The Storm Prediction Center maintains the Level 3 Enhanced Risk level for severe thunderstorms for most of our area Sunday night into early Monday morning.
This is mainly a threat for damaging thunderstorm winds, with the threat for large hail looking marginal as the event gets closer. Since the better chance of supercell thunderstorms may stay to our Northwest. By the time the storms get here, they may have already formed a cluster or two, or if it's more the usual way things go, a squall line.
For most of us the chance of damaging thunderstorm winds is about 30%. In far Northeast Alabama it drops to about 15% of any one spot getting that within 25 miles of a given point. And places like Florence, Lawrenceburg, and Waynesboro have a 45% chance, basically a 50/50 chance of it.
The threat for large hail is thought to be marginal except for that same zone up around Florence, Lawrenceburg, and so on. It wouldn't surprise me if one or two spots ended up getting a storm that produced significant hail in spite of this outlook. Some of the guidance over the past few days has made it look like that's a possibility, just not a very high one. If it happens, should be isolated.
Most of us have a basic 2-5% risk for isolated tornadoes with this system. And that's enough to respect, though it's rather routine for this time of the year. That same zone that has a higher threat for damaging winds or large hail also has a 10% chance of a tornado, and note that this area is hatched. That means there is a greater risk of a tornado that comes out of a supercell thunderstorm and has a better chance of producing fairly significant damage. That zone includes Florence and also places like Lawrenceburg and Waynesboro, back to places like Tupelo.
But all of us need to respect the tornado threat as well as the severe thunderstorm wind/hail threat.
If you get a Tornado Warning, you need to move to a small interior room (or hallway) on the lowest floor of a sturdy house or other strong building, away from windows. Don't stay in a mobile home if a tornado is coming your way. If you can, cover your body in your shelter area from any falling or flying debris, especially protect your head and neck.
If you get a Severe Thunderstorm Warning, you need to at least move away from windows and electrical stuff until the storms have passed. Depending on the situation, sometimes it's wise to take precautions somewhat similar to what you would for a Tornado Warning. This is especially true if the warning carries a tag that says "Tornado: Possible" or "Particularly Dangerous Situation". The latter is sometimes issued for hurricane-force winds and/or very large hail in a severe thunderstorm. It doesn't always take a tornado to cause serious injury if precautions are not taken, and unfortunately, most people don't pay much attention to Severe Thunderstorm Warnings. Cell phones don't trip WEA for them unless they do carry that PDS tag.
A Tornado Watch just lets you know to get ready for severe weather over the next few hours. But no immediate action is needed.
Since this is an overnight event, the main thing is to have a reliable way to get the alerts. That is NOT an outdoor siren. A lot of people have died over the years because they expected a siren to wake them up.
On the other hand, Wireless Emergency Alerts on a cell phone has a good chance of waking you up.
So does a NOAA Weather Radio with battery backup (in case the power were to go out).
So does a service like WeatherCall.
And actually, if you prefer (or find that your nose is not exactly running money at the moment), so does a good radio station that you can sleep to that will cut in with an emergency alert tone before telling about the severe weather. The classical stations, 90.3 FM from Birmingham and 89.3 FM from Huntsville, both do this. And that emergency alert tone is a jarring contrast from all that soft classical music and the DJ's that sound like they've been under sedation, their tone of voice. I can tell you for sure that Live 95.5 FM in Cullman cuts in like this. And you might find the music less boring. But look, classical music is good to sleep by. And that tone will wake you up if you can't afford a weather radio. If you have to resort to this, please also check your cell phone to make sure WEA is enabled and the phone is not in a "sleep" or "do not disturb" mode. So then you've still got two layers of protection, reliable ways to get woke up if you need to be.
And if a tornado is coming, you need to be.
If you were to know someone in the path of a tornado during this overnight event, text them first. If you don't get a response within a minute or two, give them a call. It's better to have a pissed-off friend or loved one who was able to take shelter than to have a friend who slept peacefully right up until they got hurt by a damaging storm.
This is looking more like a damaging wind event, whether it's more of clusters (MCS) or a squall line (QLCS). But we do have to respect the tornado threat as well, regardless of whether more isolated supercell thunderstorms are able to sustain by the time the system moves into North Alabama/Southern Middle Tennessee. Even those supercells within a cluster or line, or the "quick spinup tornadoes" can be dangerous if people don't know they are coming and don't do anything to take cover.
