Mesoscale Discussion 1582

Issued

Jul 25, 2012, 5:24 AM CDT (10:24 UTC)

Expired

Jul 25, 2012, 6:30 AM CDT

In force

66 min

Issued by

the Storm Prediction Center

The Duluth radar (KDLH), 79 km from the middle of the area, began a volume at 10:25 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.

528 
ACUS11 KWNS 251024
SWOMCD
SPC MCD 251024 
MIZ000-WIZ000-MNZ000-SDZ000-NDZ000-251130-

MESOSCALE DISCUSSION 1582
NWS STORM PREDICTION CENTER NORMAN OK
0524 AM CDT WED JUL 25 2012

AREAS AFFECTED...PARTS OF CENTRAL AND NORTHEAST MN INTO NWRN/NRN WI
AND WRN UPPER MI

CONCERNING...SEVERE THUNDERSTORM WATCH 517...

VALID 251024Z - 251130Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 517
CONTINUES.

SUMMARY...AN ISOLATED THREAT FOR STRONG TO SEVERE STORMS REMAINS
ACROSS WW 517...WHILE THE OVERALL THREAT COVERAGE THAT WARRANTED THE
ISSUANCE OF THIS WATCH APPEARS TO HAVE UNDERGONE SUBSTANTIAL
WEAKENING.  IF DIMINISHING TRENDS CONTINUE...THEN THIS WATCH MAY BE
CANCELLED PRIOR TO 13Z.

DISCUSSION...TRENDS IN RADAR AND SATELLITE IMAGERY DURING THE LAST
1-2 HOURS INDICATED A LARGE MCS MOVING EWD ACROSS CENTRAL AND NERN
MN INTO FAR NWRN WI AND WRN LAKE SUPERIOR.  AN APPARENT MCV AND/OR
MIDLEVEL IMPULSE ATTENDANT TO THIS SYSTEM WAS LOCATED IN NERN MN
WITH THE LEADING BAND OF TSTMS TRAILING SWD THROUGH SRN LAKE COUNTY
MN TO DOUGLAS COUNTY WI AND THEN SWWD ACROSS MUCH OF CENTRAL MN. 
STRONG LOW LEVEL WAA LOCATED WITHIN THE EXIT REGION OF A 40-45 KT
SWLY LLJ EXTENDING INTO EAST CENTRAL/NERN MN AND NWRN WI TO WRN
UPPER MS WILL MAINTAIN ONGOING FORWARD PROPAGATING MCS THIS MORNING.
 ALTHOUGH BULK SHEAR OF 35-50 KT REMAINS SUFFICIENT FOR ORGANIZED
STORMS...A FAIRLY SUBSTANTIAL REDUCTION IN AVAILABLE INSTABILITY
WILL TEND TO LIMIT THE OVERALL SEVERE WEATHER THREAT.

FARTHER W...ASCENT OVER NERN SD WITHIN THE EXIT REGION OF A 40-50 KT
SWLY MIDLEVEL JET ATTENDANT TO AN IMPULSE MOVING NEWD THROUGH
CENTRAL SD WILL SUPPORT ADDITIONAL CONVECTION/TSTMS FROM NERN SD
INTO WEST CENTRAL MN.  ALTHOUGH BULK SHEAR OF 40-50 KT IS SUPPORTIVE
OF ORGANIZED STORMS...THE FACT THAT ONGOING ACTIVITY IS MOVING INTO
A REGION OF WEAKER INSTABILITY SUGGESTS THE POTENTIAL FOR ADDITIONAL
STRONGER/SUSTAINED UPDRAFTS SHOULD BE LOW.

MEANWHILE...RADAR IMAGERY AND LIGHTNING DATA ALSO SHOWED TWO BANDS
OF STORMS EXTENDING NNW-SSE FROM NRN-SRN WI AND FAR NERN IL.  THIS
ACTIVITY APPEARS TO BE LOCATED PARALLEL TO A COUPLE OF 850 MB
THERMAL GRADIENTS AND IS BEING SUPPORTED BY LOW LEVEL WAA...THE ERN
EXTENT OF A STEEP MIDLEVEL LAPSE RATE PLUME.  MODEST EFFECTIVE BULK
SHEAR /20-30 KT/ AND WEAK INSTABILITY SHOULD LIMIT THE SEVERE
WEATHER THREAT AS THIS ACTIVITY PROGRESSES EWD THIS MORNING.

..PETERS.. 07/25/2012

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

ATTN...WFO...MQT...GRB...MKX...DLH...ARX...MPX...FGF...ABR...

LAT...LON   45269367 45279612 45229761 45899819 46369575 46839469
            47449454 47829430 47959317 48659300 48089149 48209089
            47898963 46938961 46658910 45328878 44328847 43218849
            43578922 45438964 45209183 45309297 45419352 45269367

Mesoscale Discussions in Minnesota, 2012Mesoscale Discussions in Wisconsin, 2012Mesoscale Discussions in South Dakota, 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.