620
ACUS01 KWNS 290550
SWODY1
SPC AC 290548

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1248 AM CDT Sat Jun 29 2024

Valid 291200Z - 301200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS IN THE UPPER OH
VALLEY...CENTRAL APPALACHIANS...AND LOWER GREAT LAKES...

...SUMMARY...
Across parts of the Upper Ohio Valley, central Appalachians, and
Lower Great Lakes, a couple tornadoes and scattered damaging winds
are possible. This appears centered from mid-afternoon to early
evening.

...OH Valley to the Northeast...
Have maintained the level 2-SLGT risk tornado and wind probabilities
as-is, with potential remaining evident for supercells embedded
within clusters/line segments later today. These threats will be
contingent on appreciable boundary-layer warming by peak heating,
amid poor mid-level lapse rates and pervasive cloudiness/early-day
convection within a low-level warm theta-e advection regime. This
regime will result in very rich boundary-layer moisture spreading
northeast across the entire OH Valley towards the Lower Great Lakes.
Where pockets of greater insolation can occur, confined corridors of
MLCAPE reaching 1500-2000 J/kg may develop. This should mostly be
offset westward from greater SRH and low-level hodograph enlargement
in NY/PA. But a corridor of overlap is possible, appearing centered
on the eastern OH to central PA vicinity. Midday to early afternoon
thunderstorm development should tend to be focused upstream of this,
ahead of remnant MCVs/convective outflows. As they impinge on the
warming boundary layer, potential will exist for sporadic strong to
localized severe gusts, in addition to a couple tornadoes through
early evening.

...Mid-MS Valley to northern OK...
The trailing portion of a cold front, attendant to a shortwave
trough and associated surface cyclone moving across the Upper Great
Lakes to western QC vicinity, should provide a focus for isolated to
widely scattered, late afternoon and evening thunderstorms. The more
probable convective development should occur along the northern OK
portion of the front, owing to hot temperatures south of it, but
will likely be within a weakly sheared environment. Richer
boundary-layer moisture should be displaced east over the
Ozarks/Mid-MS Valley, where deep-layer flow will be modestly
stronger, but with less confidence on convective coverage. Overall
scenario remains too nebulous to warrant higher than level 1-MRGL
risk for wind.

...NM/CO High Plains...
Isolated to scattered thunderstorms are expected during the late
afternoon and evening in a post-frontal upslope flow regime. Near 60
F surface dewpoints and steep mid-level lapse rates will support a
confined corridor of moderate buoyancy. While mid-level flow will be
weak, vertically veering wind profiles will support sufficient deep
shear for transient, slow-moving supercells developing off the
Sangre de Cristo Mountains. Isolated strong to marginally severe
gusts and hail will be possible.

...Northern MI...
Despite veered low-level winds ahead of the cold front and weak
mid-level lapse rates, boundary-layer heating should yield a plume
of weak buoyancy with MLCAPE of 500-1000 J/kg becoming common by
midday to early afternoon. Pronounced mid to upper-level speed shear
will support hodograph elongation. This may yield a supercell or two
capable of isolated severe hail and locally strong wind gusts in the
eastern U.P. to north Lower MI.

..Grams/Squitieri.. 06/29/2024

$$