Alert archive / Vermont / Mesoscale Discussions in 2012

Mesoscale Discussion 1845

August 31, 20124 states

The Storm Prediction Center issued this mesoscale discussion at Aug 31, 2012, 4:06 PM EDT for 4 states. It was in force for 54 min.

The area

The outline as issued.

The facts

Issued: Aug 31, 2012, 4:06 PM EDT (20:06 UTC)
Expired: Aug 31, 2012, 5:00 PM EDT
In force: 54 min
Issued by: the Storm Prediction Center
Chance of a watch: 60%

Counties Aroostook County, ME, Franklin County, ME, Penobscot County, ME, Piscataquis County, ME, Somerset County, ME, Coos County, NH, Clinton County, NY, Essex County, NY, Franklin County, NY, Addison County, VT, Caledonia County, VT, Chittenden County, VT, Essex County, VT, Franklin County, VT, Grand Isle County, VT, Lamoille County, VT, Orleans County, VT, Washington County, VT

The radar

The Portland,ME radar (KGYX), 193 km from the middle of the area, began a volume at 20:09 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

Gray, ME (KGYX), launched 12:00Z, 8.1 hours before the alert went out and 193 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: 3118 m above ground
0-6 km bulk shear: 47 kt
0-1 km storm-relative helicity: 188 m²/s²
0-3 km storm-relative helicity: 135 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.

821 
ACUS11 KWNS 312006
SWOMCD
SPC MCD 312006 
MEZ000-NHZ000-VTZ000-NYZ000-312100-

MESOSCALE DISCUSSION 1845
NWS STORM PREDICTION CENTER NORMAN OK
0306 PM CDT FRI AUG 31 2012

AREAS AFFECTED...UPSTATE NY TO PORTIONS OF NRN NEW ENGLAND

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

VALID 312006Z - 312100Z

PROBABILITY OF WATCH ISSUANCE...60 PERCENT

SUMMARY...A SEVERE WEATHER WATCH IS BEING CONSIDERED FOR PARTS OF
UPSTATE NY INTO NRN NEW ENGLAND LATE THIS AFTERNOON INTO THE
EVENING.  IF GREATER DESTABILIZATION CAN OCCUR IN THE PRE-FRONTAL
AIR MASS AS SUGGESTED BY THE 12Z NAM...THEN WW ISSUANCE WOULD BECOME
MORE LIKELY.

DISCUSSION...SATELLITE/RADAR IMAGERY SHOWED CU/TCU INCREASING IN
DEPTH ALONG THE SEWD ADVANCING COLD FRONT WITH LIGHTNING DATA
INDICATING A FEW TSTMS NORTH OF MAINE AND FARTHER SW IN FAR SRN
QUEBEC /AT 100 NNE MSS AND 100 NNW EFK/.  IN ADDITION TO THIS
ACTIVITY WHICH SHOULD REACH THE NH AND NWRN MAINE BORDER REGIONS
WITH CANADA BETWEEN 22-00Z...OBSERVATIONAL DATA ALSO ELEVATED
CONVECTION CURRENTLY MOVING ESEWD INTO FAR UPSTATE NY AND NWRN VT
ALONG THE INTERNATIONAL BORDER.  

KINEMATICS ARE FAVORABLE FOR STORM ORGANIZATION PER OBSERVATION OF A
70 KT WNWLY MIDLEVEL JET EVIDENT ON BTV WSR-88D VAD...AND A 30-40 KT
WSWLY LLJ EXTENDING INTO NRN NEW ENGLAND...RESULTING IN
STRENGTHENING BULK SHEAR OF 50+ KT.  MEANWHILE...THERMODYNAMICS ARE
CURRENTLY SOMEWHAT MEAGER ACROSS THE DISCUSSION AREA TO SUPPORT
STRONGER UPDRAFTS...LIKELY DUE TO PRE-FRONTAL CLOUDINESS NOW LOCATED
ACROSS FAR NRN VT INTO ADJACENT CANADA.  OBJECTIVE ANALYSES
INDICATED GRADUAL LOW LEVEL MOISTURE ADVECTION EWD FROM SRN ONTARIO
INTO UPSTATE NY AND NRN ENGLAND...WHICH MAY PROMOTE A MORE FAVORABLE
ENVIRONMENT/GREATER INSTABILITY FOR SUSTAINED UPDRAFTS AS THE COLD
FRONT REACHES THIS REGION AFTER 22-23Z.

..PETERS/CORFIDI.. 08/31/2012

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

ATTN...WFO...CAR...GYX...BTV...

LAT...LON   47086788 45846777 44717003 44097224 43817367 44437450
            45087465 45187299 45317172 45837082 46497013 46926952
            47086788

Nearby

Mesoscale Discussions in Vermont, 2012 Mesoscale Discussions in Maine, 2012 Mesoscale Discussions in New York, 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; radar from the NEXRAD Level II archive.