• Welcome to TalkWeather!
    We see you lurking around TalkWeather! Take the extra step and join us today to view attachments, see less ads and maybe even join the discussion.
    CLICK TO JOIN TALKWEATHER

Severe Weather Threat - Jan 11-12th, 2024

Last edited:
MattW said:
Has nadocast even been updating recently? The latest post I see is March 30, 2023.
Click to expand...
I don't understand how Twitter sorts tweets either, you'd think "newest first" would be the default, but naturally...

And I should also correct myself to say Nadocast technically does have its own website - if one would enjoy digging through their data repository...
 
Today:

SPC.jpg

SPCTOR.jpg
THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE ARK-LA-TEX...

...SUMMARY...
Severe thunderstorms, associated with tornadoes, wind damage and
isolated large hail, are likely to develop across parts of the
Ark-La-Tex this evening into the overnight. A severe threat is also
expected to develop further south across parts of east Texas and
Louisiana.

...Ark-La-Tex...
An impressive upper-level system will translate quickly eastward
through the Desert Southwest today, reaching the southern Plains
this evening. Within the base of the trough, a 100 to 120 knot
mid-level jet will move through west Texas this evening, as the nose
of the jet overspreads the Ark-La-Tex. Ahead of the system, moisture
will return northward across east Texas and Louisiana, with the nose
of the moist sector reaching southern Arkansas by early evening. In
response, a pocket of instability is forecast to develop across
southeast Oklahoma, southwest Arkansas and northeast Texas, where
convective initiation is expected during the mid evening.
Thunderstorms are likely to rapidly increase in coverage during the
late evening. Most hi-resolution models develop a line of strong to
severe storms and move the line slowly eastward across southwest
Arkansas and far northeast Texas during the early overnight period.
As lift and shear increase due to the approach the mid-level jet,
conditions are expected to become favorable for severe storms.

Model forecast soundings across the Ark-La-Tex by 06Z have surface
dewpoints near 60 F as far north as the Louisiana and Arkansas state
line. Even so, MLCAPE should reach the 500 to 1000 J/kg range at the
northern edge of the moist sector by late evening. Very strong lift
associated with the exit region of the mid-level jet combined with
low LCL heights and strong low-level shear should be favorable for
supercells embedded in the line, and with the more discrete cells
that develop ahead of the line. Some forecast soundings suggest that
700-500 mb lapse rates will approach 8 C/km across the northern part
of the warm sector. Although the large-hail threat should remain
isolated, the steep mid-level lapse rates should be sufficient for a
significant-hail threat. Hailstones of greater than 2 inches in
diameter will be possible a few hours after cells initiation, as the
storms mature. In addition, 0-3 km storm-relative helicity is
forecast to peak near 400 m2/s2 in and just north of the Shreveport
vicinity. This is also expected to support a tornado threat with the
more intense supercells. Any supercell that can persist and become
dominant may be able to produce a significant tornado or two. A
wind-damage threat will also likely develop along the line of
storms, with the greatest potential located across Ark-La-Tex, where
an Enhanced risk has been introduced.

...East Texas/Louisiana...
Further south into east Texas and Louisiana, storm coverage is
expected to be more isolated from the late evening into the
overnight period. In this area, to the south of the mid-level jet
axis, instability is not expected to be as strong. Also, lift may
not be quite as concentrated. For this reason, supercell development
is expected to remain more isolated. Any cell that can become
organized and sustained could produce isolated large hail, wind
damage and a tornado or two. The severe threat should more isolated
with southward extent, with only a marginal severe threat expected
near in the coastal sections of southeast Texas and southern
Louisiana.
Click to expand...
 
Friday:

.THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FRIDAY
AFTERNOON AND INTO FRIDAY EVENING ACROSS PARTS OF EAST CENTRAL AND
SOUTHEASTERN ALABAMA...MUCH OF CENTRAL GEORGIA AND SOUTH CAROLINA
INTO SOUTHERN NORTH CAROLINA...

...SUMMARY...
Severe thunderstorms, with potential to produce high winds and a few
strong tornadoes, are possible across parts of the Southeast Friday
through Friday evening.

...Discussion...
There appears little substantive change in the latest available
ECENS/ECMWF and GEFS concerning the forecast evolution for this
period. Strong surface cyclogenesis is likely to proceed Friday
across the Mississippi Valley through Atlantic Seaboard, as a
vigorous supporting short wave trough pivots northeast of the
southern Great Plains. It still appears that the center of the
growing cyclone will undergo a period of rapid deepening across the
lower Ohio Valley during the day, including minimum surface
pressures falling on the order of 15-20 mb in a 12 hour period,
though the 00Z NAM/03Z RAP take a track to the northwest of the
other guidance into the Great Lakes region through late Friday
night.

