Alert archive / North Carolina / Mesoscale Discussions in 2021
Mesoscale Discussion 399
The Storm Prediction Center issued this mesoscale discussion at Apr 19, 2021, 10:15 AM EDT for 15 counties in North Carolina. It was in force for 3 hr.
The area
The outline as issued.
The facts
- Issued
- Apr 19, 2021, 10:15 AM EDT (14:15 UTC)
- Expired
- Apr 19, 2021, 12:45 PM EDT
- In force
- 3 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch unlikely
- Chance of a watch
- 20%
Counties Beaufort County, NC, Camden County, NC, Carteret County, NC, Chowan County, NC, Craven County, NC, Currituck County, NC, Dare County, NC, Hyde County, NC, Jones County, NC, Onslow County, NC, Pamlico County, NC, Pasquotank County, NC, Perquimans County, NC, Tyrrell County, NC, Washington County, NC
The radar
The Morehead City radar (KMHX), 104 km from the middle of the area, began a volume at 14:15 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, 2.3 hours before the alert went out and 103 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
- 41 J/kg
- Mixed-layer CIN
- -78 J/kg
- Mixed-layer LCL
- 1087 m above ground
- 0-6 km bulk shear
- 76 kt
- 0-1 km storm-relative helicity
- 32 m²/s²
- 0-3 km storm-relative helicity
- 96 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
953
ACUS11 KWNS 191415
SWOMCD
SPC MCD 191415
NCZ000-191645-
Mesoscale Discussion 0399
NWS Storm Prediction Center Norman OK
0915 AM CDT Mon Apr 19 2021
Areas affected...Northeastern NC
Concerning...Severe potential...Watch unlikely
Valid 191415Z - 191645Z
Probability of Watch Issuance...20 percent
SUMMARY...A few stronger storms are possible across northeast North
Carolina over the next several hours.
DISCUSSION...Recent surface analysis places a low over far southeast
SC with a trough extending northward across eastern NC to another
low near the far eastern NC/VA border. This trough is demarcated
well by the wind shift across eastern NC. Dewpoints to the east of
this trough are mainly in the upper 50s and low 60s, with
temperatures in the mid to upper 60s. These low-level thermodynamic
conditions sit beneath similarly modest thermodynamic conditions
aloft, with 500-mb temperatures around -19 deg C and poor lapse
rates. As such, overall thermodynamic conditions support only modest
buoyancy.
Even so, strengthening ascent, resulting from low-level convergence
along the trough as well as the approach of a mid-level trough and
attendant jet, coupled with the modest buoyancy is expected to
foster storm development. The strength of the vertical shear could
result in stronger storms than the modest buoyancy would otherwise
suggest, with isolated hail and/or damaging wind gusts possible.
Overall coverage of any strong storms should be limited, with the
duration of any such storms also tempered given the lack of stronger
buoyancy.
..Mosier/Guyer.. 04/19/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...AKQ...MHX...
LAT...LON 35957699 36497649 36357576 35897545 35177556 34577663
34807786 35957699Nearby
Mesoscale Discussions in North Carolina, 2021Every mesoscale discussion in 2021
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.