Alert archive / North Carolina / Mesoscale Discussions in 2017

Mesoscale Discussion 945

June 4, 201735 counties in North Carolina; 10 counties in Virginia

The Storm Prediction Center issued this mesoscale discussion at Jun 4, 2017, 3:15 PM EDT for 35 counties in North Carolina; 10 counties in Virginia. It was in force for 90 min.

The area

The outline as issued.

The facts

Issued: Jun 4, 2017, 3:15 PM EDT (19:15 UTC)
Expired: Jun 4, 2017, 4:45 PM EDT
In force: 90 min
Issued by: the Storm Prediction Center
Chance of a watch: 5%

All 45 counties

Alamance County, NC, Alexander County, NC, Alleghany County, NC, Anson County, NC, Cabarrus County, NC, Caswell County, NC, Catawba County, NC, Chatham County, NC, Cumberland County, NC, Davidson County, NC, Davie County, NC, Durham County, NC, Forsyth County, NC, Granville County, NC, Guilford County, NC, Harnett County, NC, Hoke County, NC, Iredell County, NC, Lee County, NC, Lincoln County, NC, Mecklenburg County, NC, Montgomery County, NC, Moore County, NC, Orange County, NC, Person County, NC, Randolph County, NC, Richmond County, NC, Rockingham County, NC, Rowan County, NC, Stanly County, NC, Stokes County, NC, Surry County, NC, Wake County, NC, Wilkes County, NC, Yadkin County, NC, Carroll County, VA, City of Danville, VA, City of Galax, VA, City of Martinsville, VA, Floyd County, VA, Franklin County, VA, Halifax County, VA, Henry County, VA, Patrick County, VA, Pittsylvania County, VA

The radar

The Roanoke radar (KFCX), 126 km from the middle of the area, began a volume at 19:18 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

Greensboro/Hi Pt, NC (KGSO), launched 12:00Z, 7.3 hours before the alert went out and 36 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: 1689 m above ground
0-6 km bulk shear: 20 kt
0-1 km storm-relative helicity: -16 m²/s²
0-3 km storm-relative helicity: 83 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

705 
ACUS11 KWNS 041915
SWOMCD
SPC MCD 041915 
NCZ000-VAZ000-042045-

Mesoscale Discussion 0945
NWS Storm Prediction Center Norman OK
0215 PM CDT Sun Jun 04 2017

Areas affected...Portions of North Carolina and far southern
Virginia

Concerning...Severe potential...Watch unlikely 

Valid 041915Z - 042045Z

Probability of Watch Issuance...5 percent

SUMMARY...A few strong to briefly severe storms may be capable of
gusty downburst winds producing localized damage this afternoon.
However, a watch does not appear warranted.

DISCUSSION...Clusters of thunderstorms have developed this
afternoon, aided by a weak impulse along the northern periphery of
mid-level ridging. Regional VWP data depict relatively weak flow
within the lower/middle troposphere, with winds generally 15-20 kt
or less. As such, overall storm organization should remain quite
limited. However, a very warm/moist boundary layer, combined with
some residual dry mid-level air (observed in 12Z GSO/RNK soundings),
is fostering an environment capable of occasional strong downburst
winds. Mesoanalysis data indicate a corridor of upwards of 1000 J/kg
of DCAPE ahead of a cluster of storms over central NC; therefore,
localized damaging gusts appear possible through early evening. This
threat will be further enhanced if merging storms can develop
organized trailing precipitation regions, although this seems
somewhat uncertain with stronger anvil-layer flow present.
Regardless, despite the threat for a few damaging gusts,
disorganized storm structures will preclude the need for a watch.

..Picca/Guyer.. 06/04/2017

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

ATTN...WFO...AKQ...RAH...ILM...RNK...GSP...

LAT...LON   35128085 35468137 35618141 35948138 36608115 36928077
            37098013 36947919 36537846 35507843 34897893 34888001
            35128085

Nearby

Mesoscale Discussions in North Carolina, 2017 Mesoscale Discussions in Virginia, 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.