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March 18-19th Possible Severe Wx Outbreak

NAM 12km looks like nothing much for Charlotte-west (for the first line at least)
 
Nam is sooo different compared to the HRRR, NAM has another area of impressive SCP move into WNC/SC with storms firing along the foothills while the hrrr is just the line then done
 
Myfrotho704_ said:
Nam is sooo different compared to the HRRR, NAM has another area of impressive SCP move into WNC/SC with storms firing along the foothills while the hrrr is just the line then done
Click to expand...

What’s interesting is the Nam has been consistent on this second round. Meanwhile local meteorologist are not even mentioning anything after the first line. Really I’m not worried about the first line Im not expecting much from it. If there’s a round two that develops those storms would be concerning.


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Atl 64 with dew at 63 Gainesville 52/50 it's comin

That was a point and click reading can't find that one again I see 54 and 57 in atl maybe that 64 was under a station with a reading lamp inside ;)

Newnan coweta airport 62 so it's in the neighborhood
 
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WRAL has been hyping the hell out of tomorrow's threat since Monday.
 
Maybe models just aren’t picking up on the idea of small supercells tomorrow or handling things well... but this is not what I expect for a mod outbreak (in NC) as currently forecast. 19z tomorrow we have light rain moving in.

1616035344213.png

Echo tops are also quite shallow, just very little deep convection in NC.
1616035485270.png

It’s been my experience with severe weather threats that when models show some red flags like this, a potential bust is in the cards. I’m not saying people shouldn’t take this seriously, I get that parameters and soundings indicate the potential for an outbreak and models could be completely missing it here. But the signs point to clouds, stabilizing light precip during peak heating, and shallow convection. What I’m seeing on the 3km NAM and HRRR runs has consistently indicated this as well across NC in contrast to the widespread outbreak being forecast. Something to watch as things unfold tomorrow morning.
 
snowlover91 said:
Maybe models just aren’t picking up on the idea of small supercells tomorrow or handling things well... but this is not what I expect for a mod outbreak as currently forecast. 19z tomorrow we have light rain moving in.

View attachment 79516

Echo tops are also quite shallow, just very little deep convection in NC.
View attachment 79517

It’s been my experience with severe weather threats that when models show some red flags like this, a potential bust is in the cards. I’m not saying people shouldn’t take this seriously, I get that parameters and soundings indicate the potential for an outbreak and models could be completely missing it here. But the signs point to clouds, stabilizing light precip during peak heating, and shallow convection. What I’m seeing on the 3km NAM and HRRR runs has consistently indicated this as well in contrast to the widespread outbreak being forecast. Something to watch as things unfold tomorrow morning.
Click to expand...

Which is what happens 99% of the time with severe threats here the last decade. We get some clouds and showers before the main event and not enough clearing to really give the spark needed for a widespread event.
 
CAMs have good parameters but what look like showers/mini supercells after the main line
 
A portion of CAE's latest AFD regarding tomorrow's severe wx potential:

Area Forecast Discussion
National Weather Service Columbia SC
1045 PM EDT Wed Mar 17 2021

Synoptic Overview: A strong upper level low initially over the
Ozarks will shift eastward through the day into the Mid Atlantic
States. This will bring a cold front through the Southeast on
Thursday. During the morning, a loose line of showers and
thunderstorms will be west of the forecast area. Strong warm
advection ahead of the front will lead to moderate conditional
instability over the region and, in conjunction with a highly sheared
environment, support severe weather. This line of convection will
strengthen as it moves eastward through the day.

Timing Details: A line of strong thunderstorms will move into the
forecast area from the west on Thursday morning and continue
eastward through the FA, exiting during the evening. Latest CAM
guidance has been a little slower with the progression of the line.
HREF paintball diagrams suggest the line will enter the western FA
between late morning to mid-day, the central FA from mid-day to mid-
afternoon, then into the eastern FA from mid-afternoon to early
evening.

