Alert archive / Wisconsin / Mesoscale Discussions in 2016

Mesoscale Discussion 1561

August 18, 20164 counties in Illinois; 9 counties in Iowa; 16 counties in Wisconsin

The Storm Prediction Center issued this mesoscale discussion at Aug 18, 2016, 7:41 PM CDT for 4 counties in Illinois; 9 counties in Iowa; 16 counties in Wisconsin. It was in force for 94 min.

The area

The outline as issued.

The facts

Issued
Aug 18, 2016, 7:41 PM CDT (00:41 UTC)
Expired
Aug 18, 2016, 9:15 PM CDT
In force
94 min
Issued by
the Storm Prediction Center
All 29 counties

Allamakee County, IA, Bremer County, IA, Buchanan County, IA, Chickasaw County, IA, Clayton County, IA, Delaware County, IA, Dubuque County, IA, Fayette County, IA, Jackson County, IA, Carroll County, IL, Jo Daviess County, IL, Stephenson County, IL, Winnebago County, IL, Adams County, WI, Columbia County, WI, Crawford County, WI, Dane County, WI, Grant County, WI, Green County, WI, Iowa County, WI, Juneau County, WI, La Crosse County, WI, Lafayette County, WI, Marquette County, WI, Monroe County, WI, Richland County, WI, Rock County, WI, Sauk County, WI, Vernon County, WI

The radar

The La Crosse radar (KARX), 93 km from the middle of the area, began a volume at 00:44 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, 0.7 hours before the alert went out and 160 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-pSkew-T log-p diagram, Davenport, at 00:00Z on 2016-08-19Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 2258 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Davenport, at 00:00Z on 2016-08-19The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 40 square meters per square second.1939Sfc1 km3 km6 km9 kmRMLM
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
2258 J/kg
Mixed-layer CIN
-48 J/kg
Mixed-layer LCL
1216 m above ground
0-6 km bulk shear
15 kt
0-1 km storm-relative helicity
40 m²/s²
0-3 km storm-relative helicity
138 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

607 
ACUS11 KWNS 190041
SWOMCD
SPC MCD 190041 
WIZ000-ILZ000-IAZ000-190215-

MESOSCALE DISCUSSION 1561
NWS STORM PREDICTION CENTER NORMAN OK
0741 PM CDT THU AUG 18 2016

AREAS AFFECTED...SRN WI...NERN IA...NWRN IL

CONCERNING...SEVERE THUNDERSTORM WATCH 450...451...

VALID 190041Z - 190215Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH
450...451...CONTINUES.

SUMMARY...AN ISOLATED DAMAGING WIND RISK CONTINUES WITH THE
CONVECTIVE SYSTEM MOVING INTO SOUTHERN WI/NORTHEAST IA. OTHER
ISOLATED STORMS ACROSS NORTHWEST IL WILL BE CAPABLE OF LOCALLY
SEVERE HAIL. ADDITIONAL WATCH ISSUANCE BEYOND THE CONFINES OF WW
450/451 IS NOT ANTICIPATED.

DISCUSSION...AT 0030Z...A BOWING THUNDERSTORM CLUSTER CONTINUES
MOVING ESEWD ACROSS NERN IA/SWRN WI. SOME WEAKENING HAS BEEN
NOTED...LIKELY DUE TO INCREASINGLY WEAK VERTICAL SHEAR /AS NOTED IN
00Z DVN SOUNDING/ AND THE ONSET OF DIURNAL BOUNDARY-LAYER
DESTABILIZATION. HOWEVER...A LOCAL DAMAGING WIND RISK WILL CONTINUE
FOR ANOTHER 1-2 HOURS IN AREAS ALONG THE LEADING EDGE OF THE COLD
POOL WHERE VIGOROUS CONVECTION REMAINS. 

AN ADDITIONAL STRONG ISOLATED STORM HAS DEVELOPED ACROSS NWRN IL.
WEAK VERTICAL SHEAR SHOULD LIMIT THE LONGEVITY OF THIS STORM...BUT A
LOCALIZED HAIL AND DOWNBURST RISK WILL EXIST WITH THIS STORM AND ANY
OTHER CELLS THAT DEVELOP AHEAD OF THE MAIN CONVECTIVE SYSTEM...GIVEN
STRONG BUOYANCY THAT IS IN PLACE. IN ADDITION...THE WEAKENING
CONVECTIVE SYSTEM TO THE NORTH WILL MOVE INTO PORTIONS OF ERN
IA/NWRN IL SOUTH OF WW 450/451 BETWEEN 01-02Z...WITH SOME POTENTIAL
FOR LOCALLY STRONG WIND GUSTS. HOWEVER...ADDITIONAL WATCH ISSUANCE
IS NOT CURRENTLY ANTICIPATED GIVEN THE INCREASINGLY MARGINAL NATURE
OF THE THREAT.

..DEAN/GRAMS.. 08/19/2016

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

ATTN...WFO...GRB...LOT...MKX...DVN...ARX...DMX...

LAT...LON   43009276 43369162 43479113 44019125 44119067 44198982
            43888932 43028895 42498902 42168916 41918964 42019045
            42409213 42659268 43009276

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 18, 7:23 PM CDTSevere Thunderstorm WatchSPCLyon, Osceola4 hr
Aug 18, 9:36 PM CDTMesoscale DiscussionSPCDickinson, Lyon, Osceola84 min

Nearby

Mesoscale Discussions in Wisconsin, 2016Mesoscale Discussions in Iowa, 2016Mesoscale Discussions in Illinois, 2016Every mesoscale discussion in 2016

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.