LIVE MAP (ABOVE) ... SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1251 AM CDT Sat Aug 05 2023
Valid 051200Z - 061200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS IN A CORRIDOR
FROM EASTERN COLORADO ACROSS PARTS OF KANSAS...OKLAHOMA...AND TOWARD
SOUTHWEST MISSOURI AND NORTHWEST ARKANSAS...
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER MUCH OF THE
PLAINS...AND FROM INDIANA INTO NORTHERN KENTUCKY...
...SUMMARY...
Severe thunderstorms producing damaging winds are expected from late
afternoon through evening over much of the central Plains. Scattered
severe storms will also be possible extending north across Nebraska
and South Dakota, with isolated severe storms possible from Indiana
southward toward Arkansas and western Tennessee.
...Synopsis...
A belt of moderate westerly winds aloft will exist over the central
Plains today, with an upper trough over the Dakotas. This trough
will shift southeastward through Sunday morning, with 500 mb
northwesterlies up to 50 kt persisting into KS and OK. A surface low
will be located over southeast SD at 00Z, with a cold front
extending southwestward across NE and into northeast CO. Farther
south, a secondary low is forecast over the TX Panhandle where steep
low-level lapse rates will develop with hot conditions. Low-level
moisture will contribute to a large area of moderate instability
across the region, but potential early day precipitation may
stabilize parts of the area early in the day.
Low-level winds will also increase late in the day east of the low
into MN and IA, and will result in increased shear. A conditional
severe risk may therefore exist, depending on instability. Another
area of enhanced low-level shear will be with an MCV which will
continue east across IL and IN, providing a focus for scattered
strong to severe storms during the late afternoon and early evening.
...Central Plains...
Early day precipitation is forecast over parts of KS, northern OK,
possibly extending into southern MO and northern AR, as storms move
eastward out of CO overnight. This will likely have stabilizing
effects for much of the day. Strong heating will occur just south of
there, from central OK across the TX Panhandle and into southern CO
and all over NM and west TX. This may also maintain moist but weak
easterly low-level flow which will aid storms over CO late in the
afternoon. Storms are expected to form over parts of the Front Range
around 20Z, and into southeast CO through early evening. An
additional area of likely development will be within the heated air
over the Panhandles and into western OK. Much of this area has a
strong outflow signal from the models, and damaging gusts appear
likely over the Enhanced Risk area. Corridors of gusts over 75 mph
are expected.
Increasing mid to high level winds will also elongate hodographs,
and favor significant hail with storms that remain cellular from the
Panhandles into western OK and southwest KS. Otherwise, substantial
outflow production from storm interactions will likely lead to
strong to severe winds over the region, persisting overnight across
KS, OK and perhaps into southwest MO/northern AR.
...Eastern SD/NE into southwest MN/western IA...
Daytime rain/storms may occur across northern SD into ND, beneath
the cool upper trough and where low-level convergence will remain
robust near and north of the low. Stronger afternoon activity is
likely to develop near the low, and may spread east as far as MN/IA
by evening. A plume of MUCAPE over 2000 J/kg may reach into
southeast SD, coincident with sufficient shear for a supercell or
two. Any brief/weak tornado threat will be limited due to weak winds
aloft, with most of the shear down low. Larger hail is more likely
into NE, where both CAPE and deep-layer shear will be stronger.
Damaging winds may also occur into the mid MO Valley.
...IL into IN...
An MCV now moving across MO will continue east across IL today,
reaching IN by late afternoon. Wind fields will be locally enhanced
by this system, resulting in a small area of supercell potential,
perhaps with isolated tornadoes. The tornado risk will be
conditional on the instability plume and possible precipitation
contamination. Even so, mid 70s F dewpoints will tend to counteract
cooling effects, with low-level turning of winds with height near
the MCV favoring rotation within the stronger storms. Severe storms
are most likely after about 20Z over eastern IL, extending into
central and southern IN through early evening. Models typically have
a difficult time providing proper low-level shear resolution this
far in advance with prominent MCVs.
..Jewell/Moore.. 08/05/2023
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