Alert archive / Wisconsin / Mesoscale Discussions in 2018
Mesoscale Discussion 1413
The Storm Prediction Center issued this mesoscale discussion at Sep 2, 2018, 3:47 PM CDT for 5 counties in Illinois; 16 counties in Wisconsin. It was in force for 118 min.
The area
The outline as issued.
The facts
- Issued
- Sep 2, 2018, 3:47 PM CDT (20:47 UTC)
- Expired
- Sep 2, 2018, 5:45 PM CDT
- In force
- 118 min
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 20%
All 21 counties
Boone County, IL, Jo Daviess County, IL, McHenry County, IL, Stephenson County, IL, Winnebago County, IL, Columbia County, WI, Dane County, WI, Dodge County, WI, Fond du Lac County, WI, Grant County, WI, Green County, WI, Iowa County, WI, Jefferson County, WI, Kenosha County, WI, Lafayette County, WI, Milwaukee County, WI, Rock County, WI, Sauk County, WI, Walworth County, WI, Washington County, WI, Waukesha County, WI
The radar
The Milwaukee radar (KMKX), 63 km from the middle of the area, began a volume at 20:46 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.
The nearest sounding before it
Davenport, (KDVN), launched 12:00Z, 8.8 hours before the alert went out and 181 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.
- Mixed-layer CAPE
- 20 J/kg
- Mixed-layer CIN
- -242 J/kg
- Mixed-layer LCL
- 1345 m above ground
- 0-6 km bulk shear
- 38 kt
- 0-1 km storm-relative helicity
- 7 m²/s²
- 0-3 km storm-relative helicity
- 58 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.1
The text
As transmitted.
207
ACUS11 KWNS 022048
SWOMCD
SPC MCD 022047
ILZ000-WIZ000-IAZ000-022245-
Mesoscale Discussion 1413
NWS Storm Prediction Center Norman OK
0347 PM CDT Sun Sep 02 2018
Areas affected...Southern WI...Far Northern IL
Concerning...Severe potential...Watch unlikely
Valid 022047Z - 022245Z
Probability of Watch Issuance...20 percent
SUMMARY...Isolated hail and/or damaging wind gusts are possible this
afternoon. A watch is not currently anticipated but convective
trends will be monitored.
DISCUSSION...Thunderstorm coverage will continue to increase across
the region as outflow from antecedent storms continues to push
southeastward. This lift will be augmented by modest large scale
forcing for ascent attendant to a shortwave trough progressing
through southwesterly flow aloft into the area. Mid-level lapse
rates are not particularly steep but a moderate to strongly unstable
airmass has still developed, largely a result of ample low-level
moisture. The low to mid-level flow across the region is largely
unidirectional but enough speed shear exists to support a few more
organized storms. Marginally severe hail is possible within the
stronger, more persistent updrafts. Storm interactions may also
result in brief updrafts strong enough to produce some hail. A
damaging wind gusts or two is also possible as a result of
water-loaded downdrafts. Even so, overall severe coverage is
expected to remain rather isolated, leading to lower watch
probabilities.
..Mosier/Guyer.. 09/02/2018
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...LOT...MKX...DVN...ARX...
LAT...LON 43189073 43598985 43888839 43408781 43008772 42158793
42108997 42499078 43189073SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 1, 10:27 PM CDT | Mesoscale Discussion | SPC | Carroll, Henry, Mercer, Rock Island, Whiteside | 63 min |
Nearby
Mesoscale Discussions in Wisconsin, 2018Mesoscale Discussions in Illinois, 2018Every mesoscale discussion in 2018
Sources
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.