Alert archive / Ohio / Mesoscale Discussions in 2012

Mesoscale Discussion 744

May 7, 20124 states

The Storm Prediction Center issued this mesoscale discussion at May 7, 2012, 1:40 PM EDT for 4 states. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: May 7, 2012, 1:40 PM EDT (17:40 UTC)
Expired: May 7, 2012, 3:45 PM EDT
In force: 2 hr
Issued by: the Storm Prediction Center
Chance of a watch: 40%

All 64 counties

Bath County, KY, Bourbon County, KY, Bracken County, KY, Carter County, KY, Fleming County, KY, Grant County, KY, Greenup County, KY, Harrison County, KY, Lewis County, KY, Mason County, KY, Nicholas County, KY, Pendleton County, KY, Robertson County, KY, Rowan County, KY, Adams County, OH, Athens County, OH, Belmont County, OH, Brown County, OH, Carroll County, OH, Clermont County, OH, Columbiana County, OH, Coshocton County, OH, Fairfield County, OH, Gallia County, OH, Guernsey County, OH, Harrison County, OH, Highland County, OH, Hocking County, OH, Jackson County, OH, Jefferson County, OH, Lawrence County, OH, Licking County, OH, Meigs County, OH, Monroe County, OH, Morgan County, OH, Muskingum County, OH, Noble County, OH, Perry County, OH, Pickaway County, OH, Pike County, OH, Ross County, OH, Scioto County, OH, Tuscarawas County, OH, Vinton County, OH, Washington County, OH, Allegheny County, PA, Beaver County, PA, Fayette County, PA, Greene County, PA, Washington County, PA, Westmoreland County, PA, Brooke County, WV, Hancock County, WV, Marion County, WV, Marshall County, WV, Mason County, WV, Monongalia County, WV, Ohio County, WV, Pleasants County, WV, Ritchie County, WV, Tyler County, WV, Wetzel County, WV, Wirt County, WV, Wood County, WV

The radar

The Charleston,WV radar (KRLX), 142 km from the middle of the area, began a volume at 17:43 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

Pittsburgh, PA (KPIT), launched 12:00Z, 5.7 hours before the alert went out and 168 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: 180 J/kg
Mixed-layer CIN: -45 J/kg
Mixed-layer LCL: 805 m above ground
0-6 km bulk shear: 27 kt
0-1 km storm-relative helicity: 83 m²/s²
0-3 km storm-relative helicity: 74 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.2

Open this sounding in Storm Lab

The text

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

925 
ACUS11 KWNS 071740
SWOMCD
SPC MCD 071740 
PAZ000-WVZ000-OHZ000-KYZ000-071945-

MESOSCALE DISCUSSION 0744
NWS STORM PREDICTION CENTER NORMAN OK
1240 PM CDT MON MAY 07 2012

AREAS AFFECTED...SRN AND ERN OH...FAR NRN KY....SWRN PA....FAR NRN
WV

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

VALID 071740Z - 071945Z

PROBABILITY OF WATCH ISSUANCE...40 PERCENT

SUMMARY...THUNDERSTORMS ARE EXPECTED TO INCREASE EARLY THIS
AFTERNOON. STRONG TO SEVERE WIND GUSTS WILL BE THE MAIN THREAT BUT
ISOLATED INSTANCES OF MARGINALLY SEVERE HAIL WILL BE POSSIBLE WITH
STRONGER CELLS INTO THE EARLY EVENING. CONVECTIVE TRENDS WILL BE
MONITORED FOR A POSSIBLE WW.

DISCUSSION...THUNDERSTORMS WERE BEGINNING TO DEVELOP ALONG AN
OUTFLOW BOUNDARY PRODUCED BY OVERNIGHT CONVECTION ACROSS CNTRL OHIO.
TEMPERATURES HAVE WARMED INTO THE UPPER 70S TO LOW 80S EARLY THIS
AFTERNOON AND WITH DEWPOINTS IN THE LOW TO MID 60S...THE AIR MASS
HAS BECOME MODERATELY UNSTABLE AND UNCAPPED. A BROAD CU FIELD WAS
ALSO NOTED ON 17Z VISIBLE SATELLITE IMAGERY AND A FEW THUNDERSTORMS
HAD ALSO DEVELOP ACROSS SWRN PA IN THE VICINITY OF A NWD RETREATING
WARM FRONT. THIS AREA MAY ALSO SERVE AS ANOTHER FOCUS FOR SEVERE
THUNDERSTORM DEVELOPMENT INTO THE AFTERNOON AND EARLY EVENING HOURS.
DEEP LAYER FLOW ACROSS THE REGION REMAINS FAIRLY WEAK...AROUND 20-30
KT...AND THIS WILL LEAD TO MAINLY MULTICELL CLUSTERS AHEAD OF THE
OUTFLOW BOUNDARY. SHOULD STORMS ORGANIZE ALONG THE BOUNDARY THEY
WOULD POSE A GREAT RISK FOR DAMAGING WIND GUSTS. IN ADDITION TO THE
WEAK SHEAR ENVIRONMENT...WEAK MIDLEVEL LAPSE RATES MAY SOMEWHAT
INHIBIT STORM ORGANIZATION/UPDRAFT STRENGTH DESPITE THE
UNSTABLE/MOIST ENVIRONMENT AND THEREFORE ONLY A MARGINAL SEVERE HAIL
THREAT IS EXPECTED. STEEP LOW LEVEL LAPSE RATES AND HIGH PW VALUES
WILL AID IN GUSTY WIND POTENTIAL WITH ALL STORMS HOWEVER AND THIS IS
EXPECTED TO BE THE MAIN THREAT INTO THE EARLY EVENING HOURS.
CONVECTIVE TRENDS WILL BE MONITORED FOR A POTENTIAL WW THIS
AFTERNOON.

..LEITMAN/MEAD.. 05/07/2012

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

ATTN...WFO...CTP...PBZ...RLX...CLE...JKL...ILN...LMK...

LAT...LON   40348217 39218392 38798462 38568469 38318458 38098410
            38108345 38378274 38598227 39168101 39558001 39867940
            40247913 40437918 40697929 40847965 40858009 40858083
            40588182 40348217

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 7, 4:09 PM EDT	Mesoscale Discussion	SPC	Boone, Bullitt, Campbell, Carroll, Gallatin, Grant and 9 more	96 min

Nearby

Mesoscale Discussions in Ohio, 2012 Mesoscale Discussions in Kentucky, 2012 Mesoscale Discussions in West Virginia, 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.