ACUS02 KWNS 090558
SWODY2
SPC AC 090556
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1256 AM CDT Fri Aug 09 2024
Valid 101200Z - 111200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
THE SOUTH-CENTRAL HIGH PLAINS...
...SUMMARY...
Isolated severe thunderstorms (gusts, perhaps hail) are possible
during the afternoon into early evening over parts of the south-
central High Plains.
...Synopsis...
In mid/upper levels, the persistent Southwestern ridging that is
being weakened by a monsoonal trough will redevelop a closed high
over central/west TX through day 2. A height weakness will remain
from parts of AZ across the Four Corners to southern CO, through
which small, collectively generated/enhanced vorticity lobes should
move slowly. Farther north, a somewhat blocky, slow-moving pattern
will be characterized by gradual breakdown of a Rex configuration
now over western Canada, with an undercutting stream of nearly zonal
flow across the Northwest and north-central Plains. This will
converge into a belt of cyclonic flow around a substantial mid/upper
cyclone -- now centered over the northern Lake Superior/Lakehead
region of northern ON. Through the day-2 period, the low should
pivot across northeastern ON to western QC south and southeast of
James Bay, as a series of small shortwaves rotate through the
cyclone's western/southern sectors.
In response to these developments, the rapidly decaying, open-wave
remnants of Debby should be absorbed into a baroclinic zone and
ejecting away from the Northeast by the start of this period,
leaving behind a cold front from central New England southwestward
down the Piedmont in NC/SC to central GA and coastal LA. This
boundary should become a diffuse warm front from LA northwestward
across southeast/west-central TX to east-central NM. By 00Z, the
front should extend from the near the Hampton Roads area
southwestward over southern GA and the western FL Panhandle, arching
northwestward from southern LA across the TX Panhandle and into a
low over southeastern CO/western OK Panhandle region.
...Central to south-central High Plains...
Widely scattered to scattered thunderstorms are possible in a
corridor extending southeastward from near the low, along the front,
and off the nearby Raton Mesa and Palmer Divide. Mid/upper support
may be present in the form of a small perturbation or two migrating
from the Four Corners region. Activity should develop during
mid/late afternoon as boundary-layer convergence near the low and
heating of elevated terrain combine to remove MLCINH, along the
northwestern fringe of a plume of returning low-level moisture along
and south of the warm front. Forecast soundings indicate surface
dewpoints in the mid 50s to low 60s and a deep troposphere will
support MLCAPE in the 1500-2500 J/kg range, atop a well-mixed
subcloud layer. This area will have generally weak low-level
speeds, but strong veering of winds with height under the southern
fringe of favorable mid/upper winds, with 25-40-kt effective-shear
magnitudes. As such, organized multicells and perhaps brief
supercells are possible, with isolated severe gusts and hail.
Farther north/northwest across northeastern CO and central/eastern
WY, an isolated, high-based, strong-severe thunderstorm cannot be
ruled out -- moving out of higher terrain of the Bighorns, Laramie
Range or northern Front Range/Cheyenne Ridge region -- beneath
stronger mid/upper flow and greater deep shear. However, lack of
more-robust moisture, and convective-coverage uncertainty, preclude
an unconditional outlook at this time.
..Edwards.. 08/09/2024
$$
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