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Severe WX Severe Weather Threat - February 15-16, 2023

I think there should be a hatched 10% tornado risk in the elongated 5% risk shown on the nadocast. The thunderstorm coverage looks robust in this region and I could see the occurrence of a significant long track tornado.

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Interesting for North Alabama

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.THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF THE LOWER MISSISSIPPI VALLEY AND WESTERN TENNESSEE VALLEY...

...SUMMARY...
Widely scattered severe thunderstorms are possible over parts of
Texas and Oklahoma beginning late in the day and into the evening on
Wednesday. A severe threat will also develop overnight over the
lower Mississippi Valley/Mid-South region, with a tornado risk.

...Eastern OK/North-Central TX to the Mid-South...

Late-evening satellite imagery depicts a well-defined upper low
digging southeast into northern AZ. This feature is forecast to
shift into the southern Rockies by mid day as a 110kt 500mb jet
translates across the desert southwest toward the southern High
Plains. With time this feature will advance into eastern KS allowing
the trough to become more positive tilted as it moves into the
central Plains. This evolution will maintain broad southwesterly
flow across lower latitudes, including the Mid-South region. Of
particular concern will be the development of a pronounced LLJ
across the lower MS/TN Valley, especially during the latter half of
the period when a marked increase is expected (in excess of 60kt).
More appreciable mid-level height falls will remain north of the
higher-buoyancy air mass, thus low-level warm advection will likely
prove instrumental in the majority of supercell development through
the period.

At 05z, a narrow band of strongly-forced convection is observed
along the front over AZ. Otherwise, most of the southern states are
convective free with strong capping. Low-level trajectories favor
Gulf air mass advancing inland across the lower MS Valley, and mid
60s surface dew points are well established at this time over much
of the upper TX Coast and LA. Latest guidance suggests this air mass
will easily advance north into AR/western TN Valley later today;
however, convective development will likely remain suppressed until
the latter half of the period when the LLJ intensifies in response
to the approaching short wave.

Upstream, strong boundary-layer heating across the southern High
Plains will result in very steep surface-3km lapse rates from the
southern TX Panhandle into western OK/northwest TX. It appears this
steep lapse rate plume will overspread the northwestern portions of
return moisture across south-central OK/north-central TX, just ahead
of the front/dry line. As temperatures warm into the lower 70s
capping should weaken and scattered convection is expected to
develop. Forecast soundings favor supercell development and this
activity should spread east during the evening hours with an
attendant threat for all hazards.

Downstream, LLJ will increase across LA into western TN from late
afternoon into the evening. Steep mid-level lapse rates will
overspread this region as 3km capping gradually weakens. As the cap
weakens, isolated discrete supercells are expected to evolve within
a moistening, warm advection regime. ESRH values in excess of 300
m2/s2, along with steep lapse rates, and modest instability favor
severe supercells capable of producing tornadoes, possibly strong. A
corridor of supercells may ultimately evolve along an axis from
southeast AR into western TN, during the latter half of the period,
as the cold front will not advance east of the MS River prior to
sunrise. Warm advection should be the primary forcing mechanism for
this activity, thus episodic bouts of severe are possible.
Click to expand...
 
.THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM
MISSISSIPPI AND ALABAMA NORTHWARD INTO THE OHIO VALLEY...

...SUMMARY...
Widely scattered severe thunderstorms are likely from the central
Gulf Coast states northward into the Ohio Valley on Thursday and
Thursday evening. Several tornadoes are possible over Mississippi
and Alabama, including the risk for strong tornadoes.

...Synopsis...
A powerful mid-level trough will gradually move east from the
central Great Plains/Desert Southwest to the Great Lakes/southern
Great Plains during the period. A surface low initially over
southern MO will develop northeast to central IN by early-mid
afternoon, and subsequently to the Lower Great Lakes during the
overnight. A cold front attendant to the low will sweep eastward
across the OH Valley and the central Gulf Coast states. A surface
boundary over the OH Valley will advance north as a warm front as
the low develops east-northeast along it.

