Alert archive / Vermont / Mesoscale Discussions in 2011

Mesoscale Discussion 995

May 27, 20115 states

The Storm Prediction Center issued this mesoscale discussion at May 27, 2011, 1:18 PM EDT for 5 states. It was in force for 87 min.

The area

The outline as issued.

The facts

Issued: May 27, 2011, 1:18 PM EDT (17:18 UTC)
Expired: May 27, 2011, 2:45 PM EDT
In force: 87 min
Issued by: the Storm Prediction Center

All 27 counties

Franklin County, MA, Franklin County, ME, Oxford County, ME, Penobscot County, ME, Somerset County, ME, Belknap County, NH, Carroll County, NH, Cheshire County, NH, Coos County, NH, Grafton County, NH, Hillsborough County, NH, Merrimack County, NH, Strafford County, NH, Sullivan County, NH, Washington County, NY, Addison County, VT, Bennington County, VT, Caledonia County, VT, Chittenden County, VT, Essex County, VT, Lamoille County, VT, Orange County, VT, Orleans County, VT, Rutland County, VT, Washington County, VT, Windham County, VT, Windsor County, VT

The radar

The Portland,ME radar (KGYX), 100 km from the middle of the area, began a volume at 17:23 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.

Severe Thunderstorm Watch 389May 27, 2:00 PM EDT

The nearest sounding before it

Gray, ME (KGYX), launched 12:00Z, 5.3 hours before the alert went out and 100 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 625 m above ground
0-6 km bulk shear: 46 kt
0-1 km storm-relative helicity: 8 m²/s²
0-3 km storm-relative helicity: 50 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.

380 
ACUS11 KWNS 271718
SWOMCD
SPC MCD 271718 
MEZ000-NHZ000-MAZ000-VTZ000-NYZ000-271845-

MESOSCALE DISCUSSION 0995
NWS STORM PREDICTION CENTER NORMAN OK
1218 PM CDT FRI MAY 27 2011

AREAS AFFECTED...VT...NH...ME..MA

CONCERNING...SEVERE POTENTIAL...WATCH LIKELY 

VALID 271718Z - 271845Z

A SEVERE THREAT IS EXPECTED TO DEVELOP ACROSS NEW ENGLAND THIS
AFTERNOON AS STORMS INITIATE AND INCREASE IN COVERAGE. WIND DAMAGE
AND HAIL SHOULD BE THE PRIMARY THREATS. WW ISSUANCE WILL LIKELY BE
NECESSARY OVER THE NEXT HOUR.

SFC ANALYSIS SHOWS THE NRN EDGE OF A POCKET OF LOW-LEVEL MOISTURE
OVER NEW ENGLAND. SFC DEWPOINTS IN NEW ENGLAND ARE IN THE LOWER TO
MID 60S F AND MESOANALYSIS SUGGESTS MODERATE INSTABILITY IS ALREADY
IN PLACE ACROSS THE SRN HALF OF NEW ENGLAND. WATER VAPOR IMAGERY AND
RUC ANALYSIS HAVE A PRONOUNCED VORTICITY MAXIMA OVER NRN PA AND
CNTRL NY. LIFT FROM THIS FEATURE ALONG WITH SFC HEATING WILL AID
WIDESPREAD THUNDERSTORM DEVELOPMENT BENEATH THE AXIS OF A
WELL-DEFINED 700 MB JET. THIS FEATURE IS HELPING TO CREATE STRONG
DEEP LAYER SHEAR PROFILES WHICH WILL BE FAVORABLE FOR SEVERE STORMS.
THE STORMS ARE FORECAST TO MOVE NEWD AT 35 TO 40 KT WHICH MAY AID
THE POTENTIAL FOR WIND DAMAGE. HAIL WILL ALSO BE POSSIBLE ESPECIALLY
WITH STORMS THAT HAVE ACCESS TO MAXIMIZED INSTABILITY.

..BROYLES.. 05/27/2011

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

ATTN...WFO...CAR...GYX...BOX...BTV...ALY...

LAT...LON   45846952 45237121 44937262 44267341 43027357 42577308
            42477221 42957122 43827065 45436864 45846952

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 27, 2:00 PM EDT	Severe Thunderstorm Watch	SPC	Androscoggin, Cumberland, Franklin, Hancock, Kennebec, Knox and 8 more	6 hr
May 27, 5:49 PM EDT	Mesoscale Discussion	SPC	Androscoggin, Cumberland, Franklin, Kennebec, Lincoln, Oxford and 6 more	56 min
May 27, 12:24 PM EDT	Mesoscale Discussion	SPC	Berkshire	96 min
May 27, 12:57 PM EDT	Severe Thunderstorm Watch	SPC	Broome, Chemung, Chenango, Cortland, Delaware, Madison and 5 more	9 hr
May 27, 6:14 PM EDT	Mesoscale Discussion	SPC	Broome, Chemung, Chenango, Cortland, Delaware, Fulton and 10 more	2 hr

Nearby

Mesoscale Discussions in Vermont, 2011 Mesoscale Discussions in New Hampshire, 2011 Mesoscale Discussions in Maine, 2011 Every mesoscale discussion in 2011

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.