Alert archive / Iowa / Mesoscale Discussions in 2012

Mesoscale Discussion 402

March 31, 201220 counties in Illinois; 26 counties in Iowa

The Storm Prediction Center issued this mesoscale discussion at Mar 31, 2012, 8:52 PM CDT for 20 counties in Illinois; 26 counties in Iowa. It was in force for 53 min.

The area

The outline as issued.

The facts

Issued: Mar 31, 2012, 8:52 PM CDT (01:52 UTC)
Expired: Mar 31, 2012, 9:45 PM CDT
In force: 53 min
Issued by: the Storm Prediction Center

All 46 counties

Benton County, IA, Black Hawk County, IA, Buchanan County, IA, Cedar County, IA, Clinton County, IA, Delaware County, IA, Des Moines County, IA, Dubuque County, IA, Grundy County, IA, Henry County, IA, Iowa County, IA, Jackson County, IA, Jasper County, IA, Jefferson County, IA, Johnson County, IA, Jones County, IA, Keokuk County, IA, Linn County, IA, Louisa County, IA, Mahaska County, IA, Marshall County, IA, Muscatine County, IA, Poweshiek County, IA, Scott County, IA, Tama County, IA, Washington County, IA, Bureau County, IL, Carroll County, IL, DeKalb County, IL, Henderson County, IL, Henry County, IL, Jo Daviess County, IL, Kendall County, IL, Knox County, IL, LaSalle County, IL, Lee County, IL, Marshall County, IL, Mercer County, IL, Ogle County, IL, Peoria County, IL, Putnam County, IL, Rock Island County, IL, Stark County, IL, Stephenson County, IL, Warren County, IL, Whiteside County, IL

The radar

The Quad Cities radar (KDVN), 47 km from the middle of the area, began a volume at 01:54 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 124Mar 31, 9:25 PM CDT

The nearest sounding before it

Davenport, (KDVN), launched 00:00Z, 1.9 hours before the alert went out and 54 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 1520 m above ground
0-6 km bulk shear: 41 kt
0-1 km storm-relative helicity: 196 m²/s²
0-3 km storm-relative helicity: 306 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.3

Open this sounding in Storm Lab

The text

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

190 
ACUS11 KWNS 010153
SWOMCD
SPC MCD 010152
ILZ000-IAZ000-WIZ000-010245-

MESOSCALE DISCUSSION 0402
NWS STORM PREDICTION CENTER NORMAN OK
0852 PM CDT SAT MAR 31 2012

AREAS AFFECTED...CNTRL/ERN IA...NWRN IL

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 010152Z - 010245Z

AN INCREASE IN TSTM COVERAGE IS ANTICIPATED THROUGH THE LATE EVENING
HRS FROM CNTRL IA EWD INTO NWRN IL...WITH A PRIMARY THREAT FOR LARGE
HAIL. CONSIDERABLE UNCERTAINTY SURROUNDING SPECIFIC TIMING/MAGNITUDE
OF SVR POTENTIAL EXISTS...BUT CONVECTIVE TRENDS ARE BEING MONITORED
FOR A POSSIBLE WW...PERHAPS AS SOON AS THE NEXT 1-2 HRS.

SFC ANALYSIS FROM 01Z PLACES A WARM FRONT FROM 30 SSE OTM TO 10 NNW
SUX. TO THE NE OF THE WARM FRONT...RADAR ECHOES HAVE DEVELOPED
APPROXIMATELY 40 W OF CEDAR RAPIDS...WITH A NARROW WAA REGIME AIDED
BY A 30-40 KT SWLY LLJ /PER DMX VWP/. WITH TIME...A GRADUAL
INTENSIFICATION/EWD EXPANSION OF TSTMS IS EXPECTED. STEEP MIDLEVEL
LAPSE RATES /SAMPLED AT 7-8 C/KM PER DVN 00Z SOUNDING/ AND MUCAPE
VALUES EXCEEDING 1000 J/KG...ALONG WITH MODERATE W-NWLY MIDLEVEL
FLOW...WILL SUPPORT ELEVATED TSTMS /SOME SUPERCELLS/ CAPABLE OF
PRODUCING LARGE HAIL AS THE PRIMARY THREAT. A MAJORITY OF AVAILABLE
HIGH-RESOLUTION CONVECTION ALLOWING GUIDANCE /INCLUDING 23Z WRF-HRRR
AND 12Z WRF-NMM/ APPEARS TO BE TOO SLOW/FAR EAST WITH INITIAL
CONVECTIVE DEVELOPMENT...BUT GENERAL TREND IS FOR A GRADUAL EWD
EXPANSION OF TSTMS INTO ERN IA AND EVENTUALLY NRN IL AS LOW-LEVEL
WAA BECOMES FOCUSED FARTHER E. CONSIDERABLE UNCERTAINTY SURROUNDING
EVOLUTION OF CONVECTION AND TIMING OF ASSOCIATED LARGE HAIL THREAT
REMAINS...BUT THE AREA IS BEING MONITORED FOR A POSSIBLE WW.

..ROGERS.. 04/01/2012

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

ATTN...WFO...LOT...ILX...DVN...ARX...DMX...

LAT...LON   41079247 41599338 42169345 42619257 42509041 42248910
            41508832 40988862 40718988 40809189 41079247

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Mar 31, 9:24 PM CDT	Severe Thunderstorm Watch	SPC	Boone, Bureau, Carroll, DeKalb, Henry, Jo Daviess and 16 more	9 hr
Apr 1, 1:33 AM CDT	Mesoscale Discussion	SPC	Boone, Bureau, Carroll, DeKalb, Fulton, Grundy and 21 more	117 min
Apr 1, 7:56 AM CDT	Mesoscale Discussion	SPC	Boone, Bureau, Carroll, DeKalb, Fulton, Grundy and 21 more	2 hr

Nearby

Mesoscale Discussions in Iowa, 2012 Mesoscale Discussions in Illinois, 2012 Every 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.