Severe WX Sunday March 3 Severe Threat

[Timhsv]

I ran some numbers and EHI's are very sufficient across an area from Cullman, AL. to south of Birmingham...., at 3.4- 4.7
I would like to see the 0-1KM a tad more SSE but its more than sufficient. Lapse Rates are so-so, but overall attm, a fairly solid threat.

 

[Taylor Campbell]

A look at the energy out west that will be responsible for this event.

 

[jmills]

21z SREF probabilities for STP >1 Sunday evening.

 

[Taylor Campbell]

The 00z NAM held serve to a significant event. It actually looks a bit stronger, and broader with the low-level winds.

 

[Richardjacks]

The 00z NAM held serve to a significant event. It actually looks a bit stronger, and broader with the low-level winds.

yes, IF the nam is correct. My gut tells me the warm front will not make it that far north..we shall see.

 

[Xenesthis]

yes, IF the nam is correct. My gut tells me the warm front will not make it that far north..we shall see.

I agree here. We will see....

 

[rolltide_130]

The 0z suites outside the NAM have not been impressive at all. Gonna need to see where the Euro falls, but my expectations are lowering..

 

[jmills]

Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0225 AM CST Fri Mar 01 2019

Valid 031200Z - 041200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS CENTERED OVER THE
CENTRAL GULF COAST REGION...

...SUMMARY...
Thunderstorms -- including potential for locally severe storms --
will likely exist across portions of the southeastern U.S. centered
over the central Gulf Coast region on Sunday.

...Synopsis...
Broad/relatively low-amplitude cyclonic flow will persist across the
U.S. Sunday, south of the main upper vortex progged to remain over
Ontario through the period. With respect to convective potential,
the primary upper feature of interest will remain the fast-moving
short-wave trough that will cross the southeastern quarter of the
U.S. before reaching the western Atlantic late in the period.

At the surface, a weak frontal wave will shift eastward across the
Gulf Coast states, and later the southern Appalachians and Carolinas
before shifting offshore. Meanwhile, a surge of polar air is
progged to spread south/southeast across much of the central and
eastern U.S. and northern Rockies through the period.

...Central Gulf Coast region and vicinity...
A relatively moist boundary layer is progged to reside ahead/south
of the frontal wave which will shift quickly across the region
Sunday, sufficient to support modest CAPE. While the low will
remain weak, and surface winds somewhat veered/southwesterly ahead
of the front south of the surface low, strong deep-layer flow will
accompany the upper system -- resulting in shear supporting
organized/rotating storms.

While primary risk will likely be wind, emanating from a few
small/bowing segments moving quickly east-northeastward, a couple of
tornadoes may also occur -- the most likely zone at this time
appearing to exist from southern/eastern Mississippi into central
Alabama, during the afternoon hours. As storms spread quickly
eastward into the evening, a decrease in intensity/severe risk is
expected, with risk likely to linger longest over portions of the
Florida Panhandle and southern Georgia.

..Goss.. 03/01/2019

 

[Taylor Campbell]

The 3KM NAM is looking like the 12KM. Updraft helicity streaks from MS into South Carolina with an increase intensity across east central AL, and west central GA. Simulated satellite looks menacing.

 

[champal3003]

GFS coming in line with Euro and Nam.......now has low just to north of Birmingham where last several runs had no low at all.

 

[Kory]

Euro gets the warm front north of I-20/59 but I’m not sure it’ll get much further north than that. Still looks rough from the corridor from Tuscaloosa to Birmingham to Anniston.

 

[Taylor Campbell]

This threat looks like easily an enhanced risk kind of day along, and south of the warm front.

The energy still remains over the Pacific ocean, and is forecast to move onshore late tomorrow morning.

 

[apocalyptic_pleasures]

S Alabama may go enhanced for a bit but the models seem to be decreasing the threat overall IMO. They are shoving this further and further South. In another 24 hrs this may become a coastal FL Panhandle threat only. In the graphic below the trend goes from Birmingham being in a SigTor risk to the back edge dropping to near Troy. Im really hoping we will be OK

 

[Daryl]

SPC not too impressed with tornado potential in their new outlook.

Day 2 Convective Outlook
With the upper system trailing well to the west of the surface
low/front, and weak low-level lapse rates anticipated, prospects for
cellular warm-sector storms appear limited at this time. These
factors -- combined with slightly veered/west-of-south orientation
to the surface winds expected in the warm sector -- should limit
overall tornado potential.

 

[MattW]

The 3km NAM is keeping the threat as far north as south metro Atlanta, but the HRRR is keeping everything south of Columbus, and is a bit faster.
EDIT: SREF is in the middle keeping the northern extent roughly centered between Columbus and Atlanta.

 

[Taylor Campbell]

I think there needs to be major changes to the SPC forecast. Not only does a greater than marginal risk look to extend all the way to the east coast, but there needs to be an enhanced risk to define the significance of the wind threat at the least. The probabilities here look to meet the 30% threshold. I also see reason to introduce 10% tornado probabilities and hatch it for the possibility of significant tornadoes. A developing surface low accompanied by a strengthening low-level jet over 50knts, and low amplitude 567-573 isobars dropping down over a pronounced warm sector historically provide significant severe weather events for this area. It's no surprise that all the high resolutions models show very high severe weather parameters for tomorrow.

 

[MattPetrulli]

SPC hatches a small corridor from about Columbus, GA to Enterprise, AL.


As the shortwave trough moves across the lower Mississippi Valley on
Sunday, a 75 to 90 kt mid-level jet will move across the Tennessee
Valley. The southeastern edge of this feature will enhance ascent
and aid strong deep-layer shear profiles. Due to this, a wind damage
threat should develop within the squall-line by midday. At
low-levels, a 40 to 60 kt jet is forecast to move eastward across
south-central Alabama during the afternoon. Discrete supercells that
form over the warm sector near and to the southwest of the low-level
jet max will have favorable shear profiles for tornadoes. The
number of tornadoes that develop will be dependent upon how many
discrete cells form out ahead of the cold front. If a cluster of
discrete cells can become scattered across the area with stronger
instability, then there could be a small cluster of tornadoes. The
greatest potential for tornadoes is currently forecast from just
north of Mobile east-northeastward to the east of Columbus, Georgia.
An enhanced has been added along this corridor where a potential
for strong tornadoes will exist. In addition to tornadoes, wind
damage and isolated large hail will also be possible with
supercells. A wind damage threat should also be concentrated along
the squall-line to the west. The squall-line should progress
eastward across the southern Gulf Coast States and into Georgia
during the late afternoon and early evening.

 

[CheeselandSkies]

LOL, Broyles is back to his old tricks, I see.

 

[TornadoFan]

Curious as to which model shows you where the warm sector is located.

 

[MattPetrulli]

Think the 12z HRRR drove SPC to hatch the area. Has multiple discrete cells developing across the warm sector with very favorable parameters