Mesoscale Discussion 1213

Issued

Jun 18, 2012, 9:11 PM CDT (02:11 UTC)

Expired

Jun 18, 2012, 10:45 PM CDT

In force

94 min

Issued by

the Storm Prediction Center

Chance of a watch

60%

The Sioux Falls radar (KFSD), 48 km from the middle of the area, began a volume at 02:12 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 408Jun 18, 10:10 PM CDT

418 
ACUS11 KWNS 190212
SWOMCD
SPC MCD 190211
MNZ000-IAZ000-SDZ000-190345-

MESOSCALE DISCUSSION 1213
NWS STORM PREDICTION CENTER NORMAN OK
0911 PM CDT MON JUN 18 2012

AREAS AFFECTED...PARTS OF SRN/ERN SOUTH DAKOTA INTO SRN MINNESOTA

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 190211Z - 190345Z

PROBABILITY OF WATCH ISSUANCE...60 PERCENT

SUMMARY...UNCERTAINTY LINGERS CONCERNING THE INITIATION OF STORM
DEVELOPMENT THIS EVENING.  BUT ONCE IT BECOMES MORE CERTAIN...A WW
WILL PROBABLY BE NEEDED.

DISCUSSION...A PLUME OF VERY WARM ELEVATED MIXED LAYER AIR...WHICH
HAS ADVECTED OFF THE PLATEAU REGION THROUGH MUCH OF THE SOUTHERN AND
CENTRAL PLAINS AND MIDDLE MISSOURI VALLEY REGION...CONTINUES TO
PROVIDE STRONG INHIBITION TO CONVECTIVE DEVELOPMENT SOUTH OF THE
SOUTHERN SOUTH DAKOTA AND SOUTHERN MINNESOTA STATE BORDERS.  THE
LOWER AND MID-LEVEL THERMAL GRADIENT IS SHARP ALONG THE NORTHERN
PERIPHERY OF THIS PLUME...WHERE CONVERGENCE AND WARM ADVECTION ARE
EXPECTED TO STRENGTHEN SUBSTANTIALLY THROUGH THE 03-06Z TIME FRAME.
GUIDANCE CONTINUES TO INDICATE THAT THIS WILL OCCUR WITH SOUTH
SOUTHWESTERLY 850 MB JET STRENGTHENING IN EXCESS OF 50 KT ACROSS THE
CENTRAL PLAINS.

THE ENVIRONMENT REMAINS RELATIVELY DRY ACROSS MUCH OF THE DAKOTAS
AND MINNESOTA...BUT HIGH MOISTURE CONTENT AIR IS PRESENT ALONG AND
SOUTH OF A REMNANT CONVECTIVELY GENERATED OR ENHANCED BOUNDARY
EXTENDING ACROSS SOUTHERN MINNESOTA AND NORTHWEST IOWA INTO NORTHERN
NEBRASKA.  THIS BOUNDARY HAS ALREADY BEGUN TO LIFT NORTHWARD THROUGH
THE MID MISSOURI VALLEY...WITH RAPID SURFACE DEW POINT INCREASES
INTO THE UPPER 60S/NEAR 70F OBSERVED OVER SOUTHEASTERN SOUTH DAKOTA
DURING THE PAST FEW HOURS.

UNCERTAINTY LINGERS CONCERNING LOCATION OF CONVECTIVE INITIATION
THIS EVENING...BUT SOME GUIDANCE HAS BEEN SUGGESTIVE THAT BOUNDARY
LAYER BASED STORM DEVELOPMENT MAY NOT BE OUT OF THE QUESTION BY
03-04Z ACROSS THE YANKTON/SIOUX FALLS AREA.  OTHERWISE...POTENTIAL
FOR VIGOROUS CONVECTION ROOTED ABOVE THE BOUNDARY LAYER APPEARS MORE
LIKELY ACROSS AREAS OF SOUTHEASTERN SOUTH DAKOTA AND SOUTHERN
MINNESOTA...A BIT FARTHER TO THE NORTHEAST.  WITH STEEP MID-LEVEL
LAPSE RATES SUPPORTING SIZABLE CAPE IN THE PRESENCE STRONG SHEAR
BENEATH 50-70 KT WESTERLY 500 MB FLOW...SEVERE STORMS...INCLUDING A
FEW SUPERCELLS APPEAR PROBABLY ONCE ACTIVITY INITIATES.

..KERR/CARBIN.. 06/19/2012

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

ATTN...WFO...MPX...FSD...ABR...

LAT...LON   43399637 43019691 42979808 43449936 44109980 44659869
            45099704 45249569 44879412 44249365 43829383 43399637

Mesoscale Discussions in South Dakota, 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.