Hpdb301
Member
I'm not the best at reading soundings but the Cape in North Alabama after the 1st wave is outrageous! someone read this for me and give me the full scoop. Please!
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Severe Severe Threat April 5th-7th
- Thread starter Storm5
- Start date
Mason Dixon
Member
Excellent writeup, Bill Murray is really good at breaking systems down
Looks pretty impressive. 0-1km SRH is very supportive of tornadoes 1-3 is as well but having a higher value there would be really concerning. More than enough shear for organized convection. Overall certainly a sounding supportive of tornadoes and severe weather
ForsythSnow
Moderator
The cape looks insane, nearly 3500KJ is extreme. If I am looking at the sounding right, the environment will end up supporting hail. Not too much of an expert on sounding though.I'm not the best at reading soundings but the Cape in North Alabama after the 1st wave is outrageous! someone read this for me and give me the full scoop. Please!
Severe Thunderstorm Watch for Oklahoma, Missouri, and Arkansas.
It begins.
JHS
Member
Things begin to change rather quickly aft sunrise tomorrow as a
deepening sfc low advances toward the srn Midwest. An associated
upper low will swing a large area of vort energy into the base of
the trof which will create increasing ulvl difl flow over the FA
with pockets of energy traversing the flow. At the llvls...there are
sigfnt disagreements wrt the synoptic pattern. The NAM is developing
a moist/stable insitu wedge, which lasts throughout the period. This
is not supported by the other op models nor the ens guidance. Thus
the NAM will be treated as an outlier and will count on a good
amount of destabilization during the afternoon.
If they are right this threat will cover a larger area in GA, NC, and SC for a much longer time. A BIG concern will also of course be where the boundary would set up if the NAM turns out to be right. Areas near it would have an even better chance of getting a tornado.
deepening sfc low advances toward the srn Midwest. An associated
upper low will swing a large area of vort energy into the base of
the trof which will create increasing ulvl difl flow over the FA
with pockets of energy traversing the flow. At the llvls...there are
sigfnt disagreements wrt the synoptic pattern. The NAM is developing
a moist/stable insitu wedge, which lasts throughout the period. This
is not supported by the other op models nor the ens guidance. Thus
the NAM will be treated as an outlier and will count on a good
amount of destabilization during the afternoon.
If they are right this threat will cover a larger area in GA, NC, and SC for a much longer time. A BIG concern will also of course be where the boundary would set up if the NAM turns out to be right. Areas near it would have an even better chance of getting a tornado.
NAM is running.
Obviously the threat for more widespread issues is in the area all of you have been talking about but up this way my concern is it happens at night and this from Rah NWS
Despite poor diurnal timing, 12Z guidance suggests significant
nocturnal destabilization will occur Wed night (in the wake of the
initial round of convection Wed aft/eve) as seasonably rich low-
level moisture advects poleward underneath steep mid-level lapse
rates along/ahead of a cold front progressing eastward into the
Carolinas in the presence of pronounced height falls /DPVA/ and
increasingly diffluent flow aloft as the approaching upper level
trough acquires a negative tilt as shortwave energy rounding the
base in the Deep South ejects NE into the Carolinas. 0-6km shear
will be supportive of discrete supercells for a few hours in advance
of the cold front early Thu morning. Tornado potential may be
greatest during this time frame.
Despite poor diurnal timing, 12Z guidance suggests significant
nocturnal destabilization will occur Wed night (in the wake of the
initial round of convection Wed aft/eve) as seasonably rich low-
level moisture advects poleward underneath steep mid-level lapse
rates along/ahead of a cold front progressing eastward into the
Carolinas in the presence of pronounced height falls /DPVA/ and
increasingly diffluent flow aloft as the approaching upper level
trough acquires a negative tilt as shortwave energy rounding the
base in the Deep South ejects NE into the Carolinas. 0-6km shear
will be supportive of discrete supercells for a few hours in advance
of the cold front early Thu morning. Tornado potential may be
greatest during this time frame.
GTWXAlum
Member
ForsythSnow
Moderator
One thing that jumps out is the Omegas, which if I remember, represent something involving the strength of a storm or development strength of a storm. Looking at the temps and dew points, they seem unstable, so that could explain the Omegas being high.This is the sounding across Southeast TN between the morning and afternoon convection...I'm not good at these. Any help would be appreciated, thx guys.
