Alert archive / North Carolina / Mesoscale Discussions in 2018
Mesoscale Discussion 1721
The Storm Prediction Center issued this mesoscale discussion at Dec 20, 2018, 8:59 PM EST for 8 counties in North Carolina. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Dec 20, 2018, 8:59 PM EST (01:59 UTC)
- Expired
- Dec 20, 2018, 11:00 PM EST
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 20%
Counties Beaufort County, NC, Carteret County, NC, Craven County, NC, Dare County, NC, Hyde County, NC, Jones County, NC, Pamlico County, NC, Tyrrell County, NC
The radar
The Morehead City radar (KMHX), 28 km from the middle of the area, began a volume at 01:59 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 00:00Z, 2.0 hours before the alert went out and 28 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.
- Mixed-layer CAPE
- 178 J/kg
- Mixed-layer CIN
- -6 J/kg
- Mixed-layer LCL
- 653 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
- 280 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 1.1
The text
As transmitted.
815
ACUS11 KWNS 210159
SWOMCD
SPC MCD 210159
NCZ000-210400-
Mesoscale Discussion 1721
NWS Storm Prediction Center Norman OK
0759 PM CST Thu Dec 20 2018
Areas affected...Eastern North Carolina
Concerning...Severe potential...Watch unlikely
Valid 210159Z - 210400Z
Probability of Watch Issuance...20 percent
SUMMARY...Near surface stability should hinder the potential for
tornadoes even with relatively strong low-level wind fields in
place. A strong/severe wind gust will still be possible with the
strongest convective activity. A WW is not anticipated.
DISCUSSION...Over the past hour, trends in VWP hodographs from KLTX
have shown a decrease in low-level SRH. As the core of the 850 mb
low-level jet continues to move to the north/northeast, this trend
should continue. Though objective mesoanalysis shows effective SRH
values still in the 200-400 m2/s2 range, the 00Z MHX sounding shows
a stable layer near the surface that should limit the overall
potential for tornadoes. Furthermore, surface analysis has shown
dewpoints dropping over the last 2 hours near the coast. The main
threat with any ongoing convection will be limited to strong wind
gusts, given the remaining 35-50 kt flow in the lowest 2 km of the
troposphere. Trends will continue to be monitored, but a WW is not
anticipated.
..Wendt/Grams.. 12/21/2018
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...MHX...ILM...
LAT...LON 33557782 33847781 34427762 34937744 35477715 35997628
35977542 35367498 34257641 33687730 33447766 33557782SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Dec 21, 2:33 PM EST | Mesoscale Discussion | SPC | Alamance, Bladen, Caswell, Chatham, Columbus, Cumberland and 23 more | 57 min |
Nearby
Mesoscale Discussions in North Carolina, 2018Every 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.