ACUS01 KWNS 281934
SWODY1
SPC AC 281933

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0233 PM CDT Wed Apr 28 2021

Valid 282000Z - 291200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF TEXAS...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM TEXAS INTO
SOUTHERN IL/WESTERN KY AND ACROSS PARTS OF THE LOWER GREAT LAKES...

...SUMMARY...
Severe thunderstorms are possible across parts of the southern
Plains to southwest Texas through this evening. Other severe storms
may develop in parts of the lower Great Lakes region. In both
areas, the most intense thunderstorms may produce large hail and
wind damage. A tornado threat also may develop in the southern
Plains.

...20z Update...

Only minor adjustments have been made to outlook areas with the 20z
update. The main adjustments have been to trim the Marginal and
Slight risk areas across parts of northwest OK into northwest TX.
This is based on the current position of the cold front and where
persistent precipitation/cloud cover has limited destabilization.
The Slight risk also was expanded across parts of western KY where
an ongoing threat for damaging winds will continue the next several
hours. The Marginal risk has also be adjusted slightly southward
from MO into OH based on frontal position. Minor adjustments were
also made to the Enhanced risk/30% SIG Hail area in southwest TX
based on current position of developing convection. Otherwise,
overall forecast philosophy remains unchanged from the previous
outlook.

..Leitman.. 04/28/2021

.PREV DISCUSSION... /ISSUED 1131 AM CDT Wed Apr 28 2021/

...TX...
An upper low is over southeast AZ today, with strong southwesterly
midlevel winds extending across the southern Plains. At the surface
widespread moist and at least moderately unstable air is present
across much of central/east TX. Forecast soundings suggest the cap
is relatively weak today, which makes the timing/position of
convective initiation more uncertain. However, it appears the
primary forcing boundaries will be a remnant outflow boundary
extending from north of SJT to near MWL, and also the dryline west
of SJT. Both boundaries are likely to activate by mid/late
afternoon, with a risk of supercells capable of very large hail,
damaging winds. While low-level shear is not particularly strong,
presence of boundaries, ample CAPE, and discrete mode may promote a
risk of a few tornadoes across the ENH risk area through the
evening.

...West TX into OK...
Visible satellite imagery shows breaks in the clouds across much of
west TX into western OK. This overlaps the dryline from SJT
northward, where most 12z CAM solutions indicate the development of
scattered afternoon and evening thunderstorms. A few intense cells
are likely to form in this area, with a primary risk of large hail.

...Southern MO into Southern IL...
A cluster of organized/intense thunderstorms is affecting southern
MO this morning. This activity may persist through the day and
eventually track into southern IL/western KY. Shear is quite
strong, but instability is very limited in this corridor due to
cloud cover. Nevertheless, persistent convective organization may
allow for a continued risk of damaging wind gusts and occasional
tornado spin-ups through the day.

...OH/PA/NY...
A line of showers and thunderstorms is forecast to develop this
afternoon over Lake Erie and spread southeastward across the region.
Dewpoints in the mid 50s and relatively strong heating will result
in MLCAPE values around 1000 J/kg. Deep-layer vertical shear is
more than sufficient for a few rotating/bowing segments through the
afternoon posing a risk of hail. Low-level lapse rates will also be
steep in areas where heating is optimized, aiding in the development
of strong/damaging wind gusts.

$$

ACUS01 KWNS 311936
SWODY1
SPC AC 311934

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0134 PM CST Fri Dec 31 2021

Valid 312000Z - 011200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS MAINLY AFTER
MIDNIGHT FROM SOUTHEAST OK/NORTHEAST TX TO MIDDLE TN/SOUTHERN KY....

...SUMMARY...
Scattered severe thunderstorms remain possible, mainly from late
evening into the overnight across parts of the South-Central States
towards the Tennessee Valley.

...Northern AL/Northwest GA...
There will be a window of opportunity this afternoon for a period of
isolated strong/severe storms to affect northern AL and northwest
GA, within a weakly forced but favorably sheared environment. Refer
to MCD #2089 for further details on this scenario.

