Alert archive / Kansas / Mesoscale Discussions in 2012

Mesoscale Discussion 1874

September 3, 201213 counties in Kansas

The Storm Prediction Center issued this mesoscale discussion at Sep 3, 2012, 5:13 PM CDT for 13 counties in Kansas. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Sep 3, 2012, 5:13 PM CDT (22:13 UTC)
Expired: Sep 3, 2012, 7:15 PM CDT
In force: 2 hr
Issued by: the Storm Prediction Center
Chance of a watch: 20%

Counties Allen County, KS, Anderson County, KS, Chautauqua County, KS, Coffey County, KS, Elk County, KS, Greenwood County, KS, Labette County, KS, Lyon County, KS, Montgomery County, KS, Neosho County, KS, Osage County, KS, Wilson County, KS, Woodson County, KS

The radar

The Topeka radar (KTWX), 141 km from the middle of the area, began a volume at 22:14 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

Topeka, KS (KTOP), launched 12:00Z, 10.2 hours before the alert went out and 133 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 685 J/kg
Mixed-layer CIN: -331 J/kg
Mixed-layer LCL: 1411 m above ground
0-6 km bulk shear: 16 kt
0-1 km storm-relative helicity: 60 m²/s²
0-3 km storm-relative helicity: 159 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.3

Open this sounding in Storm Lab

The text

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

661 
ACUS11 KWNS 032213
SWOMCD
SPC MCD 032213 
OKZ000-KSZ000-040015-

MESOSCALE DISCUSSION 1874
NWS STORM PREDICTION CENTER NORMAN OK
0513 PM CDT MON SEP 03 2012

AREAS AFFECTED...PART OF ERN KS THROUGH EXTREME NERN OK

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

VALID 032213Z - 040015Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...WIDELY SCATTERED SHOWERS AND THUNDERSTORMS MIGHT BECOME
CAPABLE OF PRODUCING A FEW DOWNBURSTS OVER A PORTION OF ERN KS AND
EXTREME NERN OK THROUGH EARLY EVENING. COVERAGE OF ANY SEVERE EVENTS
IS EXPECTED TO REMAIN SPARSE...AND A WW IS NOT ANTICIPATED.

DISCUSSION...EARLY THIS EVENING THE BOUNDARY LAYER OVER SERN KS HAS
MIXED OUT TO THE SOUTH OF A QUASISTATIONARY FRONT WHERE TEMPERATURES
HAVE WARMED INTO THE LOW 100S AND DEWPOINTS HAVE DROPPED INTO THE
50S. WARM AIR ALOFT /-7C AT 500 MB/ AND MODEST LOW LEVEL MOISTURE
YIELD MARGINAL INSTABILITY WITH MLCAPE AOB 800 J/KG WHICH SHOULD
LIMIT DEGREE OF PRECIPITATION LOADING IN UPDRAFTS.
NEVERTHELESS...STEEP LOW LEVEL LAPSE RATES WITHIN THE DEEPLY MIXED
BOUNDARY LAYERS WILL PROMOTE A THREAT OF ISOLATED WIND DAMAGE WITH
DEVELOPING CONVECTION. 

THE ATMOSPHERE IS MORE UNSTABLE ALONG AND EAST OF THE BOUNDARY
ACROSS EXTREME ERN KS INTO WRN MO...BUT LACK OF CUMULUS DEVELOPMENT
SUGGESTS THE BOUNDARY LAYER IS CAPPED WHICH IS ALSO REFLECTED ON
PFCS FROM THE RAPID REFRESH MODEL. THUS STORMS WILL PROBABLY WEAKEN
AS THEY ATTEMPT TO MOVE FARTHER EAST INTO THE AXIS OF STRONGER
INSTABILITY...ESPECIALLY GIVEN APPARENT WEAK MESOSCALE FORCING.

..DIAL/MEAD.. 09/03/2012

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

ATTN...WFO...SGF...TSA...TOP...ICT...

LAT...LON   37709491 36919493 36829605 37499646 38359651 38809635
            38649554 37709491

Nearby

Mesoscale Discussions in Kansas, 2012 Every 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.