Alert archive / New York / Mesoscale Discussions in 2012

Mesoscale Discussion 1900

September 6, 201226 counties in New York; McKean County, Potter County, Pennsylvania

The Storm Prediction Center issued this mesoscale discussion at Sep 6, 2012, 1:04 PM EDT for 26 counties in New York; McKean County, Potter County, Pennsylvania. It was in force for 56 min.

The area

The outline as issued.

The facts

Issued: Sep 6, 2012, 1:04 PM EDT (17:04 UTC)
Expired: Sep 6, 2012, 2:00 PM EDT
In force: 56 min
Issued by: the Storm Prediction Center
Chance of a watch: 40%

All 28 counties

Allegany County, NY, Cattaraugus County, NY, Cayuga County, NY, Chemung County, NY, Clinton County, NY, Cortland County, NY, Erie County, NY, Essex County, NY, Franklin County, NY, Genesee County, NY, Hamilton County, NY, Herkimer County, NY, Lewis County, NY, Livingston County, NY, Madison County, NY, Oneida County, NY, Onondaga County, NY, Ontario County, NY, Oswego County, NY, Schuyler County, NY, Seneca County, NY, St. Lawrence County, NY, Steuben County, NY, Tompkins County, NY, Wyoming County, NY, Yates County, NY, McKean County, PA, Potter County, PA

The watches that followed

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

Severe Thunderstorm Watch 626Sep 6, 2:50 PM EDT

The nearest sounding before it

Buffalo Intl Airport, NY (KBUF), launched 12:00Z, 5.1 hours before the alert went out and 157 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: 1594 J/kg
Mixed-layer CIN: -12 J/kg
Mixed-layer LCL: 693 m above ground
0-6 km bulk shear: 36 kt
0-1 km storm-relative helicity: 79 m²/s²
0-3 km storm-relative helicity: 161 m²/s²
Significant tornado parameter: 0.9
Supercell composite: 4.8

Open this sounding in Storm Lab

The text

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

242 
ACUS11 KWNS 061705
SWOMCD
SPC MCD 061704
VTZ000-NYZ000-PAZ000-061800-

MESOSCALE DISCUSSION 1900
NWS STORM PREDICTION CENTER NORMAN OK
1204 PM CDT THU SEP 06 2012

AREAS AFFECTED...WRN/CNTRL AND UPSTATE NY

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 061704Z - 061800Z

PROBABILITY OF WATCH ISSUANCE...40 PERCENT

SUMMARY...THUNDERSTORMS MAY INITIATE OVER THE NEXT HOUR OR TWO.
SEVERAL BOWING SEGMENTS CAPABLE OF PRODUCING DMGG WIND WILL BE
POSSIBLE WHEN/IF STORMS CAN BECOME SUSTAINED. THE AREA IS BEING
MONITORED FOR A POSSIBLE WW.

DISCUSSION...12Z BUF/PIT SOUNDINGS INDICATED CONVECTIVE TEMPERATURES
BETWEEN 78 AND 83 F...AND WITH INITIALLY CLEAR SKIES...DIURNAL
HEATING HAS BEEN MORE THAN SUFFICIENT FOR TEMPERATURES TO QUICKLY
RISE TO THESE VALUES. AS LOW-LEVEL LAPSE RATES CONTINUE TO
STEEPEN...CU NOW NOTED ON 1630Z VISIBLE IMAGERY WILL GRADUALLY
BECOME MORE VERTICALLY DEVELOPED WITH TIME. SEVERAL SURFACE FEATURES
EXIST FOR INITIAL DEVELOPMENT TO OCCUR...INCLUDING A LK BREEZE
BEGINNING TO FORM ALONG THE LEEWARD SHORES OF LK ONTARIO...AN AREA
OF CONVERGENCE N OF LK ERIE WHERE LIGHTNING HAS RECENTLY BEEN
NOTED...A MOISTURE GRADIENT W OF OTTAWA...AND OROGRAPHIC LIFT ALONG
THE ADIRONDACKS. ALTHOUGH 1630Z WV IMAGERY SHOWS SUBTLE
MOISTENING/IMPLIED ASCENT APPROACHING WRN NY...THE UPPER LEVEL
FORCING FOR ASCENT REMAINS WEAK AT BEST. HOWEVER...STEEP LOW-LEVEL
LAPSE RATES AND MODEST DEEP-LAYER WLY FLOW MAY SUPPORT SEVERAL SMALL
BOWING SEGMENTS CAPABLE OF DMGG WINDS SHOULD CONVECTION BECOME
BETTER ORGANIZED.

..HURLBUT/CORFIDI.. 09/06/2012

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

ATTN...WFO...BTV...ALY...BGM...BUF...CTP...

LAT...LON   42077922 42767892 43117892 43277782 43047682 43357630
            44327565 44937486 45057342 44527328 43597428 42327598
            41697809 41687915 42077922

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Sep 6, 2:50 PM EDT	Severe Thunderstorm Watch	SPC	Allegany, Broome, Cattaraugus, Cayuga, Chemung, Chenango and 26 more	6 hr
Sep 6, 4:27 PM EDT	Mesoscale Discussion	SPC	Allegany, Broome, Chemung, Chenango, Clinton, Cortland and 14 more	63 min
Sep 6, 6:45 PM EDT	Mesoscale Discussion	SPC	Broome, Chemung, Chenango, Cortland, Delaware, Montgomery and 6 more	60 min

Nearby

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