LIVE MAP (ABOVE) ... SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1129 AM CDT Sat Jul 01 2023
Valid 011630Z - 021200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS MID-MS AND
LOWER OH VALLEY...
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS PART OF THE
PERMIAN BASIN IN WEST TX...
...SUMMARY...
Scattered severe thunderstorms are most likely across parts of the
Mid-Mississippi and Lower Ohio Valleys through early evening.
Damaging winds and a couple tornadoes will be the main hazards.
...Mid MS/OH Valleys...
A modestly amplified shortwave trough over western NE/KS will
progress into IA/MO by tonight, as embedded, convectively enhanced
perturbations rotate around its southern and eastern periphery. One
such perturbation near the Ozark Plateau will aid in scattered
thunderstorm development as it impinges on the Mid-MS Valley. This
activity will form within a pronounced differential boundary-layer
heating/buoyancy gradient amid large MLCAPE of 3000-4000 J/kg in the
undisturbed warm sector over the Mid-South. Within a belt of 35-45
kt mid-level west-southwesterlies, initial supercells/clusters
congealing into a forward-propagating linear MCS appears probable.
Large hail will be possible, mainly early, but the predominant
threat should be damaging wind swaths towards the central OH Valley.
A couple of embedded tornadoes will also be possible, mainly focused
along/just north of the residual outflow boundary arcing west from
ongoing convection over central KY.
...Permian Basin...
Weak convergence along a convectively enhanced cold front, in
combination with a narrow corridor of stronger boundary-layer
heating between the front and thicker clouds within the
southern-stream closer to the Big Bend, should yield a rather
confined corridor of MLCAPE approaching 2500 J/kg in the late
afternoon. Deep-layer shear will be modest and convection will
probably be slow-moving to the south-southeast but a few severe
outflow gusts and isolated large hail will be possible.
...Lee of the central/southern Appalachians...
There is some potential for intensification of isolated to scattered
storms along residual outflows and a weak surface trough just east
of the Blue Ridge, as the low levels warm this afternoon. Mid-level
lapse rates will remain weak north of southwest VA, while diffluent
mid-level flow in the lee of the central Appalachians will generally
hold effective bulk shear below 25 kt north of southwest VA.
Localized damaging winds and perhaps marginally severe hail will be
the main threats.
...PA/NY...
Subtle/embedded perturbations will move over the lower Great Lakes
region today, around the southern periphery of the shortwave trough
centered on the Ontario-Quebec border. Surface heating in cloud
breaks and boundary-layer dew points in the 60s will support MLCAPE
of 1000-1500 J/kg east of the influence of the Lower Great Lakes.
Mid-level lapse rates will not be steep, but some modest enhancement
to mid-upper flow could be sufficient for a few semi-organized
clusters capable of producing isolated wind damage for a few hours
centered on late afternoon.
...Southern MT to ND...
Though forcing for ascent will be weak, at least isolated
thunderstorm development will be possible this afternoon/evening
from edge of the higher terrain in southern MT northeastward along a
weak pre-frontal trough into ND. Surface heating/deep mixing will
drive inverted-V profiles with MLCAPE of 500-1500 J/kg. Weak flow
supports relatively slow-moving cells/clusters capable of producing
isolated strong-severe outflow gusts.
..Grams/Smith.. 07/01/2023
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