Alert archive / Wisconsin / Mesoscale Discussions in 2013

Mesoscale Discussion 1925

October 3, 2013Boone County, McHenry County, Illinois; 11 counties in Wisconsin

The Storm Prediction Center issued this mesoscale discussion at Oct 3, 2013, 9:15 PM CDT for Boone County, McHenry County, Illinois; 11 counties in Wisconsin. It was in force for 90 min.

The area

The outline as issued.

The facts

Issued
Oct 3, 2013, 9:15 PM CDT (02:15 UTC)
Expired
Oct 3, 2013, 10:45 PM CDT
In force
90 min
Issued by
the Storm Prediction Center
Chance of a watch
20%

Counties Boone County, IL, McHenry County, IL, Dane County, WI, Dodge County, WI, Jefferson County, WI, Kenosha County, WI, Milwaukee County, WI, Ozaukee County, WI, Racine County, WI, Rock County, WI, Walworth County, WI, Washington County, WI, Waukesha County, WI

The radar

The Milwaukee radar (KMKX), 19 km from the middle of the area, began a volume at 02:16 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, 2.3 hours before the alert went out and 237 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 2013-10-04Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1514 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 2013-10-04The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 148 square meters per square second.193958Sfc1 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
1514 J/kg
Mixed-layer CIN
-10 J/kg
Mixed-layer LCL
921 m above ground
0-6 km bulk shear
27 kt
0-1 km storm-relative helicity
148 m²/s²
0-3 km storm-relative helicity
196 m²/s²
Significant tornado parameter
0.7
Supercell composite
4.0

Open this sounding in Storm Lab

The text

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

834 
ACUS11 KWNS 040216
SWOMCD
SPC MCD 040215 
WIZ000-ILZ000-040345-

MESOSCALE DISCUSSION 1925
NWS STORM PREDICTION CENTER NORMAN OK
0915 PM CDT THU OCT 03 2013

AREAS AFFECTED...SE WI...FAR NE IL...LAKE MI

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

VALID 040215Z - 040345Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...AN ISOLATED SEVERE THREAT APPEARS LIKELY TO CONTINUE FOR A
FEW MORE HOURS ACROSS SE WI AND MOVE EWD INTO LAKE MI LATE THIS
EVENING. WIND DAMAGE AND HAIL WILL BE THE PRIMARY THREATS BUT A
BRIEF TORNADO CAN NOT BE RULED OUT.

DISCUSSION...THE LATEST SFC ANALYSIS SHOWS A QUASI-STATIONARY FRONT
EXTENDING EWD ACROSS NE IA INTO SRN WI. THUNDERSTORMS ARE ONGOING
ALONG AND TO THE NORTH OF THE FRONT. SFC DEWPOINTS IN THE VICINITY
OF THE FRONT ARE IN THE MID 60S F AND MLCAPE IS ESTIMATED AROUND
1000 J/KG. THIS COMBINED WITH 35 TO 40 KT OF 0-6 KM SHEAR SHOULD BE
SUFFICIENT FOR AN ISOLATED SEVERE THREAT. IN ADDITION...THE WSR-88D
VWP AT MILWAUKEE SHOWS DIRECTIONAL SHEAR IN THE BOUNDARY LAYER WITH
0-1 KM SHEAR AT 30 KT. THIS MAY BE ENOUGH FOR A BRIEF TORNADO WITH
CELLS THAT CAN OBTAIN ROTATION. ISOLATED DAMAGING WIND GUSTS AND
HAIL WILL ALSO BE POSSIBLE WITH THE STRONGER CELLS. THE SEVERE
THREAT OVER LAND MAY LESSEN AS THE CELLS MOVE OVER LAKE MI LATE THIS
EVENING.

..BROYLES/CORFIDI.. 10/04/2013

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

ATTN...WFO...LOT...MKX...

LAT...LON   43708764 43688862 43398914 43048946 42438929 42268865
            42318790 42458747 43288743 43708764

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Oct 4, 4:35 AM CDTMesoscale DiscussionSPCCarroll, Jo Daviess85 min
Oct 4, 9:03 AM CDTMesoscale DiscussionSPCBureau, Henderson, Henry, Knox, Mercer, Putnam and 4 more87 min

Nearby

Mesoscale Discussions in Wisconsin, 2013Mesoscale Discussions in Illinois, 2013Every mesoscale discussion in 2013

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.