Regardless, associated strengthening of deep-layer wind fields
probably will including a developing swath of 90-120+ kt
cyclonic/southwesterly flow at 500 mb across the lower Mississippi
Valley, through portions of the Northeast and Mid Atlantic by the
end of the period. In the 850-700 mb layer, 50-90 kt south to
southwesterly flow is generally forecast to overspread the inland
advancing warm sector.

There remains some uncertainty concerning just how expansive of an
unstable warm sector may develop, with perhaps low-level warming and
moistening becoming sufficient, in the presence of strong forcing
for ascent, for weak boundary-layer destabilization northeast of the
lower Mississippi Valley through parts of the Tennessee and lower
Ohio Valleys during the day.

More substantive low-level moistening is probable off the north
central/northeastern Gulf of Mexico, into the eastern Gulf through
south Atlantic coast states. However, with the mid-level cold pool
forecast to shift north of this region, relatively warm layers
aloft, even in advance of mid-level subsidence warming nosing
east-northeastward across coastal areas, could inhibit
destabilization.

More problematic, concerning the severe weather potential, the NAM
and Rapid Refresh forecast soundings are slow to erode the initially
cool boundary layer, and maintain at least a shallow near surface
stable layer. If this verifies, convective potential will probably
be mitigated. However, a corridor of strong surface pressure falls
still appears likely to develop across the Southeastern Piedmont,
from Alabama through the Carolinas midday Friday through Friday
evening, near the southern periphery of the mid-level height falls.
Associated forcing may contribute to more rapid modification of the
boundary-layer, in the presence of an environment otherwise becoming
conditionally supportive of significant severe weather potential.

Strong to severe thunderstorm development, initiating Thursday night
across the southeastern Great Plains into the lower Mississippi
Valley, may be ongoing at the outset of the period, spreading
east-northeast of the Mississippi River Friday morning, before
perhaps weakening. Renewed thunderstorm intensification is then
expected near/ahead of a developing pre-frontal dryline structure
developing across east central/southeastern Alabama by early
afternoon, particularly near where it intersects a strengthening
frontal zone across the Piedmont. This probably will be maintained
while spreading east-northeastward across Georgia into the Carolinas
by late Friday evening.

Although the evolution of an organized convective cluster still
appears possible, discrete supercell development may remain the
primary convective mode, accompanied by a risk for strong tornadoes.

..Kerr.. 01/11/2024
Click to expand...


SPC3.jpg

SPCTOR3.jpg
 
“More problematic, concerning the severe weather potential, the NAM and Rapid Refresh forecast soundings are slow to erode the initially cool boundary layer, and maintain at least a shallow near surface stable layer. If this verifies, convective potential will probably be mitigated.”

So in other words….?
 
KevinH said:
“More problematic, concerning the severe weather potential, the NAM and Rapid Refresh forecast soundings are slow to erode the initially cool boundary layer, and maintain at least a shallow near surface stable layer. If this verifies, convective potential will probably be mitigated.”

So in other words….?
Click to expand...
Conditional threat that will be impossible to have high confidence in before we get to the day of and have actual observations of the environment we're going to have to work with in terms of instability/moisture because right now those things are a big question mark (so basically the same thing they've been saying all along).

More specifically, what they're saying is that none of those crazy hodographs and SRH values matter if the boundary layer is stable because then there's nothing to translate that shear down to the surface. You don't get much help from the sun in January in terms of destabilizing the boundary layer, so it's going to be almost entirely contingent on warm/moist advection and there's still a lot of question marks about how far north that'll get (especially since the models handle that poorly in the cool season in general). Stable boundary layer = storms stay elevated (or don't form at all) and you get what we had that one day last year (3/3 maybe?) where you had this absurd parameter space but there was a layer of warm air aloft that snuffed it out.
 
SREF continues to zero in on areas from MS to the Carolinas, and also notes that cold core-ish threat up north. CAMs continue to show the same presentation, with a very marginal warm sector to work with. A bit surprised the SPC remains as bullish as they are, though they explain their reasoning well. A real head-scratcher, though; definitely not envying the SPC. Continues to feel like a setup which may either give us some pretty nasty surprises or a benign outbreak of rain showers.
1704980074653.png1704980077687.png1704980095534.png
1704980149905.pngrefcmp_uh001h.us_se.png
...Discussion...
There appears little substantive change in the latest available
ECENS/ECMWF and GEFS concerning the forecast evolution for this
period. Strong surface cyclogenesis is likely to proceed Friday
across the Mississippi Valley through Atlantic Seaboard, as a
vigorous supporting short wave trough pivots northeast of the
southern Great Plains. It still appears that the center of the
growing cyclone will undergo a period of rapid deepening across the
lower Ohio Valley during the day, including minimum surface
pressures falling on the order of 15-20 mb in a 12 hour period,
though the 00Z NAM/03Z RAP take a track to the northwest of the
other guidance into the Great Lakes region through late Friday
night.

