Well I don't know what's up with these graphics, but even without perfect alignment of them, you can get the picture. We have a widespread severe weather outbreak beginning to unfold.
We have a Tornado Watch now for much of Missouri and Northern Arkansas. There are multiple Severe Thunderstorm Warnings there in the Midwest. The supercell thunderstorms are just getting their act together, but the threat for tornadoes is high and includes a threat for especially long-track, damaging tornadoes. Also a risk for very large hail up to the size of tennis balls and a risk for wind gusts up to 90 miles per hour. Now that is what you call a danger zone.
Locally our threat tonight should be between about Midnight and Daybreak tomorrow morning.
And this is a dicey threat compared to tomorrow's "main event". Which I'll cover in a separate post when I repost the SPC's Day 2 Outlook.
But for now let's focus on tonight's threat.
We could see damaging winds and large hail areawide. Far Northeast Alabama like around Rainsville or Fort Payne might have a more marginal threat of it. But most of us have the basic 15% threat for large hail and damaging winds. Now this hail should be more the size of quarters and the winds more like 60 mph gusts or so, not as bad as what they are expecting in Missouri and Arkansas over the next few hours. By the time the storms get here, they may have weakened considerably. But we could still have some issues.
Yesterday and many days lately I went into a ton of detail analyzing different model output for different severe weather parameters. Now the event is so close that I'm just mostly going to pass along the forecasts, watches, and warnings from the people who get paid to analyze this 24/7 at the Storm Prediction Center. They are thinking far Northwest Alabama might have a little of an enhanced hail threat, so in those hatched areas and nearby, some supercell thunderstorms might be able to sustain with more like golfball-sized hail. Notice that risk includes Western Tennessee and is close enough to Waynesboro, also stretches back through Northern Mississippi and actually Central MS too.
The threat for particularly damaging winds so more like 70-80 mph instead of 60 mph stretches through about the midpoint of Tennessee in this latest outlook and clips the Northwest corner of Alabama, but is not thought to be so much a threat further to the South, in West Central Alabama near the MS state line, like the enhanced hail threat is.
And the main thing on everybody's mind: The tornado threat. Unfortunately, along and West of I-65, we do have about a 10-15% probability of a tornado within 25 miles of any given point tonight. And these storms may be able to sustain as supercells enough to produce some fairly significant damage. When you see that hatched area, it means a good chance of a tornado that would have to be rated E/F-2 or higher. Most tornadoes only do enough damage to merit a rating of E/F-0 or F-1. And as you get East of I-65, places like Huntsville down to Guntersville and Arab, up to places like Fayetteville, TN, they are outlooked for the standard 5% chance of isolated tornadoes, no hatching to let them know of a more significant threat. And as you get into far Northeast Alabama, Jackson and Dekalb Counties, up around Fort Payne or Scottsboro, it's more of a minimal 2% tornado risk. By the time the storms get there, many of them will probably have weakened below severe limits. The air will get stabler tonight as you go farther to the East.
But Northwest Alabama and about the Western half of Southern/Middle Tennessee, definitely be prepared for the possibility of a tornado tonight. And we could see a couple tornadoes that are stronger than average in this setup, even though it's happening in the dark hours.
I don't like all this sunlight we've gotten today. Usually it's a good thing this time of year, but the warmth is likely to keep our air more unstable for tonight's event, at least over West/Northwest Alabama.
Another thought: Some people have to drive overnight during these hours. Now if you're at home, you just need a weather radio on alert with battery backup, or wireless emergency alerts enabled on your cell phone. So that you can wake up if need be for a Tornado Warning.
And make sure the phone's batteries are charged, it's not in a do-not-disturb or sleep mode.
But some people are driving trucks, maybe from other states. And some people have to get up very early to commute to work in the morning, when it's still dark.
So if you'll be driving during this event, try to plan somewhere you could pull over, like a truck stop or an all-night gas station, along your route. If a tornado is coming, you don't want to be caught in a vehicle, just like you wouldn't want to be caught in a mobile home tonight.
I know someone who left her mobile home to go stay with some family in Mississippi, in site-built house tonight. And that's what you have to do. Plan ahead. Be able to get to a sturdy house or other strong building for shelter before a violent storm is bearing down on you.
During a tornado, you need to shelter in a small room or hallway on the lowest floor, near the center of the building, away from any windows. And cover your body, especially your head, as best you can.
SPC AC 141958
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0258 PM CDT Fri Mar 14 2025
Valid 142000Z - 151200Z
...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS THE LOWER/MID
MISSISSIPPI VALLEY INTO THE LOWER OHIO VALLEY...
...SUMMARY...
A regional outbreak of severe thunderstorms is likely this afternoon
through tonight across parts of the Lower/Mid Mississippi Valley and
portions of the Lower Ohio Valley and Mid-South. Numerous tornadoes,
several of which could be strong to intense, widespread severe gusts
ranging from 60 to 100 mph, and scattered large hail up to baseball
size all appear likely.
...20z Update...
Widespread significant severe weather remains likely this afternoon
through tonight over much of the MS Valley and parts of the
Southeast.
An intense, negative-tilt upper trough and 120 kt mid-level jet will
rapidly eject northeastward over the central Plains through the day.
An associated deep surface low over western KS will continue to
intensify as it lifts east/northeast tonight. Initial updrafts along
a bent back dryline from northeastern KS, far eastern OK, and
western MO will spread northeastward into a warm and rapidly
moistening air mass over the MO Valley. While initial dewpoints are
quite limited, (40s F) very steep low and mid-level lapse rates and
a rapid surge of low-level moisture is likely later this
afternoon/evening. A broken line of initially high-based storms will
quickly spread eastward within very strong tropospheric flow.
