Alert archive / Vermont / Mesoscale Discussions in 2021

Mesoscale Discussion 10

January 2, 20215 counties in Maine; Coos County, New Hampshire; 6 counties in Vermont

The Storm Prediction Center issued this mesoscale discussion at Jan 2, 2021, 8:04 AM EST for 5 counties in Maine; Coos County, New Hampshire; 6 counties in Vermont. It was in force for 4 hr.

The area

The outline as issued.

The facts

Issued
Jan 2, 2021, 8:04 AM EST (13:04 UTC)
Expired
Jan 2, 2021, 12:00 PM EST
In force
4 hr
Issued by
the Storm Prediction Center
Concerning
Heavy snow

Counties Franklin County, ME, Oxford County, ME, Penobscot County, ME, Piscataquis County, ME, Somerset County, ME, Coos County, NH, Caledonia County, VT, Essex County, VT, Franklin County, VT, Grand Isle County, VT, Lamoille County, VT, Orleans County, VT

The radar

The Portland,ME radar (KGYX), 168 km from the middle of the area, began a volume at 13:04 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, 1.1 hours before the alert went out and 168 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, Gray, ME at 12:00Z on 2021-01-02Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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, Gray, ME at 12:00Z on 2021-01-02The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 417 square meters per square second.1939587897117Sfc1 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
425 m above ground
0-6 km bulk shear
67 kt
0-1 km storm-relative helicity
417 m²/s²
0-3 km storm-relative helicity
842 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

410 
ACUS11 KWNS 021305
SWOMCD
SPC MCD 021304 
MEZ000-NHZ000-VTZ000-NYZ000-021700-

Mesoscale Discussion 0010
NWS Storm Prediction Center Norman OK
0704 AM CST Sat Jan 02 2021

Areas affected...northern VT and NH into portions of western and
central ME

Concerning...Heavy snow 

Valid 021304Z - 021700Z

SUMMARY...Heavy snow will shift eastward from northern VT/NH into
parts of western/central ME this morning. Snowfall rates around 1
inch per hour are expected, with some areas briefly seeing rates as
high as 2 inches per hour.

DISCUSSION...Areas of heavy snow are ongoing across parts of
northern VT and NH as a band of 700 mb frontogenesis strengthens
ahead of the midlevel trough/low. Strong forcing and a warm/moist
advection around 850-700 mb is aiding in a deep, saturated layer
extending vertically through the dendritic growth zone, enhancing
snowfall rates. As the midlevel trough develops eastward, heavy
snow, with rates around 1 to 2 inches per hour, will spread eastward
into parts of western and central ME through the morning hours.

..Leitman.. 01/02/2021

...Please see www.spc.noaa.gov for graphic product...

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

LAT...LON   45816757 45296782 44506976 44087079 44577340 44917345
            45167312 45357205 45657117 46237025 46576854 46316796
            45816757

Nearby

Mesoscale Discussions in Vermont, 2021Mesoscale Discussions in Maine, 2021Mesoscale Discussions in New Hampshire, 2021Every mesoscale discussion in 2021

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.