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Severe 3/21-3/24 Severe Weather
- Thread starter SD
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Z
Zander98al
Guest
Not sure at the tornado potential within the line, now if it's broken up sure, seems like you'll have a lot of straightline winds with embedded possibly strong spin ups. Your best tornado potential will be in that southern portion of Mississippi. Now you may have cells form right in front of the line and go tornadic but will quickly be swallowed up by the line
Z
Zander98al
Guest
I actually think your moderate will probably shift a bit more east tommorow in the new outlook. After looking at things closer the western half of Alabama looks best to me honestly.
Your going to have a decent bit of sun breaks near the state line, raising those surface to 3km lapse rates and adding higher instability, give the HRRR a few more model runs of the long range and it will catch up to higher imstability in the western half. Your focal point will probably be near that state line for discreet convection.
Your going to have a decent bit of sun breaks near the state line, raising those surface to 3km lapse rates and adding higher instability, give the HRRR a few more model runs of the long range and it will catch up to higher imstability in the western half. Your focal point will probably be near that state line for discreet convection.
PRETTY RIPE ENVIROMENT I THINK
AND ON TOP OF THE THREAT OF TORNADOS, HIGH WINDS AND SUCH WE ALSO HAVE A FLOOD TREAT
NEW DAY 2 IS OUT.. SLGT RISK AREA EXTENDED, EHN AND MDT AREA STAYS THE SAME
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
0102 AM CDT Mon Mar 21 2022
Valid 221200Z - 231200Z
...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS FROM PORTIONS OF
SOUTHERN AND EASTERN LOUISIANA INTO SOUTHERN AND CENTRAL
MISSISSIPPI...
...SUMMARY...
A regional severe weather outbreak -- including potential for
significant/damaging tornadoes -- remains evident over the Lower
Mississippi Valley/central Gulf Coast region Tuesday.
...Synopsis...
An expansive upper trough -- extending from arctic north-central
Canada to Mexico -- will stretch across central U.S./Plains states
at the start of the period. A surrounding/highly amplified belt of
cyclonic flow will cover much of the country, though flanking/stout
ridging will reside over both the western and eastern states through
the period. This trough will make slow eastward progress, though a
digging lobe of short-wave energy is forecast to shift out of New
Mexico across Far West Texas, and into northern Mexico during the
second half of the period.
At the surface, an occluding low should reside over eastern Kansas
at the start of the period, with a cold front extending southward
across East Texas. A synoptic warm front is expected to reside over
the Tennessee Valley/Mid South region through the day, though the
effective warm front -- making the northern fringe of the higher
theta-e Gulf boundary layer, will remain farther south. Northward
advance of this front will likely be influenced by convection to the
cooler side of this boundary.
By latter stages of the period, the low should reside over the
Illinois vicinity, with the cold front extending from the Tennessee
Valley to western portions of the Florida Panhandle.
...Far eastern Texas to Alabama...
Indications are that an outbreak of severe storms remains likely
Tuesday, centered across the lower Mississippi Valley region and
vicinity.
Thunderstorms -- and all-hazards severe risk -- will be ongoing at
the start of the period from East Texas across the Arklatex region.
Steady eastward progression of this band of pre-frontal convection
will occur, as persistent warm sector southerlies advect Gulf
moisture northward. Given very strong south-southwesterly flow
aloft atop the low-level southerlies, and aided by an amply unstable
airmass, strongly rotating storms are expected through the morning,
spreading out of east Texas and into Louisiana. Tornadoes --
including potential for significant events -- remain a likelihood,
along with damaging winds and hail.
In addition to the pre-frontal band of storms that will spread
eastward with time across the ENH and eventually MDT risk areas,
isolated cellular development will be possible in a zone of strong
warm advection ahead of the primary convective band. Any such cells
would quickly acquire updraft rotation, and would pose potential for
significant/damaging tornadoes. As such, some areas may experience
more than one round of potentially significant weather.
The bounds of the northern fringe of the risk area remain difficult
to discern, as very strong shear will exist well north, but with
ongoing/elevated convection likely to limit northward advance of
more favorable low-level air. Still, severe storm risk currently
appears to extend at least as far north as northern
Mississippi/northern Alabama.
Severe/tornado risk will continue through the evening/overnight as
the cold front -- and associated pre-frontal convection -- advances.
