Alert archive / Maine / Mesoscale Discussions in 2012

Mesoscale Discussion 2252

December 29, 20129 counties in Maine; Rockingham County, Strafford County, New Hampshire

The Storm Prediction Center issued this mesoscale discussion at Dec 29, 2012, 9:11 PM EST for 9 counties in Maine; Rockingham County, Strafford County, New Hampshire. It was in force for 6 hr.

The area

The outline as issued.

The facts

Issued: Dec 29, 2012, 9:11 PM EST (02:11 UTC)
Expired: Dec 30, 2012, 3:15 AM EST
In force: 6 hr
Issued by: the Storm Prediction Center

Counties Androscoggin County, ME, Cumberland County, ME, Hancock County, ME, Kennebec County, ME, Lincoln County, ME, Sagadahoc County, ME, Waldo County, ME, Washington County, ME, York County, ME, Rockingham County, NH, Strafford County, NH

The radar

The Portland,ME radar (KGYX), 89 km from the middle of the area, began a volume at 02:13 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 00:00Z, 2.2 hours before the alert went out and 89 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: 488 m above ground
0-6 km bulk shear: 75 kt
0-1 km storm-relative helicity: 196 m²/s²
0-3 km storm-relative helicity: 297 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.

756 
ACUS11 KWNS 300211
SWOMCD
SPC MCD 300211 
MEZ000-MAZ000-NHZ000-300815-

MESOSCALE DISCUSSION 2252
NWS STORM PREDICTION CENTER NORMAN OK
0811 PM CST SAT DEC 29 2012

AREAS AFFECTED...COASTAL AREAS OF ME AND NH

CONCERNING...HEAVY SNOW 

VALID 300211Z - 300815Z

SUMMARY...SNOWFALL RATES FROM 1 TO POSSIBLY 2 IN/HR ARE FORECAST TO
SPREAD FROM COASTAL AREAS OF NH NEWD ACROSS COASTAL AREAS OF ME
DURING THE 03 TO 12Z TIME PERIOD.

DISCUSSION...LATEST WV IMAGERY SHOWS A COMPACT UPPER DISTURBANCE
LOCATED S-SE OF CAPE COD. THIS WAVE IS FORECAST TO AMPLIFY TONIGHT
AS IT TAKES ON A NEGATIVE TILT OFFSHORE FROM ME. AS THIS
OCCURS...MIDLEVEL FRONTOGENESIS WILL STRENGTHEN DRAMATICALLY ALONG
THE COAST OF NH AND ME. THIS MESOSCALE FORCING FOR ASCENT COMBINED
WITH STRONG UPPER DIVERGENCE/LARGE-SCALE ASCENT WILL AID IN THE
DEVELOPMENT OF A DEEPLY SATURATED ENVIRONMENT WITH STRONG ASCENT
OCCURRING THROUGH THE DENDRITIC GROWTH ZONE. IN ADDITION...SURFACE
LOW PRESSURE ATTENDANT TO THE UPPER TROUGH WILL ADVANCE NEWD ACROSS
THE OFFSHORE WATERS...WHICH WILL FAVOR NLY LOW-LEVEL
WINDS...SUB-FREEZING BOUNDARY LAYER TEMPERATURES...AND A
PRECIPITATION TYPE OF SNOW. THUS...HEAVY SNOWFALL WITH RATES FROM 1
TO LOCALLY 2 IN/HR APPEAR PROBABLE OVER COASTAL PORTIONS OF NH AND
ME. SHORT TERM MODEL GUIDANCE INDICATES HEAVY SNOW WILL EXIT NH BY
06-09Z...AND EVENTUALLY BECOME CONFINED TO DOWNEAST ME DURING THE
06-12Z TIME PERIOD.

..GARNER.. 12/30/2012

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

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

LAT...LON   44676717 44076914 43767013 42897084 42747134 42897167
            44826968 45586775 45166707 44676717

Nearby

Mesoscale Discussions in Maine, 2012 Mesoscale Discussions in New Hampshire, 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.