And it's sort of a trade-off that the more significant tornadoes tend to do more damage and carry a greater risk of harming more people, but the warnings are usually excellent, like people might have 10-15 or even 20 minutes or more to get to a safe place before the storm arrives. If it's an isolated supercell. But then the ones that only do average damage or are relatively "weak" can happen so quickly, sometimes lasting five minutes or less once they touch down. So people need to take cover quickly.
And with that, I'm calling it a night. Because we're likely in for a long one Sunday night.
SPC AC 300537
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1237 AM CDT Sun Mar 30 2025
Valid 301200Z - 311200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
THROUGH TONIGHT ACROSS MUCH OF SERN IL...IN...WRN AND CENTRAL
OH...SERN MO...CNTRL AND ERN AR...KY...TN...NWRN AL...NRN AND CNTRL
MS...NRN LA...NERN TX...
...SUMMARY...
Thunderstorm development is likely to become widespread across the
Ohio Valley southwestward through the Tennessee and lower
Mississippi Valleys this afternoon into tonight. Initially, this
activity will pose a risk for large large hail. A few tornadoes are
also possible, before damaging wind gusts become the more prominent
potential severe hazard this evening into tonight.
...Discussion...
To the north of an intense, zonal jet across the southern
mid-latitude eastern Pacific, a significant mid-level low is
forecast to progress slowly eastward across the northeastern
Pacific, toward the Pacific Northwest coast, accompanied by a deep
occluded surface cyclone. This has been preceded inland by a series
of less prominent perturbations, a couple of which may be
consolidating into more notable larger-scale mid-level troughing to
the east-northeast of the southern Rockies.
Models continue to indicate that this evolving mid-level wave will
accelerate into a broadly confluent regime across the Ohio Valley
through lower Great Lakes region, between a significant short wave
trough digging across Manitoba/Ontario and downstream ridging
overspreading the St. Lawrence Valley/Northeast. Models suggest
that an associated surface low, likely initially over eastern Iowa
at the outset of the period, will continue an east-northeastward
migration into and across the Great Lakes, but it may not undergo
substantive further deepening until late this afternoon into tonight
across the lower Great Lakes into southeastern Ontario/southwestern
Quebec.
Trailing this cyclone, a notable cold front is forecast to progress
southeastward through the southern Great Plains, and eastward
through the mid/lower Mississippi Valley and middle Ohio Valley by
late tonight. The front will continue to be preceded by a
moistening southerly return flow, which may include surface dew
points increasing through the lower/mid 60s F as far north as
southern portions of the Great Lakes region, at least initially
beneath a remnant plume of elevated mixed-layer air emerging from
the high plains.
...Ohio Valley into southeastern Great Plains...
Models suggest that thermodynamic profiles will become supportive of
sizable conditional and convective instability, with a fairly broad
reservoir of CAPE in excess of 2000 J/kg evolving across the
southeastern Great Plains through lower Mississippi Valley, as far
north as the confluence with the Ohio River by late this afternoon.
Farther north, mixed-layer CAPE is likely to increase in excess of
1000 J/kg during the day, within a narrower corridor
across/north-northeast of the middle Mississippi Valley, where
mid/upper forcing for ascent is likely to initiate intensifying
thunderstorm activity by early to mid afternoon. This may include a
few supercells posing a risk for large hail and potential for a
couple of tornadoes, before convection tends to gradually
consolidate and grow upscale, accompanied by increasing risk for
damaging wind gusts.
This initial activity may be maintained northeastward and eastward
through much of the Ohio Valley by late this evening, before tending
to weaken while acquiring less unstable inflow. Meanwhile,
subsequent initiation of storms is likely southwestward ahead of the
cold front, across the lower Ohio Valley/Mid South toward the
Ark-La-Tex later this afternoon into this evening. It appears
possible that this may coincide with strengthening
lower/mid-tropospheric flow accompanying a trailing jet streak. And
a period of intensifying discrete supercell development might not be
out of the question, before activity tends to grow upscale into one
or more organizing clusters. Depending on how quickly this occurs,
there may be a conditional risk for a couple of strong tornadoes,
before damaging straight line winds, and perhaps brief tornadoes
with evolving near-surface meso vortices, becomes the more prominent
hazard southeastward into the Gulf Coast states overnight.
...Florida Peninsula vicinity...
HREF and NCEP SREF guidance indicates rather high probabilities for
thunderstorm development, as weak mid-level troughing overspreads
the peninsula today. Beneath modestly cool mid-level temperatures,
it appears that boundary-layer moisture will support moderate CAPE,
and thermodynamic profiles may become conducive to a few stronger
storms with small, melting hail contributing to potential for
localized damaging downbursts.
..Kerr/Weinman.. 03/30/2025
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