Alert archive / New York / Mesoscale Discussions in 2013

Mesoscale Discussion 1421

July 18, 201319 counties in New York

The Storm Prediction Center issued this mesoscale discussion at Jul 18, 2013, 12:07 PM EDT for 19 counties in New York. It was in force for 53 min.

The area

The outline as issued.

The facts

Issued: Jul 18, 2013, 12:07 PM EDT (16:07 UTC)
Expired: Jul 18, 2013, 1:00 PM EDT
In force: 53 min
Issued by: the Storm Prediction Center
Chance of a watch: 40%

Counties Allegany County, NY, Cattaraugus County, NY, Cayuga County, NY, Chautauqua County, NY, Erie County, NY, Genesee County, NY, Livingston County, NY, Monroe County, NY, Niagara County, NY, Onondaga County, NY, Ontario County, NY, Orleans County, NY, Schuyler County, NY, Seneca County, NY, Steuben County, NY, Tompkins County, NY, Wayne County, NY, Wyoming County, NY, Yates County, NY

The radar

The Buffalo radar (KBUF), 45 km from the middle of the area, began a volume at 16:09 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, 4.1 hours before the alert went out and 41 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: 3057 J/kg
Mixed-layer CIN: -20 J/kg
Mixed-layer LCL: 718 m above ground
0-6 km bulk shear: 26 kt
0-1 km storm-relative helicity: 35 m²/s²
0-3 km storm-relative helicity: 79 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 2.3

Open this sounding in Storm Lab

The text

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

354 
ACUS11 KWNS 181608
SWOMCD
SPC MCD 181607 
NYZ000-PAZ000-181700-

MESOSCALE DISCUSSION 1421
NWS STORM PREDICTION CENTER NORMAN OK
1107 AM CDT THU JUL 18 2013

AREAS AFFECTED...WRN NY...PORTIONS OF LAKE HURON AND LAKE ONTARIO

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

VALID 181607Z - 181700Z

PROBABILITY OF WATCH ISSUANCE...40 PERCENT

SUMMARY...WIDELY SCATTERED TO SCATTERED TSTMS ARE EXPECTED TO
DEVELOP DURING THE NEXT FEW HOURS. A FEW SVR TSTMS ARE POSSIBLE WITH
THE POTENTIAL FOR DAMAGING WINDS AND LARGE HAIL. A WW IS POSSIBLE IN
THE SHORT TERM...THOUGH MORE LIKELY AS THE AFTN PROGRESSES.

DISCUSSION...INTENSE DIURNAL HEATING IS RESULTING IN STRONG
INSTABILITY ACROSS WRN NY AND ADJACENT PORTIONS OF LAKES HURON AND
ONTARIO WITH MLCAPES OF 3000 J/KG OR HIGHER AND NEGLIGIBLE CINH.
VISIBLE SATELLITE IMAGERY REVEALS AN EXPANDING CU FIELD WITH SOME
ENHANCEMENT THAT SUGGESTS TSTM DEVELOPMENT MAY BEGIN IN THE NEXT
COUPLE OF HOURS. THIS REGION IS ALONG THE SRN PERIPHERY OF STRONGER
DEEP-LAYER SHEAR...HOWEVER WITH AROUND 25-30 KTS OF 0-6 KM
SHEAR...ORGANIZED MULTICELLS ARE EXPECTED AS THE PRIMARY CONVECTIVE
MODE. INSTABILITY COUPLED WITH PW VALUES IN EXCESS OF 1.7 INCHES
SUGGESTS DAMAGING DOWNBURST WINDS WILL BE THE PRIMARY THREAT...WITH
LARGE HAIL ALSO POSSIBLE WITH THE STRONGEST UPDRAFTS. A WW IS
POSSIBLE IN THE SHORT TERM...AND MORE LIKELY LATER THIS AFTN AS
ORGANIZED TSTMS UPSTREAM POTENTIALLY IMPACT THIS AREA.

..BUNTING/CORFIDI.. 07/18/2013

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

ATTN...WFO...BGM...BUF...CLE...

LAT...LON   42537975 42797905 43347897 43607822 43597785 43517746
            43557688 43497634 42837614 42217659 42037747 42017923
            42037972 42267981 42537975

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 17, 8:28 PM EDT	Mesoscale Discussion	SPC	Clinton, Essex, Franklin, Hamilton, Herkimer, Jefferson and 2 more	62 min
Jul 18, 4:08 PM EDT	Mesoscale Discussion	SPC	Clinton, Essex, Franklin, St. Lawrence, Warren, Washington	67 min

Nearby

Mesoscale Discussions in New York, 2013 Every mesoscale discussion in 2013

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.