Alert archive / Pennsylvania / Mesoscale Discussions in 2012

Mesoscale Discussion 1597

July 26, 201210 counties in New York; 11 counties in Ohio; 12 counties in Pennsylvania

The Storm Prediction Center issued this mesoscale discussion at Jul 26, 2012, 1:15 AM EDT for 10 counties in New York; 11 counties in Ohio; 12 counties in Pennsylvania. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued
Jul 26, 2012, 1:15 AM EDT (05:15 UTC)
Expired
Jul 26, 2012, 3:15 AM EDT
In force
2 hr
Issued by
the Storm Prediction Center
Chance of a watch
60%
All 33 counties

Allegany County, NY, Cattaraugus County, NY, Chautauqua County, NY, Erie County, NY, Genesee County, NY, Livingston County, NY, Ontario County, NY, Steuben County, NY, Wyoming County, NY, Yates County, NY, Ashtabula County, OH, Columbiana County, OH, Cuyahoga County, OH, Geauga County, OH, Lake County, OH, Mahoning County, OH, Medina County, OH, Portage County, OH, Stark County, OH, Summit County, OH, Trumbull County, OH, Butler County, PA, Clarion County, PA, Crawford County, PA, Elk County, PA, Erie County, PA, Forest County, PA, Lawrence County, PA, McKean County, PA, Mercer County, PA, Potter County, PA, Venango County, PA, Warren County, PA

The radar

The Buffalo radar (KBUF), 129 km from the middle of the area, began a volume at 05:18 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 00:00Z, 5.3 hours before the alert went out and 176 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-pSkew-T log-p diagram, Pittsburgh, PA at 00:00Z on 2012-07-26Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Pittsburgh, PA at 00:00Z on 2012-07-26The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 82 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
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
2457 m above ground
0-6 km bulk shear
48 kt
0-1 km storm-relative helicity
82 m²/s²
0-3 km storm-relative helicity
169 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.

705 
ACUS11 KWNS 260515
SWOMCD
SPC MCD 260515 
NYZ000-PAZ000-OHZ000-260715-

MESOSCALE DISCUSSION 1597
NWS STORM PREDICTION CENTER NORMAN OK
1215 AM CDT THU JUL 26 2012

AREAS AFFECTED...FAR NORTHERN OH/NORTHWEST PA/WESTERN NY

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

VALID 260515Z - 260715Z

PROBABILITY OF WATCH ISSUANCE...60 PERCENT

SUMMARY...AT LEAST ISOLATED DAMAGING WIND/SEVERE HAIL POTENTIAL IS
LIKELY TO DEVELOP INTO PORTIONS OF FAR NORTHERN OH AND /MORE SO/
NORTHWEST PA AND WESTERN NY OVERNIGHT. A SEVERE TSTM WATCH MAY BE
NEEDED.

DISCUSSION...A QUASI-LINEAR MCS CONTINUES TO DEVELOP/EXPAND AND
GRADUALLY ACCELERATE SOUTHEASTWARD ACROSS LOWER MI/SOUTHERN ONTARIO
AS OF 05Z. THIS ACTIVITY SEEMS LIKELY TO PERSIST EAST-SOUTHEASTWARD
OVERNIGHT WITHIN A BELT OF MODERATELY STRONG LOW-MID LEVEL
FLOW...POTENTIALLY INTO PARTS OF NORTHERN OH/NORTHWEST PA/WESTERN
NY...PERHAPS AS EARLY AS 07Z-08Z NEAR THE LOWER LAKES. PRECEDING THE
MCS...IT IS YET RELATIVELY DRY/STABLE AS PER THE 00Z OBSERVED
SOUNDING FROM BUFFALO/PITTSBURGH. HOWEVER...A WARM FRONT CONTINUES
TO STEADILY APPROACH THE REGION FROM THE WEST WITH AID OF A 30-40 KT
LOW LEVEL JET PER REGIONAL WSR-88D VWPS ACROSS INDIANA/OH/MI...WITH
THE CONTINUED EAST-NORTHEASTWARD ADVECTION OF A POTENTIALLY UNSTABLE
AIRMASS AS SAMPLED BY THE 00Z WILMINGTON OH OBSERVED RAOB /5000+ J
PER KG MLCAPE/. WITH GREATER ACCESS TO WARM/MOIST ADVECTION JUST
ABOVE THE SURFACE...AT LEAST THE WEST-SOUTHWESTERN FLANK OF THE
APPROACHING MCS MAY POSE A DAMAGING WIND/PERHAPS SEVERE HAIL RISK
OVERNIGHT INTO PORTIONS OF OH/PA/NY.

..GUYER/THOMPSON.. 07/26/2012

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

ATTN...WFO...BGM...BUF...CTP...PBZ...CLE...

LAT...LON   42628006 43127831 43117701 42607688 41987734 41227907
            41187927 40698041 40618103 41258253 41918113 42628006

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jul 26, 4:31 AM EDTMesoscale DiscussionSPCAllegany, Cattaraugus, Chautauqua, Chemung, Livingston, Ontario and 5 more89 min
Jul 26, 12:26 PM EDTMesoscale DiscussionSPCAllegany, Cattaraugus, Chautauqua, Chemung, Schuyler, Steuben2 hr
Jul 26, 1:16 PM EDTSevere Thunderstorm WatchSPCAllegany, Cattaraugus, Chautauqua9 hr
Jul 26, 1:50 PM EDTMesoscale DiscussionSPCAlbany, Broome, Chemung, Chenango, Columbia, Cortland and 22 more115 min
Jul 26, 2:10 PM EDTTornado WatchSPCAlbany, Broome, Cayuga, Chemung, Chenango, Columbia and 26 more6 hr
Jul 26, 3:37 PM EDTMesoscale DiscussionSPCBronx, Cattaraugus, Kings, Nassau, New York, Orange and 6 more113 min
Jul 26, 3:57 PM EDTSevere Thunderstorm WatchSPCBronx, Kings, Nassau, New York, Orange, Putnam and 5 more6 hr
Jul 26, 6:04 PM EDTMesoscale DiscussionSPCBronx, Columbia, Dutchess, Kings, Nassau, New York and 9 more86 min
Jul 26, 7:28 PM EDTMesoscale DiscussionSPCBronx, Dutchess, Kings, Nassau, New York, Putnam and 5 more92 min
Jul 26, 6:06 PM EDTMesoscale DiscussionSPCAthens, Belmont, Gallia, Guernsey, Harrison, Jackson and 9 more84 min

Nearby

Mesoscale Discussions in Pennsylvania, 2012Mesoscale Discussions in Ohio, 2012Mesoscale Discussions in New York, 2012Every 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.