as the Atlantic Coast sea breeze from
southeast GA southward into the Fl Peninsula. The combination of a
moist and moderately unstable air mass (MLCAPE of 1500-2500 J/kg)
with 30-40 kt of effective bulk shear will be supportive of some
storm organization with an attendant risk for damaging, wet
microbursts and perhaps some marginally severe hail.

...Central Gulf Coast...

Increased forcing for ascent associated with the short-wave trough
moving into the Sabine River Valley is expected to contribute to an
increase thunderstorm development Monday afternoon across southern
parts of LA and MS, potentially into southwest AL. A moist and
moderately unstable air mass will coincide with 30-35 kt of
effective bulk shear, with the 00z convection-allowing models
suggesting some potential for cold pool organization along the
coast. The primary hazard is expected to be locally damaging outflow
winds.

...Northern Plains into Upper Mississippi Valley...

A plume of steep, mid-level lapse rates (7.5-8.5 C/km) will
overspread the northern Plains Monday, downstream from the
approaching short-wave trough. The boundary-layer ahead of the
pre-frontal trough will remain rather dry with dewpoints in the 30s
to perhaps low/mid 40s, which in turn will limit MLCAPE to 200-300
J/kg. Strong, diurnal heating in the vicinity of the surface trough
coupled with increasing height falls aloft may be sufficient to
support isolated, high-based thunderstorms by late afternoon into
early evening with the potential for locally strong wind gusts.
Thunderstorms may tend to increase in areal coverage later Monday
evening into Monday night across the upper MS Valley, aided by a
nocturnally strengthening low-level jet. By that time, the
convection is likely to be elevated and capable of small hail.

No wind/hail probabilities will be assigned to the area at this
time. However, model trends will be monitored for greater air mass
destabilization, which could warrant 5% probabilities and a level
1/Marginal Risk.

..Mead/Weinman.. 05/11/2026


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SPC May 11, 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
0730 PM CDT Sun May 10 2026

Valid 110100Z - 111200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS EVENING
INTO TONIGHT IN CENTRAL TEXAS...

...SUMMARY...
Scattered large hail (some 2+ inches) and numerous severe/damaging
wind gusts (isolated 75+ mph) are expected this evening across parts
of central Texas.

...Central Texas to the Texas Coast and deep South Texas...

As of 00:15z, volumetric radar data indicated an HP supercell
gradually evolving into a larger-scale bowing complex over
McCulloch, San Saba, and Mason counties with a separate supercell
complex over Coryell county, which recently produced hail up to four
inches in diameter. Surface observations and objective analysis
indicate the presence of a warm and moist inflow air mass with
estimated MLCAPE of 2000-3000 J/kg. While deep-layer shear isn't
particularly strong, the observed supercell structures indicate
sufficient shear exists to support organized storm modes given the
degree of instability.

Current thinking is that the separate thunderstorm regimes mentioned
above will eventually merge along a common cold pool, with a
broader-scale MCS accelerating south-southeast through the remainder
of central TX this evening. Corridors of damaging winds in excess of
75 mph appear likely within the core of the bowing complex. The very
large hail (> 2") threat is expected to persist for the next hour or
two with the dominant supercell structures. Hail sizes should
diminish with time as convection transitions to more of an outflow
dominant system.

The wind damage threat is expected to become more isolated late
tonight as the convective system approaches the TX Coast and deep
South Texas owing to gradual cooling and stabilization of the
boundary layer.

..Mead.. 05/11/2026


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