Alert archive / New Hampshire / Mesoscale Discussions in 2017

Mesoscale Discussion 1803

December 23, 20178 counties in Maine; Franklin County, Middlesex County, Worcester County, Massachusetts; 9 counties in New Hampshire

The Storm Prediction Center issued this mesoscale discussion at Dec 23, 2017, 9:50 AM EST for 8 counties in Maine; Franklin County, Middlesex County, Worcester County, Massachusetts; 9 counties in New Hampshire. It was in force for 4 hr.

The area

The outline as issued.

The facts

Issued: Dec 23, 2017, 9:50 AM EST (14:50 UTC)
Expired: Dec 23, 2017, 1:45 PM EST
In force: 4 hr
Issued by: the Storm Prediction Center

Counties Franklin County, MA, Middlesex County, MA, Worcester County, MA, Androscoggin County, ME, Cumberland County, ME, Franklin County, ME, Kennebec County, ME, Oxford County, ME, Penobscot County, ME, Somerset County, ME, York County, ME, Belknap County, NH, Carroll County, NH, Cheshire County, NH, Grafton County, NH, Hillsborough County, NH, Merrimack County, NH, Rockingham County, NH, Strafford County, NH, Sullivan County, NH

The radar

The Portland,ME radar (KGYX), 28 km from the middle of the area, began a volume at 14:53 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

Albany, NY (KALY), launched 12:00Z, 2.8 hours before the alert went out and 302 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: 508 m above ground
0-6 km bulk shear: 57 kt
0-1 km storm-relative helicity: 222 m²/s²
0-3 km storm-relative helicity: 260 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

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SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Dec 23, 1:49 PM EST	Mesoscale Discussion	SPC	Androscoggin, Aroostook, Cumberland, Franklin, Kennebec, Oxford and 5 more	5 hr

Nearby

Mesoscale Discussions in New Hampshire, 2017 Mesoscale Discussions in Maine, 2017 Mesoscale Discussions in Massachusetts, 2017 Every mesoscale discussion in 2017

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.