SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0258 PM CDT Tue Mar 29 2022
Valid 292000Z - 301200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM PARTS OF THE
LOWER MISSOURI VALLEY TO CENTRAL TEXAS...
...SUMMARY...
Severe thunderstorms are expected this evening and tonight from the
lower Missouri Valley region to central Texas. Damaging gusts,
severe hail, and a few tornadoes are all possible.
...20Z Update...
Convection should initiate across parts of south-central KS near the
triple point around 22-00Z. Increasing but still relatively modest
low-level moisture, steep mid-level lapse rates, and strong
deep-layer shear should support organized thunderstorms across this
region. Severe hail and damaging winds will be a threat with any
supercells that can develop and spread into eastern KS/western MO
and vicinity this evening. There will also be a window during the
mid to late evening for a few tornadoes as low-level shear increases
with a strengthening low-level jet, but before the boundary layer
stabilizes. Have expanded the 5% tornado area a little to account
for this potential. Also nudged severe probabilities westward
slightly in western OK to where recent high-resolution guidance
suggests storms may initiate along the dryline by 01-02Z.
Across northeast NE/northwest IA and vicinity, have compressed
severe hail probabilities to where destabilization appears most
likely to occur by later this evening. The northward extent of the
severe threat should quickly wane as convection moves northeastward
into a less unstable airmass.
Thunderstorms are still expected to develop mainly after 00Z this
evening across parts of west/central TX as the cap along the dryline
slowly erodes and large-scale ascent associated with an upper trough
overspreads this region. Damaging winds should be the main threat as
convection quickly grows upscale, but some large hail may occur
within the first few hours of convective initiation given the
presence of steep mid-level lapse rates and strong effective bulk
shear.
..Gleason.. 03/29/2022
.PREV DISCUSSION... /ISSUED 1124 AM CDT Tue Mar 29 2022/
A deep upper low over western AZ is tracking eastward across the
southern Rockies today, with the primary upper jet max forecast to
rotate through the base of the trough and across much of the
southern Plains tonight. As this occurs, three different regimes of
strong/severe convection are expected.
...Eastern NE/Western IA...
The main surface low is forecast to deepen as it moves into
east-central NE by early evening. Southeasterly low-level winds
will help transport a narrow corridor of 50s dewpoints and
surface-based instability into parts of eastern NE and western IA,
where CAM guidance is in agreement that scattered thunderstorms will
form. These storms will only briefly be surface-based before they
track northward across the warm front into a cooler/stable
boundary-layer. There is a chance of a brief tornado or two before
the storms become elevated, after which the main threat will be hail
and gusty winds.
...Eastern KS/Western MO/Southern IA...
A surface dryline is expected to become established later today from
western OK into central KS. Temperatures in the 80s and dewpoints
rising into the mid/upper 50s along the boundary will help to weaken
the cap and lead to scattered thunderstorms - mainly after 23z.
This activity should persist through the evening as cooling aloft
and the primary cold front move into the region. Initial storms may
be supercellular with all severe hazards possible. A gradual
evolution to a QLCS is expected by mid-evening with damaging winds
and isolated mesovortex spin-ups being the main threats.
...Southern OK into West-central TX...
Surface temperatures over 90F are expected just west of the dryline
over southwest OK and west-central TX this afternoon, resulting in a
narrow corridor of weak cap. A few thunderstorms may form in this
area, capable of large hail and damaging winds. Forecast soundings
show a formidable cap is present as storms evolve off the dryline
and into the warm sector. Increasing large-scale forcing will
arrive after dark, helping to weaken the cap and foster more
widespread convection. However, linear convective modes are likely
by that time with locally damaging wind gusts the main threat.
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