Alert archive / Wisconsin / Mesoscale Discussions in 2021
Mesoscale Discussion 1609
The Storm Prediction Center issued this mesoscale discussion at Aug 26, 2021, 1:12 PM CDT for Allamakee County, Winneshiek County, Iowa; Fillmore County, Houston County, Winona County, Minnesota; 7 counties in Wisconsin. It was in force for 93 min.
The area
The outline as issued.
The facts
- Issued
- Aug 26, 2021, 1:12 PM CDT (18:12 UTC)
- Expired
- Aug 26, 2021, 2:45 PM CDT
- In force
- 93 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch unlikely
- Chance of a watch
- 20%
Counties Allamakee County, IA, Winneshiek County, IA, Fillmore County, MN, Houston County, MN, Winona County, MN, Crawford County, WI, Jackson County, WI, La Crosse County, WI, Monroe County, WI, Richland County, WI, Trempealeau County, WI, Vernon County, WI
The radar
The La Crosse radar (KARX), 30 km from the middle of the area, began a volume at 18:15 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, 6.2 hours before the alert went out and 226 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
- 458 J/kg
- Mixed-layer CIN
- -249 J/kg
- Mixed-layer LCL
- 817 m above ground
- 0-6 km bulk shear
- 9 kt
- 0-1 km storm-relative helicity
- 14 m²/s²
- 0-3 km storm-relative helicity
- -15 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
761
ACUS11 KWNS 261813
SWOMCD
SPC MCD 261812
WIZ000-IAZ000-MNZ000-261945-
Mesoscale Discussion 1609
NWS Storm Prediction Center Norman OK
0112 PM CDT Thu Aug 26 2021
Areas affected...Extreme southeast MN/northeast IA...Southwest WI
Concerning...Severe potential...Watch unlikely
Valid 261812Z - 261945Z
Probability of Watch Issuance...20 percent
SUMMARY...Some increase in the damaging wind threat is possible this
afternoon ahead of a convective line. Watch issuance is currently
considered unlikely.
DISCUSSION...At 18Z, a line of thunderstorms is gradually
intensifying across northeast IA into southeast MN, along a remnant
outflow from the decaying MCS across central IA. While substantial
cloud cover is noted downstream into southwest WI, some modest
heating/destabilization has occurred, especially near and south of a
surface boundary draped from southern WI into southwest MN.
Continued modest destabilization and steepening of low-level lapse
rates may allow for an increasing damaging wind potential with this
line as it moves northeastward. Relatively modest deep-layer
flow/shear (as noted in KARX VWP) should keep organization
relatively limited, so watch issuance is currently considered
unlikely.
..Dean/Dial.. 08/26/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...MKX...ARX...
LAT...LON 43859258 44309147 44349064 43999015 43658999 43199019
43059063 42979113 42959185 43199211 43419235 43859258SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 26, 7:37 AM CDT | Mesoscale Discussion | SPC | Adair, Audubon, Boone, Buena Vista, Calhoun, Carroll and 20 more | 83 min |
| Aug 26, 9:40 AM CDT | Mesoscale Discussion | SPC | Adair, Adams, Appanoose, Benton, Boone, Clarke and 25 more | 95 min |
| Aug 26, 5:34 PM CDT | Mesoscale Discussion | SPC | Buena Vista, Cherokee, Clay, Crawford, Harrison, Ida and 9 more | 116 min |
| Aug 26, 8:36 AM CDT | Mesoscale Discussion | SPC | Big Stone, Lac qui Parle | 84 min |
| Aug 26, 9:05 AM CDT | Severe Thunderstorm Watch | SPC | Big Stone, Chippewa, Kandiyohi, Lac qui Parle, Lincoln, Lyon and 11 more | 4 hr |
| Aug 26, 10:43 AM CDT | Mesoscale Discussion | SPC | Lac qui Parle, Lincoln, Lyon, Murray, Pipestone, Redwood and 1 more | 92 min |
| Aug 26, 1:53 PM CDT | Mesoscale Discussion | SPC | Carver, Dakota, Goodhue, Hennepin, Le Sueur, Ramsey and 3 more | 97 min |
Nearby
Mesoscale Discussions in Wisconsin, 2021Mesoscale Discussions in Minnesota, 2021Mesoscale Discussions in Iowa, 2021Every mesoscale discussion in 2021
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.