Alert archive / Maine / Mesoscale Discussions in 2018

Mesoscale Discussion 7

January 4, 20184 counties in Maine

The Storm Prediction Center issued this mesoscale discussion at Jan 4, 2018, 3:06 PM EST for 4 counties in Maine. It was in force for 5 hr.

The area

The outline as issued.

The facts

Issued: Jan 4, 2018, 3:06 PM EST (20:06 UTC)
Expired: Jan 4, 2018, 8:00 PM EST
In force: 5 hr
Issued by: the Storm Prediction Center

Counties Aroostook County, ME, Franklin County, ME, Piscataquis County, ME, Somerset County, ME

The radar

The Caribou radar (KCBW), 121 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

Caribou, ME (KCAR), launched 12:00Z, 8.1 hours before the alert went out and 149 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: 519 m above ground
0-6 km bulk shear: 93 kt
0-1 km storm-relative helicity: 284 m²/s²
0-3 km storm-relative helicity: 396 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

981 
ACUS11 KWNS 042007
SWOMCD
SPC MCD 042006 
MEZ000-NHZ000-050100-

Mesoscale Discussion 0007
NWS Storm Prediction Center Norman OK
0206 PM CST Thu Jan 04 2018

Areas affected...Northern ME

Concerning...Heavy snow 

Valid 042006Z - 050100Z

SUMMARY...Heavy snowfall rates in excess of 1"/hour will continue to
spread into portions of northern ME this afternoon and evening, with
higher snowfall rates of 2-3"/hour likely.  This heavy snow will
combine with strong winds to produce blizzard conditions across the
region.

DISCUSSION...The latest composite radar imagery shows heavy snow
bands moving northward into portions of northern ME, associated with
mid-level frontogenetic forcing (see previous MCD #6). Heavy snow is
being reported at several stations across the region, and these
conditions should continue into the evening. The period of at least
1"/hour snowfall rates appears most likely between 20z-03z.
Low-level warm air advection associated with the
approaching/deepening surface low should lead to steepening
mid-level lapse rates, with the potential for enhanced vertical
motion and heavy snowfall rates of 2-3"/hour rates possible between
21z-00z.

..Karstens/Peters.. 01/04/2018

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

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

LAT...LON   45216908 44796993 44617083 44877104 45287099 45667042
            46307009 46986973 47386899 47396816 47086772 46536769
            45846801 45496856 45216908

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jan 4, 11:34 AM EST	Mesoscale Discussion	SPC	Androscoggin, Cumberland, Franklin, Hancock, Kennebec, Knox and 8 more	5 hr
Jan 4, 4:50 PM EST	Mesoscale Discussion	SPC	Hancock, Washington	5 hr

Nearby

Mesoscale Discussions in Maine, 2018 Every mesoscale discussion in 2018

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.