Severe Weather Potential: Confidence is high that severe weather
will occur. All of the environmental ingredients are supportive of
severe weather. The potential for significant severe weather is
increasing in confidence as well. A slower progression of the system
as seen in recent CAM runs would indicate more time for
destabilization before the line moves into the FA. This is reflected
in the SPC SREF as well, which shows increasing mean CAPE values
over the past several runs. Median surface based CAPE values from
the SREF are at or slightly higher then 1000 J/kg. The NAM mixed
layer CAPE values are marginally higher, around 1500 J/kg. These
values are higher than the previous day and support increasing
confidence in severe weather. Deep and low level wind shear will be
undoubtedly strong and support bowing segments within the convective
line in addition to embedded supercells and possibly discrete
supercells just ahead of the main line. This combination of moderate
instability and strong wind profiles will support widespread
damaging winds and a few tornadoes, potentially strong (EF2 or
greater), long-lived tornadoes. STP values from the 3km NAM add
confidence in tornadic potential showing a large area of values well
above 1, with a few pockets of 6-9. These pockets are largely in the
eastern half of the forecast area, closer to the I-95 corridor.
Although we can't rule out tornadoes for any point in the FA,
confidence is higher to the east. Although there is modest curvature
in the lowest 1km of forecast hodographs, at higher heights the
hodograph is closer to straight or even slightly backing. This may
allow for splitting updrafts and left-moving cells, which have been
known to produce large or even significant hail. The past 2 runs of
the SPC HREF ensemble have indicated swaths of highly negative
updraft helicities. This raises concerns for storms which may
produce large or even significant hail. In summary, on Thursday
there is potential for widespread damaging winds, large hail and a
few, but potentially significant tornadoes.
 
lj0109 said:
A portion of CAE's latest AFD regarding tomorrow's severe wx potential:

Area Forecast Discussion
National Weather Service Columbia SC
1045 PM EDT Wed Mar 17 2021

Synoptic Overview: A strong upper level low initially over the
Ozarks will shift eastward through the day into the Mid Atlantic
States. This will bring a cold front through the Southeast on
Thursday. During the morning, a loose line of showers and
thunderstorms will be west of the forecast area. Strong warm
advection ahead of the front will lead to moderate conditional
instability over the region and, in conjunction with a highly sheared
environment, support severe weather. This line of convection will
strengthen as it moves eastward through the day.

Timing Details: A line of strong thunderstorms will move into the
forecast area from the west on Thursday morning and continue
eastward through the FA, exiting during the evening. Latest CAM
guidance has been a little slower with the progression of the line.
HREF paintball diagrams suggest the line will enter the western FA
between late morning to mid-day, the central FA from mid-day to mid-
afternoon, then into the eastern FA from mid-afternoon to early
evening.

Severe Weather Potential: Confidence is high that severe weather
will occur. All of the environmental ingredients are supportive of
severe weather. The potential for significant severe weather is
increasing in confidence as well. A slower progression of the system
as seen in recent CAM runs would indicate more time for
destabilization before the line moves into the FA. This is reflected
in the SPC SREF as well, which shows increasing mean CAPE values
over the past several runs. Median surface based CAPE values from
the SREF are at or slightly higher then 1000 J/kg. The NAM mixed
layer CAPE values are marginally higher, around 1500 J/kg. These
values are higher than the previous day and support increasing
confidence in severe weather. Deep and low level wind shear will be
undoubtedly strong and support bowing segments within the convective
line in addition to embedded supercells and possibly discrete
supercells just ahead of the main line. This combination of moderate
instability and strong wind profiles will support widespread
damaging winds and a few tornadoes, potentially strong (EF2 or
greater), long-lived tornadoes. STP values from the 3km NAM add
confidence in tornadic potential showing a large area of values well
above 1, with a few pockets of 6-9. These pockets are largely in the
eastern half of the forecast area, closer to the I-95 corridor.
Although we can't rule out tornadoes for any point in the FA,
confidence is higher to the east. Although there is modest curvature
in the lowest 1km of forecast hodographs, at higher heights the
hodograph is closer to straight or even slightly backing. This may
allow for splitting updrafts and left-moving cells, which have been
known to produce large or even significant hail. The past 2 runs of
the SPC HREF ensemble have indicated swaths of highly negative
updraft helicities. This raises concerns for storms which may
produce large or even significant hail. In summary, on Thursday
there is potential for widespread damaging winds, large hail and a
few, but potentially significant tornadoes.
Click to expand...
This seems awfully aggressive to me given the outcome so far today as well as how fast the QLCS appears to be progressing
 
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