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GTWXAlum
Member
FFC:
...Significant Severe Weather Outbreak Expected on Wednesday...
While today's warm and sunny weather provided a brief respite from
the stormy weather, this break will be coming to an abrupt end
on Wednesday. A strong storm system currently over the Plains will
bring widespread thunderstorms to the CWA on Wednesday, many of
which will become severe.
By early Wednesday morning a warm front will be rapidly moving
northward into the area ushering in Gulf moisture. The first
thunderstorms of the day are expected to form along this northward-
advancing warm front during the morning hours. Any thunderstorms
that form during this time frame may become severe. Large hail will
be possible with any elevated activity north of the front while
damaging winds and tornadoes would be possible with thunderstorms
forming along and just south of the warm front in the warm sector.
As we approach midday into the early afternoon, additional
widespread thunderstorm development is expected across the CWA with
a strong upper jet and associated divergence aloft as well as ample
instability in place across the warm sector. Forecast
SBCAPE values in the 2000-3000 J/kg range are anticipated, which
if realized will provide plenty of fuel for these rapidly developing
thunderstorms. Impressive shear (for example, >50 knots of 0-6km
bulk shear) will also be in place. All of this is to say that an
appreciable severe thunderstorm outbreak is expected with tornadoes,
damaging winds, and large hail all increasingly likely. The
possibility for strong/long-track tornadoes will exist with any
discrete supercells that form.
With such a moist environment in place, heavy rainfall can also be
expected in these thunderstorms. At this point, expected rainfall
totals are not high enough to warrant widespread flooding
concerns, but localized issues will be possible. See the hydrology
section below for further details.
The threat for severe thunderstorms will continue ahead of the
approaching cold front through the evening. As the cold front
finally begins to clear parts of the area mid-to-late evening, the
severe threat will end from west to east.
...Significant Severe Weather Outbreak Expected on Wednesday...
While today's warm and sunny weather provided a brief respite from
the stormy weather, this break will be coming to an abrupt end
on Wednesday. A strong storm system currently over the Plains will
bring widespread thunderstorms to the CWA on Wednesday, many of
which will become severe.
By early Wednesday morning a warm front will be rapidly moving
northward into the area ushering in Gulf moisture. The first
thunderstorms of the day are expected to form along this northward-
advancing warm front during the morning hours. Any thunderstorms
that form during this time frame may become severe. Large hail will
be possible with any elevated activity north of the front while
damaging winds and tornadoes would be possible with thunderstorms
forming along and just south of the warm front in the warm sector.
As we approach midday into the early afternoon, additional
widespread thunderstorm development is expected across the CWA with
a strong upper jet and associated divergence aloft as well as ample
instability in place across the warm sector. Forecast
SBCAPE values in the 2000-3000 J/kg range are anticipated, which
if realized will provide plenty of fuel for these rapidly developing
thunderstorms. Impressive shear (for example, >50 knots of 0-6km
bulk shear) will also be in place. All of this is to say that an
appreciable severe thunderstorm outbreak is expected with tornadoes,
damaging winds, and large hail all increasingly likely. The
possibility for strong/long-track tornadoes will exist with any
discrete supercells that form.
With such a moist environment in place, heavy rainfall can also be
expected in these thunderstorms. At this point, expected rainfall
totals are not high enough to warrant widespread flooding
concerns, but localized issues will be possible. See the hydrology
section below for further details.
The threat for severe thunderstorms will continue ahead of the
approaching cold front through the evening. As the cold front
finally begins to clear parts of the area mid-to-late evening, the
severe threat will end from west to east.
Could Georgia get its first ever EF5 tornado tomorrow ? I guess we'll have to wait and see.
JHS
Member
I live in a county that shows the point of this post perfectly. We are only got heavy rain and winds up to around 40 mph yesterday here in Jonesville, but a man died when his mobile him was flipped multiple times from what was probably a tornado about 25 miles away on the other side of the county.
