SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0255 PM CDT Wed Jun 29 2022
Valid 292000Z - 301200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF SOUTH DAKOTA THROUGH THIS EVENING....
...SUMMARY...
Intense thunderstorm gusts are likely through this evening over
parts of the Dakotas.
...20z Update...
An upgrade to an Enhanced risk (level 3 of 5), mainly for swaths of
damaging gusts, has been included across parts of central/northern
SD with the 20z update. Additionally, the Slight risk has been
expanded southward into parts of northern NE, and across part of
central ND. While instability remains somewhat modest across the
northern Plains, strong heating has allowed very steep low-level
lapse rates to develop. Additionally, DCAPE values greater than 1200
J/kg are noted in latest mesoanalysis. Forecast soundings indicated
favorable thermodynamic profiles supporting intense downdrafts and
thunderstorm outflows. Effective shear diminishes with southward
extent into the central Plains, but will favor organized convection
across SD, where clusters/bowing segments are expected. Latest CAMs
and machine learning guidance, couple with current observations
suggest severe gusts are possible from north-central NE into SD and
eastern ND/western MN through this evening. A few gusts greater than
75 mph possible from central into northeast SD. For more details
concerning short term evolution of severe convection, reference MCD
1304.
..Leitman.. 06/29/2022
.PREV DISCUSSION... /ISSUED 1112 AM CDT Wed Jun 29 2022/
...Northern/Eastern ND...
Visible satellite imagery shows a cluster of high-based showers and
thunderstorms over northern MT. This activity is associated with a
subtle mid-level shortwave trough and jet streak. Several CAM
solutions suggest one or more intense thunderstorms form later today
as this feature moves into northern ND. Forecast soundings show
moderate CAPE values and sufficient vertical shear for supercell
structures capable of large hail. If these storms form, they could
persist for several hours and track eastward into northeast
ND/northwest MN before weakening.
...WY/NE/Dakotas...
A broad upper ridge is present today over the central
Rockies/Plains, with the southern fringe of stronger westerlies
extending from northern UT into WY/NE/SD. A plume of mid-level
moisture is evident in water vapor imagery over parts of WY/CO,
which is likely to result in scattered high-based thunderstorms this
afternoon over the central/northern High Plains. Hot surface
temperatures over 100F will yield inverted-v profiles with
substantial downdraft potential. Sufficiently strong westerly flow
aloft and associated momentum transfer potential will aid in the
risk of locally gusty/damaging wind gusts through the afternoon and
early evening.
...Eastern NY into New England...
A upper level trough over the Great Lakes region will track eastward
into the northeast states this afternoon, with cool mid-level
temperatures and large scale ascent overspreading parts of NY/New
England. Strong daytime heating in this area will result in steep
low-level lapse rates, while dewpoints in the 50s yield MLCAPE
values of around 500 J/kg. A few strong/severe storms are possible
over southern Quebec, with uncertainty how far south storms will
develop. Will maintain the existing MRGL risk area for the
conditional potential for locally strong/damaging winds in storms
that can develop.
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