Alert archive / Ohio / Mesoscale Discussions in 2007

Mesoscale Discussion 1237

June 21, 200739 counties in Ohio; 11 counties in Pennsylvania; 4 counties in West Virginia

The Storm Prediction Center issued this mesoscale discussion at Jun 21, 2007, 2:12 PM EDT for 39 counties in Ohio; 11 counties in Pennsylvania; 4 counties in West Virginia. It was in force for 93 min.

The area

The outline as issued.

The facts

Issued: Jun 21, 2007, 2:12 PM EDT (18:12 UTC)
Expired: Jun 21, 2007, 3:45 PM EDT
In force: 93 min
Issued by: the Storm Prediction Center

All 54 counties

Ashland County, OH, Belmont County, OH, Carroll County, OH, Columbiana County, OH, Coshocton County, OH, Crawford County, OH, Cuyahoga County, OH, Delaware County, OH, Erie County, OH, Geauga County, OH, Guernsey County, OH, Hancock County, OH, Hardin County, OH, Harrison County, OH, Holmes County, OH, Huron County, OH, Jefferson County, OH, Knox County, OH, Lake County, OH, Licking County, OH, Lorain County, OH, Lucas County, OH, Mahoning County, OH, Marion County, OH, Medina County, OH, Morrow County, OH, Muskingum County, OH, Ottawa County, OH, Portage County, OH, Richland County, OH, Sandusky County, OH, Seneca County, OH, Stark County, OH, Summit County, OH, Trumbull County, OH, Tuscarawas County, OH, Wayne County, OH, Wood County, OH, Wyandot County, OH, Allegheny County, PA, Armstrong County, PA, Beaver County, PA, Butler County, PA, Fayette County, PA, Indiana County, PA, Lawrence County, PA, Mercer County, PA, Venango County, PA, Washington County, PA, Westmoreland County, PA, Brooke County, WV, Hancock County, WV, Marshall County, WV, Ohio County, WV

The radar

The Cleveland radar (KCLE), 55 km from the middle of the area, began a volume at 18:12 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.

The nearest sounding before it

Pittsburgh, PA (KPIT), launched 12:00Z, 6.2 hours before the alert went out and 141 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 1857 m above ground
0-6 km bulk shear: 33 kt
0-1 km storm-relative helicity: 106 m²/s²
0-3 km storm-relative helicity: 131 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

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

000 
ACUS11 KWNS 211812
SWOMCD
SPC MCD 211812 
PAZ000-WVZ000-OHZ000-MIZ000-211945-

MESOSCALE DISCUSSION 1237
NWS STORM PREDICTION CENTER NORMAN OK
0112 PM CDT THU JUN 21 2007

AREAS AFFECTED...NRN OH...WRN PA

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

VALID 211812Z - 211945Z

AN ISOLATED SEVERE THREAT IS EXPECTED THIS AFTERNOON WITH WIDELY SCT
TSTMS ALONG A SEWD-MOVING COLD FRONT. ALTHOUGH DEEP-LAYER SHEAR WILL
REMAIN STRONG...RELATIVELY MODEST INSTABILITY ALONG WITH RATHER
SPARSE CONVECTIVE COVERAGE MAY PRECLUDE THE NEED FOR A WW ISSUANCE. 

18Z SUBJECTIVE SURFACE ANALYSIS PLACES A COLD FRONT FROM AROUND 25 N
FWA TO NEAR TOL TO 60 W BUF. A FEW TSTMS HAVE RECENTLY DEVELOPED
ALONG THIS FRONT INVOF TOL...WITH MEASURED WIND GUSTS TO 40 KTS AT
TDZ. THROUGH THE AFTERNOON...LARGE-SCALE FORCING SHOULD WANE AS A
SHORT WAVE TROUGH OVER ERN ONTARIO MOVES FARTHER E OF THE REGION.
WEAK CONVERGENCE ALONG THE FRONT AND MODEST SURFACE-BASED
INSTABILITY MAY STILL SUPPORT ADDITIONAL TSTM DEVELOPMENT...HOWEVER
OVERALL CONVECTIVE COVERAGE SHOULD REMAIN WIDELY SCT AT BEST.
NEVERTHELESS...AROUND 50 KTS OF NWLY MID-LEVEL FLOW WILL CREATE A
FAVORABLE ENVIRONMENT FOR ROTATING UPDRAFTS WITH LARGE HAIL. WITH
TEMPERATURE/DEW POINT SPREADS NOW APPROACHING 25 TO 35
DEGREES...STEEP LOW-LEVEL LAPSE RATES WOULD ALSO AID IN DAMAGING
WIND POTENTIAL.

..GRAMS.. 06/21/2007

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

ATTN...WFO...CTP...PBZ...CLE...ILN...DTX...IWX...

41868177 41868152 41658020 41327954 40407888 39927932
39808094 39958207 40248298 40688403 41238410 41728372

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jun 21, 1:25 PM EDT	Mesoscale Discussion	SPC	Bradford, Lackawanna, Luzerne, Lycoming, Monroe, Pike and 5 more	95 min
Jun 21, 2:47 PM EDT	Severe Thunderstorm Watch	SPC	Bradford, Carbon, Lackawanna, Luzerne, Monroe, Pike and 3 more	7 hr
Jun 21, 5:58 PM EDT	Mesoscale Discussion	SPC	Lackawanna, Monroe, Northampton, Pike, Susquehanna, Wayne	62 min
Jun 21, 5:10 PM EDT	Severe Thunderstorm Watch	SPC	Berkeley, Grant, Hampshire, Hardy, Jefferson, Mineral and 1 more	4 hr

Nearby

Mesoscale Discussions in Ohio, 2007 Mesoscale Discussions in Pennsylvania, 2007 Mesoscale Discussions in West Virginia, 2007 Every mesoscale discussion in 2007

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.