Mesoscale Discussion 1885

Issued

Sep 4, 2012, 8:30 PM CDT (01:30 UTC)

Expired

Sep 4, 2012, 9:30 PM CDT

In force

60 min

Issued by

the Storm Prediction Center

The La Crosse radar (KARX), 142 km from the middle of the area, began a volume at 01:29 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.

• Severe Thunderstorm Watch 616Sep 4, 8:50 PM CDT
• Severe Thunderstorm Watch 618Sep 4, 11:15 PM CDT

362 
ACUS11 KWNS 050131
SWOMCD
SPC MCD 050130
WIZ000-MIZ000-ILZ000-MNZ000-IAZ000-050230-

MESOSCALE DISCUSSION 1885
NWS STORM PREDICTION CENTER NORMAN OK
0830 PM CDT TUE SEP 04 2012

AREAS AFFECTED...CNTRL/E-CNTRL WI...NERN IA...FAR WRN UP OF MI...FAR
NRN IL

CONCERNING...SEVERE THUNDERSTORM WATCH 614...

VALID 050130Z - 050230Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 614
CONTINUES.

SUMMARY...LOCAL EXTENSION OF THE WW WILL LIKELY BE REQUIRED AS TSTM
ACTIVITY CONTINUES TO PROGRESS EWD AND MOVES OUT OF THE CURRENT
WATCH AREA. TSTM ACTIVITY SHOULD CONTINUE FOR ANOTHER HOUR OR TWO
BEFORE BEGINNING A WEAKENING TREND.

DISCUSSION...TSTM ACTIVITY ACROSS THE WATCH AREA HAS EVOLVED INTO
THREE SEPARATE LINE SEGMENTS. THE FIRST IS MOVING EWD ACROSS LAKE
SUPERIOR AND ONTO THE WRN COAST OF MICHIGAN/S UPPER PENINSULA. THIS
ACTIVITY HAS SHOWN SOME INTENSIFICATION DURING THE PAST HOUR BUT A
DIMINISHING TREND IS ANTICIPATED AS THE BOUNDARY LAYER CONTINUES TO
COOL. THE SECOND IS ACROSS CNTRL WI AND HAS EXHIBITED AN INCREASE IN
FORWARD-PROPAGATION DURING THE LAST HOUR. LATEST KGRB RADAR IMAGERY
SHOWS THE OUTFLOW IS BEGINNING TO PUSH AHEAD OF THE LINE AND A
WEAKENING TREND IS EXPECTED DURING THE NEXT HOUR WITH THIS LINE OF
STORMS AS WELL. THE THIRD IS MOVING SWD ACROSS SRN WI INTO FAR NWRN
IA AND POSSIBLY NRN IL. THIS SEGMENT EVOLVED FROM A CLUSTER OF
SUPERCELLS AROUND AND SE OF LSE AND THE ARX VAD WIND PROFILE SHOWS A
DECENT REAR INFLOW JET SIGNATURE. THIS SIGNATURE HAS BEEN GRADUALLY
WEAKENING AS THE LINE MOVES FARTHER S. THE MATURE NATURE OF THIS
LINE MAY ALLOW IT TO CONTINUE FOR LONGER THAN THE OTHER TWO LINES
PREVIOUSLY MENTIONED...BUT IT TOO WILL ENCOUNTER AN INCREASINGLY
MORE STABLE ENVIRONMENT AS THE BOUNDARY LAYER COOLS/DECOUPLES. THE
ERN PORTION OF THE LINE /NEARING MKE/...HAS RECENTLY ACCELERATED EWD
AS THE OUTFLOW PUSHES SEWD. THIS SEEMS TO SIGNAL THAT THIS PORTION
OF THE STORM WILL BEGIN WEAKENING SHORTLY BUT IT MAY REMAIN CAPABLE
OF PRODUCING A FEW SVR GUSTS IN NRN IL. A DOWNSTREAM WW MAY BE NEED
ACROSS THIS AREA.

..MOSIER.. 09/05/2012

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

ATTN...WFO...MQT...GRB...LOT...MKX...DVN...DLH...ARX...MPX...
DMX...

LAT...LON   48189180 48049140 48239087 48099067 48018978 47968860
            47238861 47028898 45488907 45478946 45168943 45098921
            45038922 45048899 44958899 44958876 44668778 44338775
            44248804 43918805 43988958 43648959 43658894 43638841
            43218843 43198853 42848854 42838831 42488830 42358830
            42378896 42378991 42218989 42199024 42209298 43219301
            43219254 43529253 43519175 43849173 43859133 44119114
            44609114 44599090 45399094 45389066 45649064 45649152
            46769154 47169178 48189180

Mesoscale Discussions in Wisconsin, 2012Mesoscale Discussions in Iowa, 2012Mesoscale Discussions in Minnesota, 2012Every mesoscale discussion in 2012

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.