...Northeast TX/southeast OK to TN/KY...
The ongoing forecast remains on-track, with no changes made.
Thunderstorms will begin to develop after 10pm across the SLGT risk
area, with the primary severe threat mainly after midnight.
Sporadic hail and wind events may occur overnight in this corridor,
with the potential for a tornado or two if supercell structures can
develop.

..Hart.. 12/31/2021

.PREV DISCUSSION... /ISSUED 1020 AM CST Fri Dec 31 2021/

...Synopsis...
Within a large-scale trough over the western CONUS, one shortwave
trough just off the Baja CA coast will eject east-northeast to the
southern High Plains tonight, in advance of another shortwave trough
digging south-southeastward from the Pacific Northwest to the Desert
Southwest. In response to the ejecting Baja trough, lee cyclogenesis
is expected across southeast CO and northeast NM. This cyclone will
begin to develop eastward along a sharp baroclinic zone late in the
period, as cold air damming occurs across the High Plains.

...Northeast TX/southeast OK to TN/KY and the Deep South...
A broad warm sector has been established for many days from TX into
the Southeast with mid 60s to low 70s surface dew points, and
northward spread of this warm sector is expected through tonight
into southeast OK/AR/TN/southern KY. There is uncertainty regarding
the potential for open warm sector thunderstorm development with
minimal forcing for ascent and some lingering convective inhibition.
However, if a storm or two manage to become sustained later this
afternoon from central MS to northwest GA, the environment will
conditionally favor a supercell severe threat.

Otherwise, increasing low-level moisture along the consolidating
baroclinic zone and strengthening forcing for ascent primarily
through low-level warm theta-e advection will lead to increasing
storm coverage overnight from north TX/southeast OK east-northeast
across AR/TN/KY. Given deep-layer wind fields largely paralleling
the baroclinic zone, elevated convection on the cool side of the
boundary may pose a threat for sporadic severe hail and wind. Any
surface-based storms along or just south of the front will have the
potential to develop supercell structures and to produce a few
damaging gusts, isolated severe hail, and a couple tornadoes from
about 06-12Z.

$$

ACUS01 KWNS 011624
SWODY1
SPC AC 011623

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1023 AM CST Sat Jan 01 2022

Valid 011630Z - 021200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS TN...NORTHERN MS/AL...SOUTH-CENTRAL KY...

...SUMMARY...
Tornadoes, a couple of which could be strong, along with damaging
winds will be possible through tonight, especially across the
Tennessee Valley.

...Ark-La-Tex to the TN Valley...
Convection has persisted along a baroclinic zone demarcating the
northwest edge of the richer low-level moisture from the Ark-La-Tex
into western TN/KY. The convection has reinforced this boundary with
modest pressure rises behind it, resulting in it receding southeast
in the Mid-South. It is very unlikely to return north, given the
lack of appreciable cyclogenesis as a result of an expansive cold
air mass across the central U.S. that will undercut the stronger
forcing for ascent in advance of the primary shortwave trough over
the Four Corners. Even though the main surface cyclone will not be
intense and will develop farther away from the warm sector (in
tandem with an ejecting shortwave trough over KS/OK), strong
deep-layer wind fields and vertical shear will persist through the
day and into tonight in the warm sector across the TN Valley.

Given the persistence of the subtropical ridge over FL and only
glancing/small height falls through the day, much of the convection
may remain confined to the convection-reinforced frontal zone.
Still, there will be the potential for embedded supercells within a
broken band of storms along the front, and a lower chance for a
few supercells in the open warm sector along diffuse confluence
zones a little south of the front later this afternoon/evening.
Effective bulk shear of 60-70 kt and MLCAPE of 500-1500 J/kg will
conditionally support supercells capable of producing tornadoes,
damaging winds, and marginally severe hail. The prospects for a
couple strong tornadoes will likely hinge on pre-frontal supercell
development that is not entirely undercut by the surface front. This
is most likely from northern portions of MS/AL into middle TN where
effective SRH in excess of 300 m2/s2 should be common late this afternoon/evening. The frontal convection will spread southeast
through the overnight hours, with a gradually lessening severe
threat and shrinking warm sector centered on AL toward the end of
the period.

..Grams/Karstens.. 01/01/2022

$$