Alert archive / Iowa / Mesoscale Discussions in 2021
Mesoscale Discussion 1289
The Storm Prediction Center issued this mesoscale discussion at Jul 14, 2021, 8:35 PM CDT for 11 counties in Iowa. It was in force for 25 min.
The area
The outline as issued.
The facts
- Issued
- Jul 14, 2021, 8:35 PM CDT (01:35 UTC)
- Expired
- Jul 14, 2021, 9:00 PM CDT
- In force
- 25 min
- Issued by
- the Storm Prediction Center
- Concerning
- Tornado watch 378
Counties Benton County, IA, Black Hawk County, IA, Buchanan County, IA, Fayette County, IA, Grundy County, IA, Jasper County, IA, Linn County, IA, Marshall County, IA, Polk County, IA, Story County, IA, Tama County, IA
The radar
The Des Moines radar (KDMX), 111 km from the middle of the area, began a volume at 01:34 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 00:00Z, 1.6 hours before the alert went out and 178 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
- 2569 J/kg
- Mixed-layer CIN
- -10 J/kg
- Mixed-layer LCL
- 832 m above ground
- 0-6 km bulk shear
- 38 kt
- 0-1 km storm-relative helicity
- 253 m²/s²
- 0-3 km storm-relative helicity
- 346 m²/s²
- Significant tornado parameter
- 3.2
- Supercell composite
- 23.4
The text
As transmitted.
988
ACUS11 KWNS 150135
SWOMCD
SPC MCD 150135
IAZ000-150200-
Mesoscale Discussion 1289
NWS Storm Prediction Center Norman OK
0835 PM CDT Wed Jul 14 2021
Areas affected...Central and east-central Iowa
Concerning...Tornado Watch 378...
Valid 150135Z - 150200Z
The severe weather threat for Tornado Watch 378 continues.
SUMMARY...A storm or two may linger in southeastern portions of WW
378 beyond 9 PM CDT. Local extensions in time of the watch will
likely be needed as the environment will remain favorable for
tornadoes for another few hours.
DISCUSSION...While the storm mode has trended less discrete over the
last two hours, several embedded supercells have produced observed
tornadoes during that time. The environment just ahead of this
activity still remains favorable for tornadoes per the 00Z DVN
sounding and KDVN VWP. With the increase in the low-level jet this
evening, the environment will likely support tornadoes for a few
more hours. Given that some activity may linger beyond 9 PM CDT,
some local extensions in time of WW 378 will likely be needed.
..Wendt.. 07/15/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...DVN...ARX...DMX...
LAT...LON 41709407 42319326 42749236 42899184 42849159 42659145
42299145 41869158 41749182 41679287 41649384 41709407SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 14, 9:15 PM CDT | Mesoscale Discussion | SPC | Allamakee, Clayton, Clinton, Delaware, Dubuque, Jackson and 2 more | 90 min |
| Jul 14, 11:17 PM CDT | Mesoscale Discussion | SPC | Clinton, Muscatine, Scott | 58 min |
Nearby
Mesoscale 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.