Alert archive / Pennsylvania / Mesoscale Discussions in 2012

Mesoscale Discussion 1982

September 22, 2012Belmont County, Monroe County, Noble County, Ohio; 13 counties in Pennsylvania; Brooke County, Marshall County, Ohio County, West Virginia

The Storm Prediction Center issued this mesoscale discussion at Sep 22, 2012, 6:31 PM EDT for Belmont County, Monroe County, Noble County, Ohio; 13 counties in Pennsylvania; Brooke County, Marshall County, Ohio County, West Virginia. It was in force for 119 min.

The area

The outline as issued.

The facts

Issued: Sep 22, 2012, 6:31 PM EDT (22:31 UTC)
Expired: Sep 22, 2012, 8:30 PM EDT
In force: 119 min
Issued by: the Storm Prediction Center
Chance of a watch: 5%

Counties Belmont County, OH, Monroe County, OH, Noble County, OH, Allegheny County, PA, Armstrong County, PA, Beaver County, PA, Butler County, PA, Clarion County, PA, Elk County, PA, Forest County, PA, Greene County, PA, Indiana County, PA, Jefferson County, PA, McKean County, PA, Washington County, PA, Westmoreland County, PA, Brooke County, WV, Marshall County, WV, Ohio County, WV

The nearest sounding before it

Pittsburgh, PA (KPIT), launched 12:00Z, 10.5 hours before the alert went out and 36 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: 47 J/kg
Mixed-layer CIN: -7 J/kg
Mixed-layer LCL: 534 m above ground
0-6 km bulk shear: 60 kt
0-1 km storm-relative helicity: 155 m²/s²
0-3 km storm-relative helicity: 176 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.1

Open this sounding in Storm Lab

The text

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

881 
ACUS11 KWNS 222231
SWOMCD
SPC MCD 222231 
PAZ000-WVZ000-OHZ000-230030-

MESOSCALE DISCUSSION 1982
NWS STORM PREDICTION CENTER NORMAN OK
0531 PM CDT SAT SEP 22 2012

AREAS AFFECTED...ERN OH...WRN PA...NRN WV

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

VALID 222231Z - 230030Z

PROBABILITY OF WATCH ISSUANCE...5 PERCENT

SUMMARY...A FEW STRONG WINDS GUSTS WILL OCCUR WITH THE COLD
FRONT...BUT SEVERE WINDS ARE NOT EXPECTED TO BE WIDESPREAD.

DISCUSSION...A LINE OF SHOWERS AND EMBEDDED THUNDERSTORMS CONTINUED
TO MOVE RAPIDLY EWD ACROSS ERN OH AND INTO WRN PA. THIS IS A
STRONGLY FORCED SYSTEM ASSOCIATED WITH THE UPPER VORT MAX AND WITH
STRONG PRESSURE RISES BEHIND THE SECONDARY COLD FRONT. INSTABILITY
IS EXTREMELY WEAK...WITH JUST ENOUGH FOR SOME LIGHTNING STRIKES.
GIVEN RADAR TRENDS...A FEW SMALL BOWS WITHIN THE PRECIP AREA MAY BE
CAPABLE OF WIND GUSTS OF 30-45 KT...WINDS IN EXCESS OF 50 KT ARE
EXPECTED TO BE ISOLATED. PBZ RADAR DOES SHOW 40-50 KT WIND POTENTIAL
WITH THE STORMS CROSSING THE OH BORDER AS OF 2230Z.

..JEWELL/THOMPSON.. 09/22/2012

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

ATTN...WFO...CTP...PBZ...RLX...

LAT...LON   39728167 40358074 41048001 41567955 41967909 41947853
            41767808 41007850 40517889 40137938 39957992 39758049
            39638083 39728167

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Sep 22, 3:09 PM EDT	Mesoscale Discussion	SPC	Adams, Berks, Bucks, Carbon, Chester, Dauphin and 14 more	2 hr

Nearby

Mesoscale Discussions in Pennsylvania, 2012 Mesoscale Discussions in Ohio, 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.