Alert archive / Nebraska / Mesoscale Discussions in 2012

Mesoscale Discussion 1641

July 28, 201211 counties in Kansas; Atchison County, Missouri; 16 counties in Nebraska

The Storm Prediction Center issued this mesoscale discussion at Jul 28, 2012, 9:06 PM CDT for 11 counties in Kansas; Atchison County, Missouri; 16 counties in Nebraska. It was in force for 84 min.

The area

The outline as issued.

The facts

Issued: Jul 28, 2012, 9:06 PM CDT (02:06 UTC)
Expired: Jul 28, 2012, 10:30 PM CDT
In force: 84 min
Issued by: the Storm Prediction Center

All 28 counties

Clay County, KS, Cloud County, KS, Jackson County, KS, Jewell County, KS, Marshall County, KS, Mitchell County, KS, Nemaha County, KS, Pottawatomie County, KS, Republic County, KS, Riley County, KS, Washington County, KS, Atchison County, MO, Clay County, NE, Fillmore County, NE, Gage County, NE, Hamilton County, NE, Jefferson County, NE, Johnson County, NE, Lancaster County, NE, Nemaha County, NE, Nuckolls County, NE, Otoe County, NE, Pawnee County, NE, Richardson County, NE, Saline County, NE, Seward County, NE, Thayer County, NE, York County, NE

The radar

The Grand Island radar (KUEX), 95 km from the middle of the area, began a volume at 02:08 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

Omaha, NE (KOAX), launched 00:00Z, 2.1 hours before the alert went out and 184 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: 346 J/kg
Mixed-layer CIN: -398 J/kg
Mixed-layer LCL: 1835 m above ground
0-6 km bulk shear: 48 kt
0-1 km storm-relative helicity: 234 m²/s²
0-3 km storm-relative helicity: 475 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 1.1

Open this sounding in Storm Lab

The text

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

514 
ACUS11 KWNS 290206
SWOMCD
SPC MCD 290206 
MOZ000-NEZ000-KSZ000-IAZ000-290330-

MESOSCALE DISCUSSION 1641
NWS STORM PREDICTION CENTER NORMAN OK
0906 PM CDT SAT JUL 28 2012

AREAS AFFECTED...SOUTHEAST NEB/NORTHEAST KS TO IA/MO

CONCERNING...SEVERE THUNDERSTORM WATCH 537...

VALID 290206Z - 290330Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 537
CONTINUES.

SUMMARY...ISOLATED DAMAGING WIND THREAT CONTINUES IN THE
SHORT-TERM...MAINLY ACROSS PORTIONS OF NORTHERN KS THROUGH
MID/PERHAPS LATE EVENING. OTHERWISE...SOME SEVERE HAIL CANNOT BE
RULED OUT...ALTHOUGH THE OVERALL SEVERE THREAT SHOULD REMAIN LIMITED
TONIGHT.

DISCUSSION...SCATTERED ONGOING STORMS ACROSS NORTHERN KS COULD POSE
A DAMAGING WIND THREAT YET THIS EVENING NEAR A FRONTAL ZONE THAT
GENERALLY ANGLES NORTHWEST-SOUTHEAST ACROSS NORTHERN/EASTERN KS.
WHILE THE BOUNDARY LAYER HAS BEGUN TO COOL...RESIDUAL STEEP LOW-MID
LEVEL LAPSE RATES...ALONG WITH LIKELY STORM PERSISTENCE/SOME
ADDITIONAL CELL MERGERS...MAY CONTINUE TO ACCOUNT FOR A CONTINUED
POSSIBILITY FOR DOWNBURSTS/LOCALIZED WIND DAMAGE OVER THE NEXT HOUR
OR TWO. A DEGREE OF UPSCALE GROWTH CANNOT BE COMPLETELY DISCOUNTED
ACROSS NORTHEAST KS WITH AID OF A NOCTURNALLY INCREASING
SOUTHWESTERLY LOW LEVEL JET...AS A LONGER PERSISTENCE/POTENTIAL
EASTWARD EXPANSION OF TSTMS SEEMS LIKELY TO OCCUR THIS EVENING
ALONG/NORTHEAST OF THE WARM FRONT. SOME SEVERE HAIL CANNOT BE RULED
OUT IF STORMS ACQUIRE UPDRAFT ROTATION /FAVORABLE SHEAR PROFILES
NORTHEAST OF WARM FRONT/...ALTHOUGH RELATIVELY WARM THERMAL PROFILES
ALOFT AND ONLY MODERATE SOURCE REGION MUCAPE /1500-2000 J PER KG/
IMPLY THAT ANY SUCH THREAT SHOULD REMAIN LIMITED. MORE SO...HEAVY
RAINFALL MAY BE POSSIBLE.

..GUYER.. 07/29/2012

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

ATTN...WFO...EAX...OAX...TOP...GID...

LAT...LON   39479911 39859842 40949827 40849620 40479537 38949591
            39179744 39479911

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 29, 3:25 PM CDT	Mesoscale Discussion	SPC	Adair, Audrain, Clark, Knox, Lewis, Marion and 6 more	2 hr

Nearby

Mesoscale Discussions in Nebraska, 2012 Mesoscale Discussions in Kansas, 2012 Mesoscale Discussions in Missouri, 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.