Alert archive / Iowa / Mesoscale Discussions in 2009

Mesoscale Discussion 1663

July 24, 200934 counties in Iowa

The Storm Prediction Center issued this mesoscale discussion at Jul 24, 2009, 6:38 PM CDT for 34 counties in Iowa. It was in force for 97 min.

The area

The outline as issued.

The facts

Issued: Jul 24, 2009, 6:38 PM CDT (23:38 UTC)
Expired: Jul 24, 2009, 8:15 PM CDT
In force: 97 min
Issued by: the Storm Prediction Center

All 34 counties

Adair County, IA, Adams County, IA, Appanoose County, IA, Audubon County, IA, Boone County, IA, Calhoun County, IA, Carroll County, IA, Cass County, IA, Clarke County, IA, Crawford County, IA, Dallas County, IA, Decatur County, IA, Greene County, IA, Grundy County, IA, Guthrie County, IA, Hamilton County, IA, Hardin County, IA, Jasper County, IA, Lucas County, IA, Madison County, IA, Marion County, IA, Marshall County, IA, Monroe County, IA, Montgomery County, IA, Page County, IA, Polk County, IA, Ringgold County, IA, Shelby County, IA, Story County, IA, Taylor County, IA, Union County, IA, Warren County, IA, Wayne County, IA, Webster County, IA

The radar

The Des Moines radar (KDMX), 62 km from the middle of the area, began a volume at 23:37 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 12:00Z, 11.6 hours before the alert went out and 164 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: 851 J/kg
Mixed-layer CIN: -316 J/kg
Mixed-layer LCL: 1683 m above ground
0-6 km bulk shear: 31 kt
0-1 km storm-relative helicity: 127 m²/s²
0-3 km storm-relative helicity: 155 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.1

Open this sounding in Storm Lab

The text

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

000 
ACUS11 KWNS 242338
SWOMCD
SPC MCD 242338 
IAZ000-MOZ000-250115-

MESOSCALE DISCUSSION 1663
NWS STORM PREDICTION CENTER NORMAN OK
0638 PM CDT FRI JUL 24 2009

AREAS AFFECTED...CENTRAL/SOUTHERN IA AND FAR NORTHERN MO

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

VALID 242338Z - 250115Z

MONITORING FOR SIGNS OF INCREASING DEEP CONVECTIVE DEVELOPMENT
ACROSS IA EARLY THIS EVENING. ADDITIONAL/IMMINENT DEVELOPMENT WOULD
LIKELY PROMPT A WATCH ISSUANCE.

REMOVED FROM THE MORE APPRECIABLE LARGE SCALE FORCING FOR ASCENT
OVER THE UPPER MISSISSIPPI RIVER VALLEY...STORMS HAVE STRUGGLED TO
DEVELOP THUS FAR WEST-SOUTHWESTWARD ALONG SURFACE FRONTAL
ZONE/PREFRONTAL TROUGH ANGLING NORTHEAST-SOUTHWESTWARD ACROSS IA.
ACCORDINGLY...ASSOCIATED CU FIELD HAS REMAINED RELATIVELY FLAT SINCE
MID AFTERNOON PER VISIBLE SATELLITE IMAGERY...ALTHOUGH A RECENT
TREND OF MODEST VERTICAL DEVELOPMENT HAS BEEN NOTED ACROSS PORTIONS
OF NORTH CENTRAL TO NORTHEAST IA...MAINLY IMMEDIATELY WEST OF
EXISTING TORNADO WATCH 619. WITH AROUND 70F SURFACE DEWPOINTS AND A
WEAKLY CAPPED/MODERATE TO STRONG UNSTABLE BOUNDARY LAYER IN
PLACE...FRONTAL CONVERGENCE/AT LEAST GLANCING LARGE SCALE FORCING
FOR ASCENT MAY PROVE SUFFICIENT FOR AN INCREASING SEVERE THREAT THIS
EVENING ACROSS IA...WITH SEVERE HAIL/DAMAGING WINDS AS THE PRIMARY
RISKS. LATEST SREF MULTI-MEMBER GUIDANCE...AND VARIOUS 12Z HIGH-RES
4KM MODELS SUCH AS WRF-NMM/NSSL/ARW...ARE STRONGLY SUPPORTIVE OF
INCREASING/SCATTERED TSTM DEVELOPMENT ACROSS PORTIONS OF
CENTRAL/SOUTHERN IA THROUGH THE 00Z-03Z TIMEFRAME.

..GUYER.. 07/24/2009

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

ATTN...WFO...DMX...EAX...OAX...

LAT...LON   41939577 42539470 42699251 40679285 40439518 41939577

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 24, 9:51 AM CDT	Mesoscale Discussion	SPC	Allamakee, Black Hawk, Bremer, Buchanan, Butler, Cerro Gordo and 11 more	54 min
Jul 24, 10:32 AM CDT	Severe Thunderstorm Watch	SPC	Allamakee, Benton, Black Hawk, Boone, Bremer, Buchanan and 35 more	6 hr
Jul 24, 1:12 PM CDT	Tornado Watch	SPC	Benton, Buchanan, Cedar, Clayton, Clinton, Delaware and 12 more	4 hr
Jul 24, 2:24 PM CDT	Mesoscale Discussion	SPC	Adair, Benton, Black Hawk, Boone, Bremer, Butler and 35 more	96 min
Jul 24, 3:52 PM CDT	Mesoscale Discussion	SPC	Allamakee, Benton, Buchanan, Cedar, Clayton, Clinton and 14 more	83 min
Jul 24, 5:02 PM CDT	Tornado Watch	SPC	Allamakee, Benton, Buchanan, Cedar, Chickasaw, Clayton and 15 more	6 hr

Nearby

Mesoscale Discussions in Iowa, 2009 Every mesoscale discussion in 2009

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.