Mesoscale Discussion 1013

Issued

Jun 13, 2017, 2:32 PM CDT (19:32 UTC)

Expired

Jun 13, 2017, 3:30 PM CDT

In force

58 min

Issued by

the Storm Prediction Center

Chance of a watch

95%

The Aberdeen radar (KABR), 134 km from the middle of the area, began a volume at 19:31 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

• Tornado Watch 323Jun 13, 3:15 PM CDT
• Severe Thunderstorm Watch 325Jun 13, 5:25 PM CDT
• Severe Thunderstorm Watch 326Jun 13, 5:55 PM CDT

138 
ACUS11 KWNS 131932
SWOMCD
SPC MCD 131932 
MNZ000-SDZ000-NDZ000-NEZ000-132030-

Mesoscale Discussion 1013
NWS Storm Prediction Center Norman OK
0232 PM CDT Tue Jun 13 2017

Areas affected...North-central Nebraksa...East-central South
Dakota...Southeast North Dakota

Concerning...Severe potential...Watch likely 

Valid 131932Z - 132030Z

Probability of Watch Issuance...95 percent

SUMMARY...A severe threat is likely to develop this afternoon from
central Nebraska north northeastward into southeastern North Dakota
and west-central Minnesota. Large hail and wind damage will be
possible after cells initiate but a tornado threat should also
develop as cells mature. A weather watch will likely be needed
across the region by 20Z.

DISCUSSION...The latest surface analysis shows a 999 mb low over
north-central Nebraska with a cold front extending
south-southwestward from the low. Surface winds are backed across
much of eastern South Dakota where low-level moisture is maximized
with surface dewpoints in the lower to mid 70s F. This is
contributing to a pocket of strong instability in eastern South
Dakota and northeastern Nebraska where the RAP is estimating MLCAPE
values in the 3000 to 4000 J/kg range. In addition, water vapor
imagery shows a shortwave trough over the central and northern
Rockies. A vorticity maxima associated with the shortwave trough is
analyzed by the RAP across western Nebraska. As this feature moves
across the central and northern Plains this afternoon, large-scale
ascent will support the development of numerous thunderstorms along
the cold front and to the northeast of the surface low into
southeastern North Dakota and west-central Minnesota.

Forecast soundings along this corridor show favorable wind profiles
for supercells with strong speed shear in the low to mid-levels with
0-6 km shear forecast to be in the 35 to 45 kt range. This combined
with very steep mid-level lapse rates exceeding 8.5 C/km across
parts of the MCD area will be favorable for large hail with
supercells. Hailstones of greater than 2 inches in diameter will be
possible within the strongest cores. Cells that do not form into
supercells may still be severe with a threat for hail and wind
damage. As the low-level jet increases in strength late this
afternoon and as the storms become mature, a tornado threat will
also be possible across the MCD area. The most favorable area for
tornado development could be across northeastern South Dakota,
southeastern North Dakota and west-central Minnesota.

..Broyles/Hart.. 06/13/2017

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...MPX...FGF...FSD...OAX...ABR...GID...BIS...LBF...
UNR...

LAT...LON   44779673 43899777 42009819 41229878 40989984 41040067
            41620126 42560114 44610060 45909999 46979834 47239723
            47129619 46629560 45949546 45129631 44779673

Mesoscale Discussions in South Dakota, 2017Mesoscale Discussions in Nebraska, 2017Mesoscale Discussions in North Dakota, 2017Every mesoscale discussion in 2017

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.