LIVE MAP (ABOVE) ... SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0714 AM CDT Tue Jul 11 2023
Valid 111300Z - 121200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND
EVENING EXTENDING FROM EASTERN MONTANA INTO PARTS OF THE NORTHERN
AND CENTRAL PLAINS....
...SUMMARY...
The greatest risk for severe storms on Tuesday will be centered over
portions of the northern and central Great Plains. Damaging winds
and large hail are the primary risks.
...Eastern MT into SD/NE...
Morning water vapor imagery shows a large upper ridge over the
southwest states, with rather strong northwest flow aloft extending
from the northern/Canadian Rockies across much of the northern
Plains and Midwest states. Relatively strong heating will occur this
afternoon over eastern MT, where temperatures in the mid 80s and
dewpoints in the 50s to lower 60s will combine with steep mid level
lapse rates to yield MLCAPE values of 1500-2500 J/kg. An upper
trough currently over northwest MT will emerge into the high plains
by mid-afternoon, promoting scattered thunderstorm development.
Forecast soundings across this region show favorable deep-layer
shear for discrete supercell storms capable of large/very large hail
and damaging wind gusts. Activity will move/develop eastward into
southwest ND and western SD during the evening, and eventually into
parts of NE with a continued severe threat.
...Eastern SD/NE into IA...
Scattered showers and thunderstorms are affecting the western
Dakotas this morning, in association with a subtle mid-level
shortwave trough. Model guidance varies considerably regarding the
evolution of this activity today, but at least some guidance
suggests that storms will intensify by mid-afternoon as daytime
heating becomes established. Forecast soundings appear favorable
for strong to severe storms, with sufficient vertical shear and
steep mid-level lapse rates to promote a conditional risk of large
hail and damaging wind gusts.
...Northeast TX into southern MS/AL...
A large nocturnal MCS is tracking southeastward across OK this
morning. This system and its associated MCV will progress into a
very moist and unstable airmass extending from northeast TX into the
central Gulf Coast region. Winds aloft are rather weak, and model
guidance is inconsistent on the evolution of the MCS. But it
appears likely that scattered strong storms will develop this
afternoon ahead of the MCV, with a risk of locally damaging wind
gusts in the stronger cells.
..Hart/Leitman.. 07/11/2023
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