Convective Outlook

SPC 1730Z Day 2 Outlook
Day 2 Outlook Image

Day 2 Convective Outlook  
NWS Storm Prediction Center Norman OK
1224 PM CDT Sun Apr 11 2021

Valid 121200Z - 131200Z


Isolated severe thunderstorms are possible in the Texas Hill Country
on Monday with a threat for large hail and severe wind gusts.

A few areas of mid-level low pressure will be present across the
northern Plains and Great Lakes Monday morning. These low pressure
areas will shift eastward/southeastward through the day. A strong
mid-level jet will dive southward along the West Coast through the
day Monday and act to amplify the western CONUS trough. In addition,
a weak shortwave is expected to eject from this broader trough
Monday afternoon across portions of Texas. At the surface, a cold
front will sink southward across Texas through the day. Some severe
storms may form on this cold front Monday afternoon/evening with a
threat for large hail and severe wind.

...Texas Hill Country...
Low-level flow off the Gulf of Mexico will transport moisture
northwestward Monday morning and afternoon. Surface dewpoints are
expected to increase to the low to mid 60s by mid to late afternoon
with temperatures in the low to mid 80s. This will likely result in
2000+ MLCAPE ahead of a southward moving cold front. A weak
shortwave/height falls aloft combined with convergence along this
front may provide enough forcing for a few strong to severe storms
Monday afternoon/evening. Moderate to strong instability combined
with around 50 knots of effective shear will provide an environment
favorable for supercells with the potential for large hail and
damaging winds. The southward sagging nature of the cold front could
undercut the storms and limit storm longevity, especially on the
northern portions of the marginal risk, but steep mid-level lapse
rates would still support elevated convection and a hail threat.
Additional storms may form in an upslope regime near Del Rio and
move off the terrain for a few hours in the evening before
encountering a capped airmass with eastern extent. Questionable
storm coverage is the primary mitigating factor to a higher risk
category at this time, but if more storms appear likely (such as
suggested by the 12Z HRRR and NSSL WRF), a slight risk may be
warranted in later outlooks.

..Bentley/Gleason.. 04/11/2021

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Updated 11 April 2021 | 12:27 pm

SPC 1630Z Day 1 Outlook
Day 1 Outlook Image

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
1129 AM CDT Sun Apr 11 2021

Valid 111630Z - 121200Z


Damaging winds, a tornado or two, and isolated large hail are
expected this afternoon across central Florida.  The threat for a
few damaging gusts will also shift southward into south Florida
later this afternoon/evening.

...Central/south FL this afternoon/evening...
A large cluster of thunderstorms that formed early this morning
across the northeast Gulf of Mexico is evolving into a bowing MCS as
it moves onshore near Tampa.  The storms will likely move along an 
outflow boundary across central FL through the day, with the storms
forcing the outflow southward with time.  Surface heating and
increases in low-level moisture south of the boundary, along with 50
kt west-southwesterly midlevel flow, will support the threat for
swaths of damaging gusts with the bowing segments.  A tornado or two
may also occur with embedded circulations where the bowing segments
interact with the east-west oriented outflow boundary.

The threat for at least isolated damaging winds will shift southward
with time along the outflow boundary, spreading into south FL this

...Eastern NC into the Mid-Atlantic this afternoon/evening...
A lead shortwave trough is rotating northeastward over the
Mid-Atlantic as of midday, with little forcing for ascent (or weak
subsidence) in its wake.  Given surface heating and lingering
low-level moisture along and ahead of a cold front, a few storms may
still develop this afternoon, with the more probable area from VA
into south central PA.  There will be marginally sufficient vertical
shear and buoyancy for a low-end threat for damaging winds and/or
large hail with the strongest storms this afternoon/evening.

..Thompson/Guyer.. 04/11/2021

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Updated 11 April 2021 | 11:33 am