Alert archive / Pennsylvania / Mesoscale Discussions in 2012

Mesoscale Discussion 966

May 29, 20124 counties in New Jersey; 4 counties in New York; 28 counties in Pennsylvania

The Storm Prediction Center issued this mesoscale discussion at May 29, 2012, 4:40 PM EDT for 4 counties in New Jersey; 4 counties in New York; 28 counties in Pennsylvania. It was in force for 65 min.

The area

The outline as issued.

The facts

Issued
May 29, 2012, 4:40 PM EDT (20:40 UTC)
Expired
May 29, 2012, 5:45 PM EDT
In force
65 min
Issued by
the Storm Prediction Center
All 36 counties

Hunterdon County, NJ, Morris County, NJ, Sussex County, NJ, Warren County, NJ, Broome County, NY, Delaware County, NY, Otsego County, NY, Sullivan County, NY, Adams County, PA, Berks County, PA, Bucks County, PA, Carbon County, PA, Chester County, PA, Columbia County, PA, Cumberland County, PA, Dauphin County, PA, Franklin County, PA, Lackawanna County, PA, Lancaster County, PA, Lebanon County, PA, Lehigh County, PA, Luzerne County, PA, Monroe County, PA, Montgomery County, PA, Montour County, PA, Northampton County, PA, Northumberland County, PA, Perry County, PA, Pike County, PA, Schuylkill County, PA, Snyder County, PA, Sullivan County, PA, Susquehanna County, PA, Wayne County, PA, Wyoming County, PA, York County, PA

The radar

The Binghamton radar (KBGM), 130 km from the middle of the area, began a volume at 20:40 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 watches that followed

Watches SPC issued over any of the same counties within four hours of this discussion.

The nearest sounding before it

Phillips Aaf/Abe, MD (KAPG), launched 12:00Z, 8.7 hours before the alert went out and 186 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, Phillips Aaf/Abe, MD at 12:00Z on 2012-05-29Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 667 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, Phillips Aaf/Abe, MD at 12:00Z on 2012-05-29The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -39 square meters per square second.1939Sfc1 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
667 J/kg
Mixed-layer CIN
-217 J/kg
Mixed-layer LCL
1153 m above ground
0-6 km bulk shear
6 kt
0-1 km storm-relative helicity
-39 m²/s²
0-3 km storm-relative helicity
-10 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.

834 
ACUS11 KWNS 292041
SWOMCD
SPC MCD 292040
NYZ000-NJZ000-PAZ000-DEZ000-292145-

MESOSCALE DISCUSSION 0966
NWS STORM PREDICTION CENTER NORMAN OK
0340 PM CDT TUE MAY 29 2012

AREAS AFFECTED...ERN PA...SERN NY

CONCERNING...SEVERE THUNDERSTORM WATCH 315...

VALID 292040Z - 292145Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 315
CONTINUES.

SUMMARY...THREAT OF DMGG WIND AND HAIL PERSISTS ACROSS SEVERE WW
315. STABLE AREAS IN THE WAKE OF THE PRE-FRONTAL LINE OF CONVECTION
MAY BE CLEARED. AREAS DOWNSTREAM ARE STILL BEING MONITORED FOR A
POTENTIAL WW.

DISCUSSION...A BROKEN LINE OF CONVECTION CONTINUES TO PROGRESS
EWD...AND HAS MOVED OUT OF SEVERE WW312. ACROSS SERN NY...AN OUTFLOW
BOUNDARY FROM CONVECTION OVER THE CATSKILLS IS SURGING NWWD...AND
MAY LOCALLY ENHANCE THE STRENGTH OF THE STORMS TO THE W AS THE
BOUNDARIES MERGE. OTHERWISE...THE AIR MASS ACROSS SERN NY INTO WRN
MA REMAINS MODERATELY UNSTABLE...AND WILL CONTINUE TO SUPPORT SEVERE
WINDS AND HAIL.

FARTHER S...AREA VAD WIND PROFILE DATA SUGGESTS THAT THE STRONGER
LOW-LEVEL WINDS REMAIN BEHIND THE PRIMARY LINE OF CONVECTION.
HOWEVER...STEEP LOW-LEVEL LAPSE RATES ACROSS ERN PA INTO NJ MAY
STILL SUPPORT A DMGG WIND THREAT. AREAS TO THE EAST OF WW315 ARE
BEING MONITORED FOR A POSSIBLE WW. ALTHOUGH NOCTURNAL COOLING WILL
GRADUALLY STABILIZE THE BOUNDARY LAYER...SEASONABLY WARM/HUMID
CONDITIONS AND WARM ADVECTION REGIME MAY LEAD TO A SLOWER THAN
TYPICAL DEVELOPMENT OF THE INVERSION.

..HURLBUT.. 05/29/2012

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

ATTN...WFO...OKX...ALY...PHI...BGM...CTP...

LAT...LON   39777573 39787785 41707646 42877500 42257448 41687450
            40827446 39777573

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
May 29, 2:13 PM EDTMesoscale DiscussionSPCBergen, Essex, Hunterdon, Mercer, Morris, Passaic and 4 more62 min
May 29, 5:54 PM EDTSevere Thunderstorm WatchSPCBergen, Burlington, Camden, Essex, Gloucester, Hudson and 11 more3 hr
May 29, 7:01 PM EDTMesoscale DiscussionSPCBergen, Burlington, Essex, Hudson, Hunterdon, Mercer and 6 more89 min
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, 1:25 PM EDTMesoscale DiscussionSPCAllegany, Cattaraugus, Cayuga, Chautauqua, Erie, Genesee and 13 more65 min
May 29, 1:52 PM EDTMesoscale DiscussionSPCAlbany, Clinton, Columbia, Essex, Franklin, Fulton and 8 more53 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, 7:21 PM EDTMesoscale DiscussionSPCDutchess54 min
May 29, 9:48 AM EDTMesoscale DiscussionSPCAllegheny, Armstrong, Beaver, Butler, Clarion, Clearfield and 8 more87 min

Nearby

Mesoscale Discussions in Pennsylvania, 2012Mesoscale Discussions in New Jersey, 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.