At this time, it appears risk may extend as far east as eastern
Alabama and western parts of the Florida Panhandle late in the
period.
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
0102 AM CDT Mon Mar 21 2022
Valid 221200Z - 231200Z
...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS FROM PORTIONS OF
SOUTHERN AND EASTERN LOUISIANA INTO SOUTHERN AND CENTRAL
MISSISSIPPI...
...SUMMARY...
A regional severe weather outbreak -- including potential for
significant/damaging tornadoes -- remains evident over the Lower
Mississippi Valley/central Gulf Coast region Tuesday.
...Synopsis...
An expansive upper trough -- extending from arctic north-central
Canada to Mexico -- will stretch across central U.S./Plains states
at the start of the period. A surrounding/highly amplified belt of
cyclonic flow will cover much of the country, though flanking/stout
ridging will reside over both the western and eastern states through
the period. This trough will make slow eastward progress, though a
digging lobe of short-wave energy is forecast to shift out of New
Mexico across Far West Texas, and into northern Mexico during the
second half of the period.
At the surface, an occluding low should reside over eastern Kansas
at the start of the period, with a cold front extending southward
across East Texas. A synoptic warm front is expected to reside over
the Tennessee Valley/Mid South region through the day, though the
effective warm front -- making the northern fringe of the higher
theta-e Gulf boundary layer, will remain farther south. Northward
advance of this front will likely be influenced by convection to the
cooler side of this boundary.
By latter stages of the period, the low should reside over the
Illinois vicinity, with the cold front extending from the Tennessee
Valley to western portions of the Florida Panhandle.
...Far eastern Texas to Alabama...
Indications are that an outbreak of severe storms remains likely
Tuesday, centered across the lower Mississippi Valley region and
vicinity.
Thunderstorms -- and all-hazards severe risk -- will be ongoing at
the start of the period from East Texas across the Arklatex region.
Steady eastward progression of this band of pre-frontal convection
will occur, as persistent warm sector southerlies advect Gulf
moisture northward. Given very strong south-southwesterly flow
aloft atop the low-level southerlies, and aided by an amply unstable
airmass, strongly rotating storms are expected through the morning,
spreading out of east Texas and into Louisiana. Tornadoes --
including potential for significant events -- remain a likelihood,
along with damaging winds and hail.
In addition to the pre-frontal band of storms that will spread
eastward with time across the ENH and eventually MDT risk areas,
isolated cellular development will be possible in a zone of strong
warm advection ahead of the primary convective band. Any such cells
would quickly acquire updraft rotation, and would pose potential for
significant/damaging tornadoes. As such, some areas may experience
more than one round of potentially significant weather.
The bounds of the northern fringe of the risk area remain difficult
to discern, as very strong shear will exist well north, but with
ongoing/elevated convection likely to limit northward advance of
more favorable low-level air. Still, severe storm risk currently
appears to extend at least as far north as northern
Mississippi/northern Alabama.
Severe/tornado risk will continue through the evening/overnight as
the cold front -- and associated pre-frontal convection -- advances.
At this time, it appears risk may extend as far east as eastern
Alabama and western parts of the Florida Panhandle late in the
period.
BMX EXTENED THE SLGT RISK AREA, KEPT EHN THE SAME
Area Forecast Discussion
National Weather Service Birmingham AL
359 AM CDT Mon Mar 21 2022
.SHORT TERM...
/Updated at 0356 AM CDT Mon Mar 21 2022/
Through Tuesday Morning.
High pressure over the area tonight will begin to shift east today.
However until it slides east of the area, we will remain in a
very dry airmass. Temperatures will generally be 70s. Tonight the
high should be to our east and southerly flow will increase moisture
in the area. Look for a much more mild night with lows in the upper
40s and low 50s. Should remain rain free for most of the night with
only increasing clouds. As we work into Tuesday morning look for
cloudy skies and some rain approaching the area, while the stronger
storms will be to our west. We could begin to see an increase in
rain showers after 10 AM in the south and west, so have included
some low end chances through 1 PM.
Tuesday afternoon into early Wednesday.
We continue to expect a multi weather hazard day across Central
Alabama on Tuesday, mainly Tuesday afternoon into Tuesday night.
