SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0233 PM CDT Wed May 04 2022
Valid 042000Z - 051200Z
...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS FROM THE
SOUTHEAST TEXAS PANHANDLE AND NORTHWEST TEXAS ACROSS MUCH OF
OKLAHOMA...
...SUMMARY...
Numerous severe thunderstorms are expected across parts of the
southern Great Plains this afternoon through tonight. A few strong
tornadoes and giant hail is most probable across the southeast Texas
Panhandle into portions of southwest Oklahoma and north Texas. Wind
damage as well as tornadoes are also possible across the remainder
of central and eastern Oklahoma through tonight.
...Eastern TX Panhandle/South Plains into much of OK...
The Moderate Risk has been expanded eastward across a large portion
of OK, as the air mass continues to destabilize and remain free of
storms. Visible imagery continues to show pockets of heating, and
increasing CU fields near the Red River. Surface observations show
an unbroken plume of 68-70 F dewpoints now into southern OK, with
GPS water vapor sensors indicating a deepening moist boundary layer
with values increasing to over 1.50" over northwest TX.
Midday soundings reveal a capping inversion below 700 mb which is
helping to maintain the pristine air mass and guard against early
contamination. This inversion may also help to subdue the number of
storms later today across OK and northern TX. Any supercell over the
warm sector will have the potential to produce a strong tornado,
aided by midlevel lapse rates near 8 C/km and dewpoints of 68 F or
greater. Later this evening, storms moving out of the Panhandle may
eventually merge into a severe MCS with significant wind damage
potential. In addition, further supercell develop may occur tonight
along the baroclinic zone extending eastward across OK.
Farther west into the TX Panhandle and South Plains, rapid
destabilization continues, beneath cooler air aloft. Supercells
producing very large damaging hail are likely, with a threat of
strong tornadoes as supercells interact with increasing low-level
shear to the east.
See mesoscale discussions 640, 642, 643 for more information.
..Jewell.. 05/04/2022
.PREV DISCUSSION... /ISSUED 1122 AM CDT Wed May 04 2022/
...Southern Great Plains...
Complicated forecast today/tonight as a broad/destabilizing warm
sector enlarges as a warm front advances northward today.
Considerable forecast uncertainty remains evident for a multitude of
possible scenarios, some of which differ both spatially in terms of
severe hazard and intensity. Nonetheless, with the lack of morning
convection across northwest TX into the TX Panhandle, thinking is
this area will remain void of convection through the midday/early
afternoon. Consequently, it seems a categorical Moderate Risk is
warranted for dryline/triple point storms.
Visible-satellite imagery late this morning shows a cirrus canopy
across much of the outlook area. A warm front is rapidly moving
northward across north TX with upper 60s F dewpoints reaching the
Red River as of 16z. A destabilizing boundary layer beneath a
capping inversion, which seems likely to hold through the early
afternoon, will become quite unstable by peak heating with 3000-4000
J/kg MLCAPE forecast over northwest TX by 4pm. The RAP/HRRR seems
to have the best handle on morning storm activity compared to the
ARW and associated CAM models. In general, model guidance indicates
storms will develop over the TX Panhandle during the mid-late
afternoon with more widely spaced thunderstorms farther south along
the dryline. Very steep 700-500 mb lapse rates, enlarged low-level
hodographs via easterly component to low-level flow, and long
hodographs all suggest discrete supercells will be the preferred
mode over the TX Panhandle into northwest TX late this afternoon.
Very large to giant hail (potentially 3+ inches in diameter) and a
few strong tornadoes are possible during the late afternoon into the
early evening as this activity moves into parts of western OK/far
western north TX. Less certain but a plausible scenario involves
free warm sector development farther east across parts of OK and
perhaps north TX. A potentially significant tornado risk could
develop if discrete supercells were to develop within an
increasingly moist/strongly sheared environment during the late
afternoon/early evening.
By early to mid evening, the strengthening of a southerly LLJ and
coalescing of storms/outflow will probably lead to the development
of a severe MCS moving east across parts of OK. Severe gusts,
possibly greater than 65 kt, and tornadoes will become the primary
severe hazards with time. As this activity approaches the western
part of the Ozarks, a lessening in the severe risk is anticipated
late overnight.
...Southeast VA and the Carolinas...
Not much change from the previous forecast in the overall
thunderstorm scenario for VA/Carolinas. A low-amplitude shortwave
trough over the Lower Great Lakes will move east into southern New
England this evening. To the south of this wave, a cold front will
push southeast across the Lower Mid-Atlantic into the Carolinas.
Convergence along the cold front and coastal sea breezes should
support scattered thunderstorms this afternoon. While deep-layer
shear will be modest, it should be adequate for multicells capable
of isolated severe hail and damaging winds. Convection should
largely shift offshore and/or weaken after dusk.
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