Regardless, associated strengthening of deep-layer wind fields
probably will including a developing swath of 90-120+ kt
cyclonic/southwesterly flow at 500 mb across the lower Mississippi
Valley, through portions of the Northeast and Mid Atlantic by the
end of the period. In the 850-700 mb layer, 50-90 kt south to
southwesterly flow is generally forecast to overspread the inland
advancing warm sector.

There remains some uncertainty concerning just how expansive of an
unstable warm sector may develop, with perhaps low-level warming and
moistening becoming sufficient, in the presence of strong forcing
for ascent, for weak boundary-layer destabilization northeast of the
lower Mississippi Valley through parts of the Tennessee and lower
Ohio Valleys during the day.

More substantive low-level moistening is probable off the north
central/northeastern Gulf of Mexico, into the eastern Gulf through
south Atlantic coast states. However, with the mid-level cold pool
forecast to shift north of this region, relatively warm layers
aloft, even in advance of mid-level subsidence warming nosing
east-northeastward across coastal areas, could inhibit
destabilization.

More problematic, concerning the severe weather potential, the NAM
and Rapid Refresh forecast soundings are slow to erode the initially
cool boundary layer, and maintain at least a shallow near surface
stable layer. If this verifies, convective potential will probably
be mitigated. However, a corridor of strong surface pressure falls
still appears likely to develop across the Southeastern Piedmont,
from Alabama through the Carolinas midday Friday through Friday
evening, near the southern periphery of the mid-level height falls.
Associated forcing may contribute to more rapid modification of the
boundary-layer, in the presence of an environment otherwise becoming
conditionally supportive of significant severe weather potential.

Strong to severe thunderstorm development, initiating Thursday night
across the southeastern Great Plains into the lower Mississippi
Valley, may be ongoing at the outset of the period, spreading
east-northeast of the Mississippi River Friday morning, before
perhaps weakening. Renewed thunderstorm intensification is then
expected near/ahead of a developing pre-frontal dryline structure
developing across east central/southeastern Alabama by early
afternoon, particularly near where it intersects a strengthening
frontal zone across the Piedmont. This probably will be maintained
while spreading east-northeastward across Georgia into the Carolinas
by late Friday evening.

Although the evolution of an organized convective cluster still
appears possible, discrete supercell development may remain the
primary convective mode, accompanied by a risk for strong tornadoes.

..Kerr.. 01/11/2024
Click to expand...
 
Clancy said:
SREF continues to zero in on areas from MS to the Carolinas, and also notes that cold core-ish threat up north. CAMs continue to show the same presentation, with a very marginal warm sector to work with. A bit surprised the SPC remains as bullish as they are, though they explain their reasoning well. A real head-scratcher, though; definitely not envying the SPC. Continues to feel like a setup which may either give us some pretty nasty surprises or a benign outbreak of rain showers.
Click to expand...
I can understand the argument that, in a situation where there's a lot of uncertainty, maintaining a consistent message makes sense until you have concrete justification (i.e. real-time obs) to change what you're saying. Less confusing for normal people who aren't model-watching weenies.
 
warneagle said:
I can understand the argument that, in a situation where there's a lot of uncertainty, maintaining a consistent message makes sense until you have concrete justification (i.e. real-time obs) to change what you're saying. Less confusing for normal people who aren't model-watching weenies.
Click to expand...
Definitely; it'd be frustrating to the average joe if they were flipping back and forth on this. The social implications of public messaging are as complicated as the science behind it.
 
Seems this has trended back toward a pretty spatially limited unstable warm sector on both the north edge (distance inland from the Gulf coast) and E-W breadth for supercell running room; much like Monday night-Tuesday. Like we saw then, there could still be some nasty, dangerous stuff where the instability does develop, but I wouldn't expect it much further inland than about Dothan and Enterprise in Alabama unless things drastically change in the short term.
 
CSU not showing a hatched area anymore, which is some good news

severe_ml_day2_all_gefso_011312.png
 
Yeah, this event is looking extremely conditional. Not at all like Tuesday's event in that regard.

Here's the Hazcast Tornado probabilities at 12z Friday, which is interesting if it verifies:

1704981874754.png

Then, further south a little later:

1704982017994.png

1704982135750.png
1704982151502.png
 
Still remember the march 3rd 2023 event the night prior it went heckin chonkers forecasting the next day with supercell printer after not doing it the entire time the hrrr had it in view. And then blipped away. Kindve similar setup.

Of course there wasn't a bunch of supercells with tornadoes but SPC went with a hatched 10% if I remember correctly

May have been another one but similar in showing no rooted storms and then going insane lol

So I'm waiting for that one run of the HRRR to go stupid lol
 
You must log in or register to reply here.
Back
Top