This will include strong to severe thunderstorms capable of
producing tornadoes, damaging wind gusts, and large hail. Convection
will also produce periods of locally heavy rainfall, and we
currently forecast 2-3" with locally higher amounts along and north
of I-20 and west of I-65, including the BHM metro area. This could
lead to flash flooding given favorable antecedent conditions (high
soil moisture), as well as in poor drainage/urban areas. A tight
pressure gradient and strong low-level jet will also promote non-
thunderstorm wind gusts of 35-40 mph at times.
Latest forecast thinking has stayed in the same ball park, overall.
The signal for severe weather remains, and coincides with a broad
region of synoptic forcing approaching the Deep South on Tuesday.
This primarily stems from the an amplified upper-level trough, as
well as additional support from a shortwave ejection across the
lower Mississippi Valley late Tuesday afternoon into Tuesday
evening. Heights steadily fall through this time, and the
approaching 60+ kt southerly LLJ will foster a corridor of
increasing BL moisture/theta-e from the Gulf. Dewpoints are forecast
to climb into the low to mid 60s as a result, and these values
should allow for MLCAPE of 500-1,000 J/kg assuming mid-level lapse
rates remain in a range of 6-7 C/km. An abundance of wind shear will
also be present, and favorable values reside in both deep-layer and
low-level parameters to support supercells; both line-embedded in the
approaching MCS, or more discrete cells that could develop ahead of
the MCS. Some HREF members (HRRR, NAM3, NSSL WRF) suggest this could
occur by mid afternoon in our southwest counties due to little/no
CINH and abundant forcing aloft. Their updraft strength will depend
on CAPE profiles. Other hi-res guidance favors a QLCS scenario, and
the overall MCS could become quite messy as it impacts Central
Alabama.
Threat areas remain the same relatively speaking, and it`s the
quality of BL moisture and surface-based instability that have
hinged the forecast so far. Global models have struggled to bring
meaningful CAPE northward, and the ECMWF still favors a coastal
convection scenario owing to split jet/upper-level divergence. This
would mute CAPE for interior portions of Alabama, inhibiting severe
potential. On the other hand, recent hi-res guidance has suggested a
more robust warm sector, and a more northward extent, for areas west
generally closer to the Mississippi state line. This was the main
reason for expanding the "Slight" area on tonight`s update. If more
meaningful dewpoints/theta-e values can ascend to the north, severe
potential would certainly increase given the other supporting
parameters in place. All things considered, we could see severe
weather potential beginning as early as ~2 PM in the west (GFS,
HRRR, HRW FV3 timing), or as late as ~5 PM (NSSL WRF, NAM, GDPS
timing). I adjusted our messaging/timing accordingly. Depending on
convective evolution, which is nearly impossible to accurately
predict right now, we could have storms lingering in our
south/southeast counties toward ~6 AM Wednesday. The "Enhanced" area
was left relatively unchanged as this remains to be the best overall
overlap of thermodynamics/kinematics supportive of severe weather.
In near future forecast updates, we`ll likely have need for a Flood
Watch, as well as a Wind Advisory.
Area Forecast Discussion
National Weather Service Birmingham AL
359 AM CDT Mon Mar 21 2022
.SHORT TERM...
/Updated at 0356 AM CDT Mon Mar 21 2022/
Through Tuesday Morning.
High pressure over the area tonight will begin to shift east today.
However until it slides east of the area, we will remain in a
very dry airmass. Temperatures will generally be 70s. Tonight the
high should be to our east and southerly flow will increase moisture
in the area. Look for a much more mild night with lows in the upper
40s and low 50s. Should remain rain free for most of the night with
only increasing clouds. As we work into Tuesday morning look for
cloudy skies and some rain approaching the area, while the stronger
storms will be to our west. We could begin to see an increase in
rain showers after 10 AM in the south and west, so have included
some low end chances through 1 PM.
Tuesday afternoon into early Wednesday.
We continue to expect a multi weather hazard day across Central
Alabama on Tuesday, mainly Tuesday afternoon into Tuesday night.
This will include strong to severe thunderstorms capable of
producing tornadoes, damaging wind gusts, and large hail. Convection
will also produce periods of locally heavy rainfall, and we
currently forecast 2-3" with locally higher amounts along and north
of I-20 and west of I-65, including the BHM metro area. This could
lead to flash flooding given favorable antecedent conditions (high
soil moisture), as well as in poor drainage/urban areas. A tight
pressure gradient and strong low-level jet will also promote non-
thunderstorm wind gusts of 35-40 mph at times.