Claycochaser
Member
What a crazy read this has been. At any rate lots of good points. I really don't see much that could mitigate the risk of Sig severe and tornado activity tomorrow. There will most likely be serious hazards with both the the early warm frontal convection and the Afternoon dryline storms. However, I've seen a lot of talk about historic events and dates...which could be getting some of you a little over anxious. On one hand, the memories of an April 27 serve to increase awareness and alertness when setups like tomorrow occur. That is a good thing. What's not a good thing is getting to the point where you are scared. We don't make good decisions when we are scared...so everyone with that level of concern...take a breath.
JHS
Member
That's from GSP.
metfascination
Member
So hard to believe that this time tomorrow will probably be a stark contrast to this gorgeous day. And will be a hell for some.
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ForsythSnow
Moderator
Per what TWC showed a little bit ago, they showed a map with all EF 5s, and only a small amount were in Georgia, so I believe there have been some already, but most if not all were from Alabama to Georgia.
What will be harder to believe is the cold behind the system, with highs in the low 50s possible in North Georgia Thursday. Crazy difference from 80s today, 70s and severe weather tomorrow, to 50s Thursday for a day.
metfascination
Member
pcbjr
Member
Tallahasssee NWS is giving it good due; NWS Jax is downplaying ... I'd go with Tall any day - they are very good forecasters there ...
Tall - key excerpts:
Area Forecast Discussion
National Weather Service Tallahassee FL
319 PM EDT Tue Apr 4 2017
.NEAR TERM [Tonight Through Wednesday]...
***Key Points***
SPC Outlook: The Storm Prediction Center has all but the Valdosta
region, a small portion of the Florida Panhandle, and most of the
Florida Big Bend outlooked in a Moderate Risk for Wednesday. The
remainder of the Tri-state region is outlooked for either enhanced
or for a slight risk.
Current Timing: The latest model guidance suggests that most
thunderstorms will develop after daybreak with initial development
likely over our western zones by mid to late morning with the
main threat in the afternoon in the moderate risk area. Conditions
are expected to clear late Wednesday night.
Threats: Current parameters suggest that all modes of severe
weather will be possible. Some strong (EF2+), long tracked
tornadoes are not out of the question. Destructive wind gusts of
70 mph, large hail the size of golf balls or larger will also be
possible. Additionally, high surf is expected along the Florida
Gulf Coast, with life threatening rip currents.
***Forecast Discussion***
.....
On Wednesday we are looking at a very active day with the surface
and upper level low deepening as they translate across the Missouri
Valley and into the Midwest. The southward trailing cold front will
approach our westernmost zones toward evening. This will be a very
dynamic system with operational and hi-res models showing several
parameters working together to bring a significant organized
severe weather event for our entire CWA. Latest guidance indicates
Mean CAPE 2000-3000 J/KG, 50+ Kts of bulk shear, mid-level lapse
rates ~ 7.5 C and impressive updraft velocities. The ECAM is also
showing several long updraft helicity tracks, especially across SE
AL and our northern GA zones. Convection is expected to increase
in coverage after daybreak Wednesday, with the vigorous storm
initiation expected to the west and northwest of the CWA. These
storms will move eastward into the CWA during the mid to late
morning hours and continue into the evening across our easternmost
zones.
.SHORT TERM [Wednesday Night Through Thursday Night]...
A residual severe weather threat may continue into effect
Wednesday night. Thunderstorms with the potential for large hail
and damaging winds cannot be ruled out. .....
Tall - key excerpts:
Area Forecast Discussion
National Weather Service Tallahassee FL
319 PM EDT Tue Apr 4 2017
.NEAR TERM [Tonight Through Wednesday]...
***Key Points***
SPC Outlook: The Storm Prediction Center has all but the Valdosta
region, a small portion of the Florida Panhandle, and most of the
Florida Big Bend outlooked in a Moderate Risk for Wednesday. The
remainder of the Tri-state region is outlooked for either enhanced
or for a slight risk.
Current Timing: The latest model guidance suggests that most
thunderstorms will develop after daybreak with initial development
likely over our western zones by mid to late morning with the
main threat in the afternoon in the moderate risk area. Conditions
are expected to clear late Wednesday night.
Threats: Current parameters suggest that all modes of severe
weather will be possible. Some strong (EF2+), long tracked
tornadoes are not out of the question. Destructive wind gusts of
70 mph, large hail the size of golf balls or larger will also be
possible. Additionally, high surf is expected along the Florida
Gulf Coast, with life threatening rip currents.
***Forecast Discussion***
.....
