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Severe 3/27-4/2 2025 Severe

The 12z GFS just screams one of the setups that give us problems in the south and big headaches for the NWS offices. One of those setups where if you break the cap at the right time, you have a extremely dangerous setup. If the cap breaks late, winds veer and big Hail is the main threat.

Looks like a supercellfest.
 
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Brent said:
Largest day 7 ever issued by the SPC for Sunday
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Just out of curiosity, how does one find out stats like that? I see people posting stuff like this all the time.

Largest area ever covered by the SPC in a D7 outlook.

The 9 largest tornado warnings ever issued were larger than the slight risk area today.

And so forth.
 
Rain Cold said:
Just out of curiosity, how does one find out stats like that? I see people posting stuff like this all the time.

Largest area ever covered by the SPC in a D7 outlook.

The 9 largest tornado warnings ever issued were larger than the slight risk area today.

And so forth.
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The Iowa Environmental Mesonet website is a place where you can get information like this. There are a lot of statistics on the site about SPC outlooks, watches, and warnings.

Here’s an example showing the largest day-7 SPC outlooks:

IMG_0689.jpeg
 
BufordWX said:
The Iowa Environmental Mesonet website is a place where you can get information like this. There are a lot of statistics on the site about SPC outlooks, watches, and warnings.

Here’s an example showing the largest day-7 SPC outlooks:

View attachment 172024
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Just to add to this but you can find NWS products from the 1990s on there 🤣

I've even found stuff from the blizzard of 93 and Palm Sunday 1994 when the Alabama church got destroyed by a tornado with no warning received(spoiler they just didn't have a way to get warnings)
 
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BufordWX said:
The Iowa Environmental Mesonet website is a place where you can get information like this. There are a lot of statistics on the site about SPC outlooks, watches, and warnings.

Here’s an example showing the largest day-7 SPC outlooks:

View attachment 172024
Click to expand...
Awesome! Thank you. I really appreciate it!

Just trying it out, the severe thunderstorm warnings from this morning was the 4,324th largest warning ever issued. 😅
 
Brent said:
Just to add to this but you can find NWS products from the 1990s on there 🤣

I've even found stuff from the blizzard of 93 and Palm Sunday 1994 when the Alabama church got destroyed by a tornado with no warning received(spoiler they just didn't have a way to get warnings)
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They actually go back to the 1980's, but a lot of that data is missing. I especially like the state forecast discussions and AFDs. Warning and special weather statements too.
 
BufordWX said:
Latest SPC extended outlook has removed the risk area for Saturday (3/29) due to a lack of storm development. Meanwhile, Sunday (3/30) remains largely the same, and there was also the introduction of a 15% risk area for the Carolinas and Georgia for Monday (3/31).

Sunday:
View attachment 172027

Monday:
View attachment 172028
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Already
Concerned bout super cells mainly …. Interesting.
 
The wind fields and 500mb look over TN on last night's euro is the best supercell printing look I've seen in quite a while. The one fly may be that surface winds are modeled to veer which I am not convinced happens but per model it could help reduce the tornado risk some. That said the model isn't as scary as yesterday's 12z south of say Huntsville.
 
Kinda feels like this is a set up you would see more in May rather than March. Pretty impressive instability values showing for Sunday on the GFS, but wind fields are a bit more in question with this being a more low-amplitude wave. I would imagine that there may be some decent hailers with storms that develop. Also, there will probably be a region with a higher tornado threat as well, but it’s too early to say exactly where. 1742963366138.png
 
NWS BMX IS SOMEWHAT CONSERNED WITH THE NEWEST DATA, GIVEN THIS MAY, THE WORDING IS NOT SOUNDING TO GOOD WITH NOW


FROM NWS BIRMINGHAM

.LONG TERM...
(Thursday night through Tuesday)
Issued at 347 AM CDT WED MAR 26 2025

Quiet weather will continue through Friday night, and then more
ominous a low-amplitude jet stream will take shape over the CONUS
during the weekend. A small lead shortwave will eject across
Alabama on Saturday, generating showers and embedded
thunderstorms within deep southerly flow from the Gulf.

The shortwave on Saturday will act as a primer wave for a much
larger, broad 500 mb trough that will move toward the Mississippi
Valley on Sunday. Moderate to relatively high amounts of CAPE
across a large area will be present across the warm sector Sunday
afternoon into Sunday night. Model trends are more concerning
than 24 hours ago with the evolution of this trough and the
proximity of the upper-level support to Central Alabama. The
broad and subtle nature of the lift with this system strongly
suggests the storm mode will be in the form of supercells with
excellent surface/850 mb/500 mb crossovers. At face value the
ECMWF indicates an early morning to late morning tornado outbreak
from our western to our eastern border. At the 120 hour range, it
is too early to ring the alarm bells since subtle changes in the
evolution of the upper-level wave will have significant
implications for the threat level across Alabama.


LATEST SPC FOR DAY BELOW:
Day 5/Sunday, more substantial cyclogenesis is expected, though
differences exist between the models in terms of timing/location of
the developing low -- and associated cold front. Nonetheless,
substantial warm-sector destabilization is forecast to occur from
Missouri/Arkansas/eastern Texas eastward across the Mississippi
Valley during the day, and extending eastward across the
Midwest/Ohio and Tennessee Valleys. This will support scattered
thunderstorm development, within an increasingly sheared
environment. By early afternoon, severe/supercell storms are
expected, accompanied by the risk for very large hail, damaging
winds, and a few tornadoes. Storms should spread southeast of the
Ohio and Mississippi Valleys overnight, accompanied by ongoing
severe risk.
 
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Day 4 outlook for Monday is crazy large. 15% risk area from Boston to the gulf coast. Looks like the main threat is for damaging winds.1743179726103.gif
 
Rain Cold said:
North end of the area is questionable, in terms of instability.
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Yeah, this treat will probably be from southern VA back to east AL. It looks like we may be getting this during peak heating too in the GSP area.

A cold front associated with a low pressure system tracking thru
the Great Lakes will cross the Ohio Valley Sunday, and is expected
to cross our area Monday. There looks to be some lull in shower
activity early Monday, with low clouds having some opportunity to
scatter out. Guidance is in decent agreement on the front crossing
the forecast area during peak heating, with sbCAPE of 500-1000
J/kg and 0-6 km shear of 40-50 kt. Unless the timing of the front
significantly changes, there looks to be a decent threat of strong
to severe storms. Temps will continue to be above normal Monday.

That much shear and CAPE probably means a threat for tornados along with wind and hail.
 
From the SPC's afternoon Day 3 update:

...Mid-South...
Ahead of the southeastward moving cold front, dewpoints are expected
to rise to the mid to potentially the upper 60s (the NAM being
typically more aggressive in this regard). Given the presence of an
elevated mixed layer, this region is expected to have little to no
thunderstorms expected during the morning/early afternoon. Surface
heating and increasing mid-level ascent should eventually erode the
cap and allow storms to develop by mid/late afternoon. There is some
indication that a pre-frontal trough/confluence zone may set up.
Should this occur, the potential for discrete storms would increase
along with the potential for a more concerning tornado risk.
Low-level wind fields will likely be somewhat weaker in these areas
given the southward displacement from the surface low. However,
forecast soundings suggest low-level hodograph curvature will be
more than sufficient, particularly beyond early evening. Even
without pre-frontal discrete development, the greater surface
heating expected in this region should allow for widespread severe
storms along the cold front with a threat for large hail, widespread
damaging winds, and QLCS tornadoes.
 
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