Latest forecast thinking has stayed in the same ball park, overall.
The signal for severe weather remains, and coincides with a broad
region of synoptic forcing approaching the Deep South on Tuesday.
This primarily stems from the an amplified upper-level trough, as
well as additional support from a shortwave ejection across the
lower Mississippi Valley late Tuesday afternoon into Tuesday
evening. Heights steadily fall through this time, and the
approaching 60+ kt southerly LLJ will foster a corridor of
increasing BL moisture/theta-e from the Gulf. Dewpoints are forecast
to climb into the low to mid 60s as a result, and these values
should allow for MLCAPE of 500-1,000 J/kg assuming mid-level lapse
rates remain in a range of 6-7 C/km. An abundance of wind shear will
also be present, and favorable values reside in both deep-layer and
low-level parameters to support supercells; both line-embedded in the
approaching MCS, or more discrete cells that could develop ahead of
the MCS. Some HREF members (HRRR, NAM3, NSSL WRF) suggest this could
occur by mid afternoon in our southwest counties due to little/no
CINH and abundant forcing aloft. Their updraft strength will depend
on CAPE profiles. Other hi-res guidance favors a QLCS scenario, and
the overall MCS could become quite messy as it impacts Central
Alabama.
Threat areas remain the same relatively speaking, and it`s the
quality of BL moisture and surface-based instability that have
hinged the forecast so far. Global models have struggled to bring
meaningful CAPE northward, and the ECMWF still favors a coastal
convection scenario owing to split jet/upper-level divergence. This
would mute CAPE for interior portions of Alabama, inhibiting severe
potential. On the other hand, recent hi-res guidance has suggested a
more robust warm sector, and a more northward extent, for areas west
generally closer to the Mississippi state line. This was the main
reason for expanding the "Slight" area on tonight`s update. If more
meaningful dewpoints/theta-e values can ascend to the north, severe
potential would certainly increase given the other supporting
parameters in place. All things considered, we could see severe
weather potential beginning as early as ~2 PM in the west (GFS,
HRRR, HRW FV3 timing), or as late as ~5 PM (NSSL WRF, NAM, GDPS
timing). I adjusted our messaging/timing accordingly. Depending on
convective evolution, which is nearly impossible to accurately
predict right now, we could have storms lingering in our
south/southeast counties toward ~6 AM Wednesday. The "Enhanced" area
was left relatively unchanged as this remains to be the best overall
overlap of thermodynamics/kinematics supportive of severe weather.
In near future forecast updates, we`ll likely have need for a Flood
Watch, as well as a Wind Advisory.
Last edited:
Z
Zander98al
Guest
If your going to start seeing any big shifts in the threat area or possible mode it should start soon.
Z
Zander98al
Guest
Right on cue 12z HRRR... I'll wait till it's finished to comment.
The SPC has now placed all of DFW under the highest risk area for severe weather today.
Could be rough for all of the Texas Triangle big cities.
Could be rough for all of the Texas Triangle big cities.
Solid environment near those storms on the AL/MS border again, but 1km and 6km shear vectors are almost parallel and there’s poor Storms relative winds between 3km and 6km on Hodographs in the risk area which increase the chances for cool pool interaction and is bad for discrete convection given it causes poor ventilation, honestly favorable soundings for training convection and flooding, that’s the most underrated risk tommorow 
I’d bet on some grunge HP supercells/embedded in the QLCS tomorrow with the sort of kinematics we are working with.
HSVweather
Member
Z
Zander98al
Guest
Your best bet for isolated tornadic supercells will probably be right around the state line, not the best environment but still good enough to rotate and cause tornadoes, south Mississippi area is still by far the better area though
Kidney bean threat level 7.5
DadOfJax
Member
Yep....Moderate risk for flooding....that's a good bet with this system.
The Day 1 Outlook also mentions the possibility of a moderate risk upgrade for East Central Texas.
Z
Zander98al
Guest
Once that qcls crosses the Mississippi river on the 12z HRRR, Everything goes to broken line and semi discrete.
Z
Zander98al
Guest
HSVweather
Member
12Z NAM and 12Z HRRR STP for tomorrow into tomorrow night. HRRR higher and makes it further east into Alabama. NAM hits a wall before reaching AL due to a lack of SBCAPE.
