Alert archive / Iowa / Mesoscale Discussions in 2012
Mesoscale Discussion 658
The Storm Prediction Center issued this mesoscale discussion at May 2, 2012, 2:02 AM CDT for 28 counties in Iowa. It was in force for 58 min.
The area
The outline as issued.
The facts
- Issued
- May 2, 2012, 2:02 AM CDT (07:02 UTC)
- Expired
- May 2, 2012, 3:00 AM CDT
- In force
- 58 min
- Issued by
- the Storm Prediction Center
All 28 counties
Adair County, IA, Adams County, IA, Audubon County, IA, Boone County, IA, Carroll County, IA, Cass County, IA, Clarke County, IA, Dallas County, IA, Greene County, IA, Guthrie County, IA, Hamilton County, IA, Hardin County, IA, Jasper County, IA, Lucas County, IA, Madison County, IA, Mahaska County, IA, Marion County, IA, Marshall County, IA, Monroe County, IA, Montgomery County, IA, Polk County, IA, Pottawattamie County, IA, Poweshiek County, IA, Shelby County, IA, Story County, IA, Union County, IA, Warren County, IA, Webster County, IA
The radar
The Des Moines radar (KDMX), 48 km from the middle of the area, began a volume at 07:03 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
Omaha, NE (KOAX), launched 00:00Z, 7.0 hours before the alert went out and 185 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
- 1502 J/kg
- Mixed-layer CIN
- -30 J/kg
- Mixed-layer LCL
- 1477 m above ground
- 0-6 km bulk shear
- 36 kt
- 0-1 km storm-relative helicity
- 75 m²/s²
- 0-3 km storm-relative helicity
- 122 m²/s²
- Significant tornado parameter
- 0.4
- Supercell composite
- 5.2
The text
As transmitted, in the capitals the NWS used until 2016.
158
ACUS11 KWNS 020702
SWOMCD
SPC MCD 020702
IAZ000-020800-
MESOSCALE DISCUSSION 0658
NWS STORM PREDICTION CENTER NORMAN OK
0202 AM CDT WED MAY 02 2012
AREAS AFFECTED...CENTRAL IA
CONCERNING...SEVERE THUNDERSTORM WATCH 224...
VALID 020702Z - 020800Z
THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 224
CONTINUES.
SUMMARY...THREAT FOR DAMAGING WINDS AND AN ISOLATED/BRIEF TORNADO
CONTINUES ACROSS CENTRAL IA -- PARTICULARLY INVOF THE DES MOINES
AREA.
DISCUSSION...LATEST RADAR IMAGERY SHOWS A COMPLEX BOWING SEGMENT
WITHIN THE BROADER LINE MOVING INTO DALLAS AND STORY COUNTY
ATTM...WITH THE STRONGEST SURGE LIKELY TO REMAIN JUST N OF DSM.
ALONG THIS ENHANCED PORTION OF THE LINE...WINDS IN EXCESS OF 55 KT
ARE BEING OBSERVED ROUGHLY 1500 AGL PER LATEST VWP DATA...AND SMALL
CIRCULATION SPIN-UPS ALONG THE GUST FRONT ARE ALSO EVIDENT.
WHILE THE ACCELERATION IN THIS PORTION OF THE LINE REPRESENTS A
LOCAL RAMP-UP IN SEVERE WEATHER POTENTIAL...IT APPEARS THAT THIS
THREAT SHOULD REMAIN RELATIVELY SHORT-LIVED...AS THE BOUNDARY-LAYER
AIRMASS ACROSS ERN IA -- ON THE ERN SIDE OF THE NW-SE FRONT --
REMAINS STABLE. THUS -- WHILE STORMS CONTINUE THROUGH THE NARROW
INSTABILITY AXIS...SEVERE THREAT WILL CONTINUE...BUT EXPECT AN
OVERALL DECREASE WITH TIMES AS UPDRAFTS CROSS THE SURFACE FRONT AND
BEGIN TO BECOME ELEVATED.
..GOSS.. 05/02/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...DMX...OAX...
LAT...LON 40869530 41239587 42379458 42669321 41859250 40939247
40849401 40869530SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 1, 7:30 PM CDT | Mesoscale Discussion | SPC | Buena Vista, Cherokee, Harrison, Ida, Monona, Plymouth and 1 more | 2 hr |
| May 1, 9:18 PM CDT | Severe Thunderstorm Watch | SPC | Adair, Adams, Audubon, Black Hawk, Boone, Buena Vista and 54 more | 7 hr |
| May 1, 11:08 PM CDT | Mesoscale Discussion | SPC | Adair, Adams, Audubon, Black Hawk, Boone, Bremer and 47 more | 2 hr |
| May 2, 3:34 PM CDT | Mesoscale Discussion | SPC | Clay, Dickinson, Emmet, Lyon, O'Brien, Osceola and 2 more | 86 min |
Nearby
Mesoscale Discussions in Iowa, 2012Every mesoscale discussion in 2012
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.