Alert archive / Iowa / Mesoscale Discussions in 2003

Mesoscale Discussion 2187

August 19, 200338 counties in Iowa; Fillmore County, Mower County, Minnesota

The Storm Prediction Center issued this mesoscale discussion at Aug 19, 2003, 1:08 PM CDT for 38 counties in Iowa; Fillmore County, Mower County, Minnesota. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Aug 19, 2003, 1:08 PM CDT (18:08 UTC)
Expired: Aug 19, 2003, 3:15 PM CDT
In force: 2 hr
Issued by: the Storm Prediction Center

All 40 counties

Audubon County, IA, Benton County, IA, Black Hawk County, IA, Boone County, IA, Bremer County, IA, Buchanan County, IA, Butler County, IA, Calhoun County, IA, Carroll County, IA, Cerro Gordo County, IA, Chickasaw County, IA, Dallas County, IA, Fayette County, IA, Floyd County, IA, Franklin County, IA, Greene County, IA, Grundy County, IA, Guthrie County, IA, Hamilton County, IA, Hancock County, IA, Hardin County, IA, Howard County, IA, Humboldt County, IA, Jasper County, IA, Kossuth County, IA, Linn County, IA, Marshall County, IA, Mitchell County, IA, Palo Alto County, IA, Pocahontas County, IA, Polk County, IA, Story County, IA, Tama County, IA, Webster County, IA, Winnebago County, IA, Winneshiek County, IA, Worth County, IA, Wright County, IA, Fillmore County, MN, Mower County, MN

The radar

The Des Moines radar (KDMX), 107 km from the middle of the area, began a volume at 18:08 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 watches that followed

Watches SPC issued over any of the same counties within four hours of this discussion.

Severe Thunderstorm Watch 872Aug 19, 3:25 PM CDT

The nearest sounding before it

Minneapolis, MN (KMPX), launched 12:00Z, 6.1 hours before the alert went out and 243 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.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 98 J/kg
Mixed-layer CIN: -292 J/kg
Mixed-layer LCL: 1473 m above ground
0-6 km bulk shear: 44 kt
0-1 km storm-relative helicity: 128 m²/s²
0-3 km storm-relative helicity: 164 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

010 
ACUS11 KWNS 191809
SWOMCD
SPC MCD 191808 
IAZ000-MNZ000-192015-

MESOSCALE DISCUSSION 2187
NWS STORM PREDICTION CENTER NORMAN OK
0108 PM CDT TUE AUG 19 2003

AREAS AFFECTED...IA/SERN MN

CONCERNING...SEVERE THUNDERSTORM POTENTIAL 

VALID 191808Z - 192015Z

CONVECTIVE LINE DEVELOPING ACROSS WRN IA SHOULD CONTINUE TO
STRENGTHEN AS IT TRACKS NEWD. THE ACTIVITY WILL HAVE A POTENTIAL FOR
ISOLATED LARGE HAIL AND/OR DAMAGING WINDS. WW MAY BECOME NECESSARY
IN THE NEXT FEW HOURS.

CONVECTION IS CURRENTLY DEVELOPING IN AN AREA OF DEEP MOISTURE
CONVERGENCE CENTERED ACROSS SWRN IA. IN ADDITION...A WARM FRONT
EXTENDS NWWD FROM WRN IL ACROSS CNTRL IA. THE MOIST AXIS EXISTS TO
THE EAST OF THE STORMS WITH SFC DEWPOINTS IN THE LOWER TO MID 70S F.
MODERATE INSTABILITY HAS DEVELOPED ALONG THE MOIST AXIS WITH MLCAPE
OF 1000 TO 1500 J/KG. OBJECTIVE ANALYSIS SHOWS A BAND OF STRONGER
DEEP LAYER SHEAR ACROSS IA WITH 0-6 KM SHEAR AROUND 40 KT. AS THE
CONVECTION ORGANIZES AND MOVES EWD INTO A MORE FAVORABLE ENVIRONMENT
WITH STRONGER SHEAR AND BACKED LOW-LEVEL FLOW...A FEW SEVERE STORMS
WILL BE POSSIBLE THIS AFTERNOON. CONSIDERING THE DIRECTIONAL SHEAR
PROFILE AND MODERATE DEEP LAYER SHEAR...A MARGINAL SUPERCELL THREAT
SHOULD EXIST. A PLUME OF STEEPER LAPSE RATES WILL ENHANCE THE
POTENTIAL FOR ISOLATED LARGE HAIL. ISOLATED WET MICROBURSTS WILL
ALSO BE POSSIBLE CONSIDERING THE MOIST BOUNDARY LAYER AND MODERATE
SHEAR PRESENT.

..BROYLES.. 08/19/2003

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...DVN...ARX...MPX...DMX...FSD...

43169494 43579358 43909164 43039139 42039157 41609310
41349485 42229504

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Aug 19, 2:51 PM CDT	Mesoscale Discussion	SPC	Adair, Adams, Audubon, Carroll, Cass, Fremont and 10 more	84 min
Aug 19, 3:25 PM CDT	Severe Thunderstorm Watch	SPC	Adair, Adams, Audubon, Boone, Calhoun, Carroll and 33 more	6 hr
Aug 19, 6:10 PM CDT	Mesoscale Discussion	SPC	Adair, Adams, Audubon, Boone, Calhoun, Carroll and 30 more	95 min

Nearby

Mesoscale Discussions in Iowa, 2003 Mesoscale Discussions in Minnesota, 2003 Every mesoscale discussion in 2003

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.