Mesoscale Discussion 682

Issued

May 3, 2012, 6:57 PM EDT (22:57 UTC)

Expired

May 3, 2012, 8:00 PM EDT

In force

63 min

Issued by

the Storm Prediction Center

The Grand Rapids radar (KGRR), 66 km from the middle of the area, began a volume at 22:58 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.

437 
ACUS11 KWNS 032257
SWOMCD
SPC MCD 032257 
MIZ000-INZ000-040000-

MESOSCALE DISCUSSION 0682
NWS STORM PREDICTION CENTER NORMAN OK
0557 PM CDT THU MAY 03 2012

AREAS AFFECTED...SRN LOWER MI

CONCERNING...SEVERE THUNDERSTORM WATCH 231...

VALID 032257Z - 040000Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 231
CONTINUES.

SUMMARY...SVR WEATHER THREAT IS EXPECTED TO PERSIST ACROSS THE SRN
HALF OF LOWER MI THROUGH 02-03Z...WITH THE THREAT ALSO SPREADING
INTO THE REST OF SERN LOWER MI INCLUDING THE DTW METRO AREA BY
00-01Z.  LOCAL WFO AREAL EXTENSION WILL BE DONE TO ACCOUNT FOR THE
INCREASE IN AREAL THREAT.  OTHERWISE...A NEW WW OR TEMPORAL
EXTENSION WILL NEED TO BE CONSIDERED PRIOR TO THE 01Z EXPIRATION
TIME OF WW 231.

DISCUSSION...AT 2245Z...REGIONAL RADAR IMAGERY SHOWED THE STRONGEST
BAND OF TSTMS EXTENDING FROM SRN LAKE HURON SWWD THROUGH SRN LOWER
MI FROM SANILAC COUNTY TO CASS COUNTY.  THIS ACTIVITY WAS MOVING
ENEWD AT 25-30 KT.  OBJECTIVE ANALYSES INDICATED SOME WEAKENING OF
THE WARM SECTOR INSTABILITY ACROSS SRN LOWER MI S AND SE OF THE
PRIMARY TSTM BAND...BUT VALUES ARE EXPECTED TO REMAIN MODERATELY
UNSTABLE THROUGH THE EVENING...WITH EFFECTIVE BULK SHEAR OF 25-30
KT.  THIS WILL MAINTAIN A THREAT FOR SEVERE STORMS AS ACTIVITY MOVES
EWD/ENEWD.

MODELS SUGGEST TSTMS WILL PERSIST THROUGH THE EVENING AFFECTING THE
REST OF SRN/SERN LOWER MI.  BULK SHEAR TENDS TO BE WEAKER WITH SWD
EXTENT AND THUS...SERN LOWER MI /INCLUDING THE DETROIT METRO AREA/
MAY BE THE ONLY AREA THAT NEEDS THE LOCAL AREAL EXTENSION. 
MEANWHILE...THE ENEWD MOVEMENT OF THE TSTM BAND INDICATED SERN LOWER
MI SHOULD CONTINUE TO EXPECT A SEVERE WEATHER THREAT BEYOND THE 01Z
EXPIRATION TIME...RESULTING IN A TEMPORAL EXTENSION OF THIS WW.

..PETERS.. 05/03/2012

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

ATTN...WFO...DTX...IWX...GRR...

LAT...LON   44188286 43338239 42738255 41728359 41738599 41678606
            41758680 42378637 42998632 43368649 43458633 43488547
            43508373 43958329 44188286

Mesoscale Discussions in Michigan, 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.