Alert archive / Pennsylvania / Mesoscale Discussions in 2012

Mesoscale Discussion 957

May 29, 20124 states

The Storm Prediction Center issued this mesoscale discussion at May 29, 2012, 1:25 PM EDT for 4 states. It was in force for 65 min.

The area

The outline as issued.

The facts

Issued
May 29, 2012, 1:25 PM EDT (17:25 UTC)
Expired
May 29, 2012, 2:30 PM EDT
In force
65 min
Issued by
the Storm Prediction Center
All 62 counties

Allegany County, NY, Cattaraugus County, NY, Cayuga County, NY, Chautauqua County, NY, Erie County, NY, Genesee County, NY, Jefferson County, NY, Lewis County, NY, Livingston County, NY, Monroe County, NY, Onondaga County, NY, Ontario County, NY, Oswego County, NY, Schuyler County, NY, Seneca County, NY, Steuben County, NY, Wayne County, NY, Wyoming County, NY, Yates County, NY, Belmont County, OH, Carroll County, OH, Columbiana County, OH, Coshocton County, OH, Guernsey County, OH, Harrison County, OH, Jefferson County, OH, Mahoning County, OH, Muskingum County, OH, Noble County, OH, Portage County, OH, Stark County, OH, Trumbull County, OH, Tuscarawas County, OH, Allegheny County, PA, Armstrong County, PA, Beaver County, PA, Butler County, PA, Cambria County, PA, Cameron County, PA, Clarion County, PA, Clearfield County, PA, Crawford County, PA, Elk County, PA, Erie County, PA, Fayette County, PA, Forest County, PA, Greene County, PA, Indiana County, PA, Jefferson County, PA, Lawrence County, PA, McKean County, PA, Mercer County, PA, Potter County, PA, Somerset County, PA, Venango County, PA, Warren County, PA, Washington County, PA, Westmoreland County, PA, Brooke County, WV, Hancock County, WV, Marshall County, WV, Ohio County, WV

The radar

The Buffalo radar (KBUF), 104 km from the middle of the area, began a volume at 17:25 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

Buffalo Intl Airport, NY (KBUF), launched 12:00Z, 5.4 hours before the alert went out and 101 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, Buffalo Intl Airport, NY at 12:00Z on 2012-05-29Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1783 joules per kilogram.LCLLFCEL10008507005003002001001 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, Buffalo Intl Airport, NY at 12:00Z on 2012-05-29The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 71 square meters per square second.19395878Sfc1 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
1783 J/kg
Mixed-layer CIN
-53 J/kg
Mixed-layer LCL
1124 m above ground
0-6 km bulk shear
37 kt
0-1 km storm-relative helicity
71 m²/s²
0-3 km storm-relative helicity
128 m²/s²
Significant tornado parameter
0.5
Supercell composite
2.0

Open this sounding in Storm Lab

The text

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

634 
ACUS11 KWNS 291725
SWOMCD
SPC MCD 291725 
NYZ000-PAZ000-WVZ000-OHZ000-291830-

MESOSCALE DISCUSSION 0957
NWS STORM PREDICTION CENTER NORMAN OK
1225 PM CDT TUE MAY 29 2012

AREAS AFFECTED...ERN OH...WRN PA/NY

CONCERNING...SEVERE THUNDERSTORM WATCH 312...

VALID 291725Z - 291830Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 312
CONTINUES.

SUMMARY...PRE-FRONTAL CONVECTION WILL CONTINUE TO PROGRESS
EWD...PRODUCING DMGG WINDS AND HAIL. ADDITIONAL DEVELOPMENT MAY BE
POSSIBLE WITHIN THE WW AREA ALONG THE ALLEGHENIES.

DISCUSSION...A FEW BROKEN LINES OF STRONG TO SEVERE CONVECTION
CONTINUE ACROSS THE WW AREA. 17Z VISIBLE IMAGERY REFLECTS A LEADING
OUTFLOW BOUNDARY THAT IS INITIATING NEW CONVECTION AS IT SURGES EWD.
TEMPERATURES TO THE E HAVE WARMED VERY QUICKLY INTO THE MID
80S...WITH A FEW LOWER 90S VALUES NOTED NEAR SYR. GIVEN THE RAPID
SURFACE-BASED DESTABILIZATION AND VERY STEEP LOW-LEVEL LAPSE RATES
/8.5-9 C/KM PER MESOANALYSIS/...THE DMGG WIND THREAT COULD BECOME
MORE WIDESPREAD WITH TIME. WITH HEIGHT FALLS AND INCREASING FORCING
FOR ASCENT WITH THE APPROACHING TROUGH...THE ONGOING CONVECTION MAY
EXPERIENCE RENEWED VIGOR THIS AFTERNOON AS IT PROGRESS INTO CNTRL NY
AND PA.

..HURLBUT.. 05/29/2012

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

ATTN...WFO...ALY...BGM...BUF...CTP...PBZ...RLX...CLE...ILN...

LAT...LON   39757888 39758231 40588186 41938049 43757751 43717648
            44147635 44377584 44047510 43667504 41897721 41097808
            39757888

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
May 29, 10:27 AM EDTSevere Thunderstorm WatchSPCAllegany, Cattaraugus, Cayuga, Chautauqua, Jefferson, Lewis and 11 more5 hr
May 29, 11:43 AM EDTMesoscale DiscussionSPCAlbany, Broome, Cayuga, Chemung, Chenango, Columbia and 26 more62 min
May 29, 12:01 PM EDTMesoscale DiscussionSPCAlbany, Broome, Chemung, Chenango, Columbia, Cortland and 19 more59 min
May 29, 12:26 PM EDTTornado WatchSPCAlbany, Clinton, Columbia, Dutchess, Essex, Franklin and 13 more8 hr
May 29, 1:03 PM EDTSevere Thunderstorm WatchSPCBroome, Chemung, Chenango, Cortland, Delaware, Madison and 5 more8 hr
May 29, 1:52 PM EDTMesoscale DiscussionSPCAlbany, Clinton, Columbia, Essex, Franklin, Fulton and 8 more53 min
May 29, 2:13 PM EDTMesoscale DiscussionSPCBroome, Chemung, Chenango, Cortland, Delaware, Dutchess and 10 more62 min
May 29, 3:12 PM EDTMesoscale DiscussionSPCBroome, Cayuga, Chemung, Chenango, Cortland, Delaware and 12 more63 min
May 29, 3:26 PM EDTMesoscale DiscussionSPCAlbany, Clinton, Columbia, Essex, Franklin, Fulton and 11 more64 min
May 29, 4:40 PM EDTMesoscale DiscussionSPCBroome, Delaware, Otsego, Sullivan65 min
May 29, 5:54 PM EDTSevere Thunderstorm WatchSPCBronx, Kings, New York, Orange, Putnam, Queens and 3 more3 hr
May 29, 7:01 PM EDTMesoscale DiscussionSPCBronx, Kings, New York, Putnam, Richmond, Rockland and 1 more89 min
May 29, 7:21 PM EDTMesoscale DiscussionSPCDutchess54 min
May 29, 9:48 AM EDTMesoscale DiscussionSPCBelmont, Carroll, Columbiana, Coshocton, Fairfield, Guernsey and 18 more87 min
May 29, 4:22 PM EDTMesoscale DiscussionSPCBerkeley, Hampshire, Hardy, Jefferson, Morgan, Pendleton53 min
May 29, 4:33 PM EDTSevere Thunderstorm WatchSPCBerkeley, Grant, Hampshire, Hardy, Jefferson, Mineral and 2 more4 hr

Nearby

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