On Wednesday we are looking at a very active day with the surface
and upper level low deepening as they translate across the Missouri
Valley and into the Midwest. The southward trailing cold front will
approach our westernmost zones toward evening. This will be a very
dynamic system with operational and hi-res models showing several
parameters working together to bring a significant organized
severe weather event for our entire CWA. Latest guidance indicates
Mean CAPE 2000-3000 J/KG, 50+ Kts of bulk shear, mid-level lapse
rates ~ 7.5 C and impressive updraft velocities. The ECAM is also
showing several long updraft helicity tracks, especially across SE
AL and our northern GA zones. Convection is expected to increase
in coverage after daybreak Wednesday, with the vigorous storm
initiation expected to the west and northwest of the CWA. These
storms will move eastward into the CWA during the mid to late
morning hours and continue into the evening across our easternmost
zones.
.SHORT TERM [Wednesday Night Through Thursday Night]...
A residual severe weather threat may continue into effect
Wednesday night. Thunderstorms with the potential for large hail
and damaging winds cannot be ruled out. .....
NorthGaWinter4
Member
Storm I love bad storms, but it's scary when you have family memebers who live in a triple wide and a dad that will be in Atlanta traffic all day tomorrow...
ForsythSnow
Moderator
18Z NAM: Morning threat weaker, then scattered storms all afternoon, supercell line stronger than previous runs, and doesn't die out. It continues even into Eastern Georgia to the border of SC.
Storm5
Member
Damn the 3k 18z NAM develops cells on the Mississippi Alabama boarder and strengthens them as they move east
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Now this would be a problem for the Western half of the state. I'm pretty anxious to see the HRRR runs tonight. Also interesting that the low bombs out at 992.Damn the 3k 18z NAM develops cells on the Mississippi Alabama boarder and strengthens them as they move east
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NorthGaWinter4
Member
OMGDamn the 3k 18z NAM develops cells on the Mississippi Alabama boarder and strengthens them as they move east
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Storm5
Member
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pcbjr
Member
About the best free money you could ever spend (since registration and the benefits are free)!
Of course - donations do help make this place the best in the business ... just sayin'
pcbjr
Member
Isn't it true about pictures being worth a 1000 words ...
GTWXAlum
Member
^^ If that look verifies, Atlanta could be in major trouble with the potential for locally enhanced helicity right in the heart of the metro
pcbjr
Member
Not to downplay anything (and hopefully just a bit of levity before all Hades possibly breaks loose) - but it's been helicity every single time I've been downtown Hot'lanta ... LOL
skywatcher
Member
The best thing anyone can do at this point is to prepare. From Bill Murray at AlabamaWX Weather Blog:
"BE READY
Be sure to have your smartphone charged and fresh batteries in your flash lights, radios, and your NOAA Weather Radio. Know where your safe place is in your home, and be sure everyone know where it is. Already have helmets and hard sole shoes in there for everyone, and have a portable airhorn in case you need help."
I would also add, fill up your vehicle with gas, have bottled water and non-perishable food on hand, have a plan to contact your family members if the power goes out. Have cash on hand - credit/debit card scanners do not work during a power outage.
"BE READY
Be sure to have your smartphone charged and fresh batteries in your flash lights, radios, and your NOAA Weather Radio. Know where your safe place is in your home, and be sure everyone know where it is. Already have helmets and hard sole shoes in there for everyone, and have a portable airhorn in case you need help."
I would also add, fill up your vehicle with gas, have bottled water and non-perishable food on hand, have a plan to contact your family members if the power goes out. Have cash on hand - credit/debit card scanners do not work during a power outage.
Last edited:
RollTide18
Member
Just asking, is there any chance that the 3km NAM could be overdoing things? I mean either way, it looks nasty but just wondering.
Concerned. 18Z NAM moves a supercell right over Cleveland TN Bradley county
Any guesses as to the hours of most danger tomorrow in Atlanta (in the city, itself) based on model consensus? Is there actually a good consensus on the timing there? I'd like to pass this info to some relatives who are there. Thanks in advance.
So if i'm looking at the map correctly, it looks like the tornado parameters drop off significantly just north of Atlanta, so basically this will be an I-20 and south event ?
Storm5
Member
Yes ,it hasn't been very good lately