Alert archive / Minnesota / Mesoscale Discussions in 2012

Mesoscale Discussion 832

May 18, 201223 counties in Minnesota

The Storm Prediction Center issued this mesoscale discussion at May 18, 2012, 4:54 PM CDT for 23 counties in Minnesota. It was in force for 66 min.

The area

The outline as issued.

The facts

Issued
May 18, 2012, 4:54 PM CDT (21:54 UTC)
Expired
May 18, 2012, 6:00 PM CDT
In force
66 min
Issued by
the Storm Prediction Center
Chance of a watch
20%
All 23 counties

Anoka County, MN, Benton County, MN, Blue Earth County, MN, Brown County, MN, Carver County, MN, Faribault County, MN, Hennepin County, MN, Isanti County, MN, Kanabec County, MN, Le Sueur County, MN, Martin County, MN, McLeod County, MN, Meeker County, MN, Mille Lacs County, MN, Morrison County, MN, Nicollet County, MN, Scott County, MN, Sherburne County, MN, Sibley County, MN, Stearns County, MN, Waseca County, MN, Watonwan County, MN, Wright County, MN

The radar

The Minneapolis radar (KMPX), 49 km from the middle of the area, began a volume at 21:56 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

Minneapolis, MN (KMPX), launched 12:00Z, 9.9 hours before the alert went out and 47 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, Minneapolis, MN at 12:00Z on 2012-05-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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, Minneapolis, MN at 12:00Z on 2012-05-18The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 154 square meters per square second.19395878Sfc1 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
1992 m above ground
0-6 km bulk shear
14 kt
0-1 km storm-relative helicity
154 m²/s²
0-3 km storm-relative helicity
274 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.4

Open this sounding in Storm Lab

The text

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

046 
ACUS11 KWNS 182154
SWOMCD
SPC MCD 182154 
MNZ000-IAZ000-182300-

MESOSCALE DISCUSSION 0832
NWS STORM PREDICTION CENTER NORMAN OK
0454 PM CDT FRI MAY 18 2012

AREAS AFFECTED...CNTRL / SRN MN

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

VALID 182154Z - 182300Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...STRONG TSTMS CAPABLE OF LOCALLY ENHANCED WIND GUSTS
APPROACHING SEVERE LEVELS WILL BE POSSIBLE INTO MID-EVENING.  A
WATCH IS NOT ANTICIPATED OWING TO THE MARGINAL NATURE OF THE THREAT.

DISCUSSION...A N-S BAND OF TSTMS HAS RECENTLY DEVELOPED FROM NEAR
STC SWD TO JUST N OF FRM...APPARENTLY IN ASSOCIATION WITH A WEAK
MIDLEVEL VORTICITY MAXIMUM TRANSLATING NEWD THROUGH THE MID-MO
VALLEY.  AMBIENT AIR MASS IS CHARACTERIZED BY A HOT AND DEEPLY MIXED
BOUNDARY LAYER WHERE T-TD SPREADS ARE APPROACHING 50 F.  WHILE
VERTICAL SHEAR WILL REMAIN SUB-OPTIMAL FOR STORM ORGANIZATION AND
SUSTENANCE...THE PRESENCE OF STEEP LOW TO MIDLEVEL LAPSE RATES AND
DCAPE VALUES AROUND 1500 J/KG MAY PROMOTE STRONG EVAPORATIVE COOLING
POTENTIAL WITH RESULTANT SURFACE WIND GUSTS APPROACHING SEVERE
LEVELS.

..MEAD.. 05/18/2012

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

ATTN...WFO...DLH...MPX...DMX...FSD...

LAT...LON   43599508 45199480 46019458 46329423 46339337 45699304
            44559322 43759366 43579418 43489462 43599508

Nearby

Mesoscale Discussions in Minnesota, 2012Every mesoscale discussion in 2012

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.