...Central Gulf Coast states...
Showers and thunderstorms will likely be ongoing early Thursday
morning near a cold front over AR/LA with a marginal risk for severe
storms accompanying this early activity. Southerly low-level flow
will advect richer moisture into the coastal plain, while some
heating amidst cloud breaks acts to destabilize the airmass. Models
suggest diurnal thunderstorm development in the warm sector during
peak heating, to the east of the front over parts of MS and
spreading into AL. Large clockwise-curved and elongated hodographs
will favor supercells with the more robust updrafts. Several
tornadoes (some strong) are possible and may focus in a mesoscale
corridor where the greatest buoyancy (1000 J/kg MLCAPE) is indicated
by the models, over parts of MS east into west-central AL during the
early evening. By mid evening, lessening instability due to
nocturnal cooling and storms consolidating into more linear modes
indicate the severe risk (i.e., damaging gusts/tornado) will begin
to wane, as the storms move east into eastern AL/western GA/FL
Panhandle.

...OH Valley into the Lower Great Lakes...
Showers and thunderstorms located within a strong WAA regime will be
widespread across the lower OH Valley at daybreak Thursday. An
isolated risk for strong to severe thunderstorms may continue into
the early part of the morning, before this activity quickly moves
northeast and away from the greater instability by midday. A
rejuvenation in storms is forecast over parts of IN/KY and spreading
east-northeast into OH during the afternoon into the evening.
Forecast soundings over west-central OH southwestward to the
Kentuckiana region show weak buoyancy but large hodographs and
strong speed shear in the lowest 3-6 km. It is uncertain whether a
few low-topped supercells will develop within this area of
potentially greater buoyancy, but convective coverage is forecast to
increase during the afternoon as storms quickly move east-northeast
on the northern periphery of a warm sector. Damaging gusts will be
the primary hazard, but some tornado risk may develop with either
supercells and/or line segments, given the moist boundary layer
co-located with strong shear. This activity will likely reach
eastern OH into the lower Great Lakes region after sunset, but
forecast soundings imply these storms may remain surface based, and
perhaps the risk for damaging gusts continues into the late evening.
Click to expand...
 
Day 1 outlook kind of concurs with thoughts of the last couple days and associated CAM runs.

WAA-driven nocturnal CI is always such a crapshoot. High Forecasted Convective Amplification Deficiency potential, but also potential for something very dangerous should a couple of cells get rooted and become sustained.

Got a long day of monitoring trends ahead. Definitely not one of those "call Forecasted Convective Amplification Deficiency if nothing fires by sundown" type of setups.
 
CheeselandSkies said:
Day 1 outlook kind of concurs with thoughts of the last couple days and associated CAM runs.

WAA-driven nocturnal CI is always such a crapshoot. High Forecasted Convective Amplification Deficiency potential, but also potential for something very dangerous should a couple of cells get rooted and become sustained.

Got a long day of monitoring trends ahead. Definitely not one of those "call Forecasted Convective Amplification Deficiency if nothing fires by sundown" type of setups.
Click to expand...
Cam models started pick up on super cells last evening , been pretty Consistent showing this. Especially back in southeast Arkansas into sw Tennessee . It was a no brainer spc upgraded to enhanced in these areas over night . Besides lower level jet will
Be crazy among over night in the 10
Percent hatched . Definitely worth watching
 
CheeselandSkies said:
Day 1 outlook kind of concurs with thoughts of the last couple days and associated CAM runs.

WAA-driven nocturnal CI is always such a crapshoot. High Forecasted Convective Amplification Deficiency potential, but also potential for something very dangerous should a couple of cells get rooted and become sustained.

Got a long day of monitoring trends ahead. Definitely not one of those "call Forecasted Convective Amplification Deficiency if nothing fires by sundown" type of setups.
Click to expand...
NWS BMX said the same thing: How today goes really comes down to the smaller details they won’t know about until the day of.

Tricky Dixie.
 
It's always that interstate 20/59 corridor lol for tornadoes. I'd watch for a possibly higher bump to 30% in that same corridor possibly depending on how the mesoscale features evolve overnight tonight into tomorrow.
 
UncleJuJu98 said:
It's always that interstate 20/59 corridor lol for tornadoes. I'd watch for a possibly higher bump to 30% in that same corridor possibly depending on how the mesoscale features evolve overnight tonight into tomorrow.
Click to expand...

They won't bump to 30% for tornadoes, that would be a high risk.
 
CheeselandSkies said:
They won't bump to 30% for tornadoes, that would be a high risk.
Click to expand...
I thought 45% was high risk. And 30% was moderate?

It makes it a high risk if it's a 30% hatched but not just a regular 30%.

Yeah I doubt they'll bump it to a high risk cause I doubt it would be anything other than a hatched area for the higher potential.
 
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