Efficient downward momentum transport will support widespread
damaging gusts, potentially as high as 80-100 mph.
Ahead of these storms, low-level dewpoints should rapidly surge into
the 50s and low 60s F. Lowering cloud bases, and very strong mid and
low-level shear will allow for a few semi-discrete/embedded
supercells to form/mature over eastern MO, southern IA, western IL
and northern AR. A tornado threat (some strong to intense), is
likely to develop with these storms through the late afternoon and
evening hours, along with a continued risk for damaging winds and
large hail.
Farther south over parts of the ArkLaMiss and southwest TN,
scattered storms are expected to evolve within a strong low-level
warm air advection regime and ahead of the Pacific front. Dewpoints
in the mid 60s F will quickly lift northward over northern LA,
southern AR, into central MS. While forcing for ascent is likely to
be more nebulous, strong low-level flow within a 45-60 kt low-level
jet will support significant hodograph enlargement and sufficient
moisture/buoyancy for strong supercells. Recent CAM guidance has
come into better agreement on the positioning/timing of a cluster of
likely supercells evolving across northern LA and west-central MS
later this evening. Given the intensifying wind fields, and STP
environment of 3-4, strong tornadoes appear more likely through the
evening and into the overnight hours. Given increased confidence in
the development of intense supercells, have adjusted the Moderate
area farther south and west over MS/LA/AR.
..Lyons.. 03/14/2025
.PREV DISCUSSION... /ISSUED 1130 AM CDT Fri Mar 14 2025/
...Synopsis...
Water-vapor imagery late this morning indicates a powerful and
negatively tilted mid/upper-level shortwave trough over the southern
High Plains. An intense mid-level jet (with winds of 100-115+ kt at
500 mb) will continue to round the base of the trough, and quickly
eject northeastward across OK and eastern KS this afternoon. This
mid-level jet will move over parts of the mid MS Valley and Midwest
this evening and tonight in tandem with the northeastward-advancing
shortwave trough. Strong ascent aloft associated with both of these
features will overspread portions of the central CONUS as a deep
surface cyclone develops northeastward from the central High Plains
into the Upper Midwest this afternoon through tonight. In the low
levels, a dryline will surge eastward across the southern/central
Plains through the day, eventually arcing from the low southeastward
into the Ozarks. A large area of significant severe potential
remains evident across parts of the lower/mid MS Valley into the
Midwest and Mid-South.
...Mid Mississippi Valley into the Midwest and Mid-South...
Ample diurnal heating is expected through this afternoon ahead of
the cyclone, with elevated convection already occurring across parts
of eastern OK into southeast KS and southwest MO. More robust,
surface-based thunderstorms will likely develop by early/mid
afternoon (18-21z) along/east of the dryline from parts of eastern
NE southward into eastern KS/western MO, as a southerly low-level
jet attempts to bring shallow boundary-layer moisture northward into
the mid MS Valley and vicinity. The northern portion of this
convection will be oriented more orthogonal to the ejecting
mid-level jet, and current expectations are for quick upscale growth
into a fast northeastward-moving band, posing a risk for widespread
severe/damaging winds as this activity moves into IA and towards the
MO/IA/IL border region. Given the strength of the low/mid-level flow
and presence of steep lapse rates aloft, along with a well-mixed
boundary layer, intense thunderstorm straight-line gusts peaking
locally in the 80-100 mph range are possible with the stronger
cores/inflections in the band as it matures and moves across parts
of the mid MS Valley, and eventually into the southwestern Great
Lakes this evening through tonight.
Additional, potentially more discrete, severe thunderstorms will
develop this afternoon farther southeast along the wind shift into
central/eastern MO, generally on the northern periphery of somewhat
better low-level moisture from southeast MO southward into the
Mid-South. Stronger high-level flow and ample deep-layer shear over
these will likely promote at least semi-discrete supercells. Latest
model guidance, including various convection-allowing HREF members,
suggest scattered supercells developing late this afternoon and
evening as far south as the MS/AR/TN border region. Have nudged
severe probabilities and the corresponding SLGT/ENH/MDT westward a
little in western/central MO to account for a slightly earlier
initiation. Various NAM/RAP forecast soundings strongly favor
intense supercells capable of large to very large hail (up to 2-3
inches in diameter), and potentially multiple strong to intense
tornadoes this evening as effective SRH rapidly increases in tandem
with a southerly low-level jet strengthening to 50-65+ kt. This
substantial severe threat is expected to continue eastward overnight
into parts of the lower OH Valley/Midwest, before convection
eventually outpaces the low-level moisture return and weakens.
...Lower Mississippi Valley...
Large-scale forcing for ascent appears a bit more nebulous/weak
farther south into the lower MS Valley. Still, the 12Z suite of
guidance shows some potential for surface-based thunderstorms
developing by late this afternoon across the ArkLaMiss region. While
the stronger low/mid-level flow and forcing are expected to remain
to the north of this region, greater low-level moisture and related
instability will be present. This favorable thermodynamic and
kinematic environment will support supercells, with associated
threat for large to very large hail, damaging winds, and tornadoes.
Some of tornadoes could be strong this evening with any sustained
supercells, especially across central MS and vicinity. Have expanded
the ENH to account for this potential, and consideration was given
to expanding the MDT southward into central MS as well. But, there
is still some uncertainty with overall thunderstorm coverage.
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