Alert archive / North Carolina / Mesoscale Discussions in 2018

Mesoscale Discussion 3

January 3, 201822 counties in North Carolina; 5 counties in Virginia

The Storm Prediction Center issued this mesoscale discussion at Jan 3, 2018, 4:13 PM EST for 22 counties in North Carolina; 5 counties in Virginia. It was in force for 4 hr.

The area

The outline as issued.

The facts

Issued: Jan 3, 2018, 4:13 PM EST (21:13 UTC)
Expired: Jan 3, 2018, 8:15 PM EST
In force: 4 hr
Issued by: the Storm Prediction Center

All 27 counties

Beaufort County, NC, Bertie County, NC, Camden County, NC, Chowan County, NC, Currituck County, NC, Duplin County, NC, Edgecombe County, NC, Gates County, NC, Greene County, NC, Hertford County, NC, Jones County, NC, Lenoir County, NC, Martin County, NC, New Hanover County, NC, Onslow County, NC, Pasquotank County, NC, Pender County, NC, Perquimans County, NC, Pitt County, NC, Sampson County, NC, Washington County, NC, Wayne County, NC, City of Chesapeake, VA, City of Franklin, VA, City of Portsmouth, VA, City of Suffolk, VA, City of Virginia Beach, VA

The radar

The Morehead City radar (KMHX), 84 km from the middle of the area, began a volume at 21:16 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

Newport, NC (KMHX), launched 12:00Z, 9.2 hours before the alert went out and 83 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: 2260 m above ground
0-6 km bulk shear: 61 kt
0-1 km storm-relative helicity: 214 m²/s²
0-3 km storm-relative helicity: 318 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

353 
ACUS11 KWNS 032114
SWOMCD
SPC MCD 032113 
NCZ000-VAZ000-040115-

Mesoscale Discussion 0003
NWS Storm Prediction Center Norman OK
0313 PM CST Wed Jan 03 2018

Areas affected...Eastern NC...Southeast VA

Concerning...Winter mixed precipitation 

Valid 032113Z - 040115Z

SUMMARY...Heavy wintry mix will develop across eastern North
Carolina over the next few hours.  Heavy snow will develop later
this evening across northeast North Carolina into southeast
Virginia.

DISCUSSION...Surface low is deepening well off the FL coast and this
system will lift north-northeast during the evening hours remaining
east of the Outer Banks region through 12z. Latest radar data
suggests a secondary band of heavier precip is beginning to form off
the NC coast in response to large-scale forcing for ascent beginning
to maximize in this region. Over the next few hours there should be
a marked increase in precipitation over eastern NC, in line with
latest high-res model guidance and a heavy wintry mix is expected to
develop from near ILM to ECG. 18z sounding from MHX depicts a
substantial warm nose near 900mb and this layer will not cool
appreciably until after 02-03z. For this reason, freezing rain/ice
pellets can be expected in this zone through 04z. However,
precipitation should fall mostly as snow north of GSB to ECG. Snow
rates will increase through the evening hours with rates exceeding
1" and possibly approaching 2" per hour at times.

..Darrow.. 01/03/2018

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

ATTN...WFO...AKQ...MHX...RAH...ILM...

LAT...LON   34797867 36897682 36907573 36247586 35477684 34797733
            33867804 34797867

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jan 3, 11:09 AM EST	Mesoscale Discussion	SPC	Brunswick	4 hr

Nearby

Mesoscale Discussions in North Carolina, 2018 Mesoscale Discussions in Virginia, 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.