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5/9 - 5/11 severe wx

Bet the long range hrrr is gonna mix things out as usual in the afternoon
 
Sneaky setup for elevated thunderstorms sun night/mon morning bet there’s storms around, hrrr tries to hint at it but nam doesn’t show much reflectivity wise, but WAA/elevated cape argues against it C36D8D9F-0B51-4FC2-849B-B19AE7403695.pngDFD713AE-3B72-4FF7-86CA-CFA52AFADE59.pngC4D13094-BC43-420D-8845-677ADE20F28F.png03549922-D883-4BEC-A537-BC7CF8874150.png
 
I was watching this threat on models and was wondering if I should have posted anything lol. Decent QCLS In the tennessee valley from this. Pretty low cape for this time of the year
 
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ACUS01 KWNS 090537
SWODY1
SPC AC 090536

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1236 AM CDT Sun May 09 2021

Valid 091200Z - 101200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM PORTIONS
OF EASTERN TEXAS TO WESTERN TENNESSEE...

...SUMMARY...
Scattered severe storms are expected from parts of central/east
Texas into the lower Mississippi Valley and Mid-South. Large hail,
damaging wind gusts, and a couple of tornadoes all appear possible.

...Central Texas to Middle Tennessee...

Early this morning a mature MCS has evolved over northeast
KS/northwest MO in advance of a mid-level short-wave trough. This
complex of storms will likely begin to propagate southeast as LLJ
veers across the Ozark Plateau into southern IL by the start of the
period. Leading edge of this convection should approach southern MO
by daybreak, just ahead of the cold front which should advance to a
position from south-central MO-northwest AR-northern TX by 18z.

Latest short-range model guidance suggests weak mid-level height
falls will spread across the OH Valley during the day1 period as a
low amplitude trough ejects into IN by 18z, then into western PA by
early evening. In the wake of this feature, surface pressures will
rise over the middle of the country forcing a strong cold front to
surge south into the southern Plains and lower MS Valley during
peak-heating hours. This boundary will serve as the primary focus
for robust convection, along with outflow from aforementioned MCS as
it propagates into the Mid-South region.

Large-scale deep westerly flow will materialize across the
pre-frontal warm sector from north TX into TN as the primary LLJ
translates across KY into western PA ahead of the primary short
wave. As a result, boundary-layer heating and frontal convergence
will be the primary mechanisms for thunderstorm development.
Forecast soundings suggest supercells are likely ahead of the front
as surface-6km bulk shear will be on the order of 40kt where MLCAPE
values should exceed 2000 J/kg. Local hail algorithms suggest 2+
inch stones are possible with the strongest storms. Additionally,
while the more focused low-level shear/convergence will be well
northeast of this region, there is some potential for a few
tornadoes with these supercells. Overall, an elongated corridor of
scattered severe storms should ultimately evolve from portions of
central/northeast TX into western TN, primary along an axis of
stronger buoyancy.

..Darrow/Karstens.. 05/09/2021
—————————————————————————————————————————
CF040767-EBED-4D63-BB0E-D69F2B9886F9.png

South-Central Texas...
A nearly stalled front should extend across central TX on Monday,
with a dryline extending southward from this front into
north-central Mexico. Nearly zonal mid-level flow will persist over
the southern Plains, with nebulous large-scale forcing for ascent.
Even so, low-level convergence along the front and sharpening
dryline and modest east-southeasterly low-level flow should prove
sufficient in tandem with strong diurnal heating to foster isolated
convective development Monday afternoon/evening. The airmass
along/south of the front and east of the dryline should become
moderately to strongly unstable, with MLCAPE of 2000-3500+ J/kg
forecast. Although the stronger mid-level westerly flow is forecast
to remain mostly north of the front, winds should strengthen at
upper levels. Effective bulk shear of 40-50 kt will support
supercell structures with any storms that can form.

The presence of steep mid-level lapse rates and a long, generally
straight hodograph at mid/upper levels suggest large to perhaps very
large hail should be the main threat with any supercells. Isolated
severe/damaging wind gusts may also occur with both the initially
discrete storms, and any clusters that can develop
east-southeastward through the evening. There is still some
uncertainty with how much convection will ultimately form across the
warm sector in south-central TX given the lack of obvious forcing
aloft. But, the 12Z ECMWF and 00Z GFS both show a robust convective
precipitation signal, and some convection-allowing guidance also
develops multiple supercells across this region. Accordingly,
confidence in convective initiation occurring has increased enough
to include greater severe hail/wind probabilities across part of
south-central TX.

...Southern Virginia into the Carolinas...
A low-amplitude shortwave trough should move off the East Coast
early in the period. Other weak, convectively augmented mid-level
perturbations may move eastward across the Carolinas and vicinity
through the day. A trailing cold front extending across southern VA
into western NC should be the primary forcing mechanism that will
focus storm development Monday afternoon. Diurnal heating of a
fairly moist low-level airmass will probably support MLCAPE reaching
1000-1500 J/kg by peak afternoon heating. 30-40 kt of deep-layer
shear should foster a mix of supercells and clusters with initial
development, with a tendency for some upscale growth through the
afternoon and early evening given the linear forcing of the front.
Isolated large hail and damaging wind gusts both appear possible
with these storms as they move east-southeastward. They should
eventually move offshore and/or weaken by Monday evening.

...Lower Mississippi Valley into the Southeast...
Storms will probably be ongoing at the start of the period Monday
morning across some part of the lower MS Valley and Southeast, but
there is uncertainty with both the placement and intensity of this
convection. Most guidance suggests that the better isolated severe
storm threat should remain mostly to the south of these morning
storms. Somewhat farther north, a surface front will likely serve as
the northern limit for any appreciable severe potential. Given
nebulous large-scale ascent forecast in model guidance, it remains
unclear how much additional convection will develop Monday afternoon
along/south of the front. Any storms that do form could become
severe given a weakly to moderately unstable airmass and the
presence of 35-50 kt of westerly mid-level flow. Isolated large hail
and strong to damaging wind gusts should be the main threats. With
considerable uncertainty regarding overall storm coverage and the
effect of morning storms on the degree of destabilization Monday
afternoon, will maintain a broad Marginal Risk area.

...North-Central/East Texas to the ArkLaTex...
Isolated to scattered storms may form through the period from parts
of north-central/east TX to the ArkLaTex vicinity. Most of this
activity should occur to the north of a surface front. But, the
shallow nature of this front and the continued presence of steep
mid-level lapse rates should allow for a reservoir of potentially
moderate instability to remain across this region (MUCAPE around
1500-2500 J/kg). Large hail will likely be the main severe threat
with any storms that occur, as 40-50 kt of mid-level westerly flow
will foster similar values of effective bulk shear.

..Gleason.. 05/09/2021
 
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