Alert archive / North Carolina / Mesoscale Discussions in 2011

Mesoscale Discussion 795

May 16, 2011Dare County, North Carolina

The Storm Prediction Center issued this mesoscale discussion at May 16, 2011, 2:29 PM EDT for Dare County, North Carolina. It was in force for 91 min.

The area

The outline as issued.

The facts

Issued: May 16, 2011, 2:29 PM EDT (18:29 UTC)
Expired: May 16, 2011, 4:00 PM EDT
In force: 91 min
Issued by: the Storm Prediction Center

County Dare County, NC

The radar

The Morehead City radar (KMHX), 122 km from the middle of the area, began a volume at 18:30 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, 6.5 hours before the alert went out and 122 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: 2 J/kg
Mixed-layer CIN: -41 J/kg
Mixed-layer LCL: 1359 m above ground
0-6 km bulk shear: 30 kt
0-1 km storm-relative helicity: 55 m²/s²
0-3 km storm-relative helicity: 161 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

089 
ACUS11 KWNS 161829
SWOMCD
SPC MCD 161829 
NCZ000-162000-

MESOSCALE DISCUSSION 0795
NWS STORM PREDICTION CENTER NORMAN OK
0129 PM CDT MON MAY 16 2011

AREAS AFFECTED...NC OUTER BANKS

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

VALID 161829Z - 162000Z

A STRONG WIND GUST OR TWO...AND/OR A WATERSPOUT MOVING INLAND OVER
PRIMARILY THE OUTER BANKS OF NC ARE THREATS THIS AFTERNOON.  GIVEN
ISOLATED NATURE TO THIS THREAT AND LIMITED SPATIAL COVERAGE...A WW
IS NOT EXPECTED.

REGIONAL RADAR IMAGERY/LIGHTNING DATA SHOWED TSTMS EXTENDING FROM 55
S HSE TO 60 NE HSE...WITH THIS ACTIVITY LOCATED ALONG AN APPARENT
NNWWD MOVING CONVERGENCE ZONE.  THIS ACTIVITY APPEARS TO BE
ASSOCIATED WITH A WEAK MIDLEVEL IMPULSE TRACKING NNWWD TOWARD THE NC
OUTER BANKS PER TRENDS IN WATER VAPOR IMAGERY AND SHOULD CONTINUE TO
SUPPORT TSTM DEVELOPMENT MOVING NNWWD.  REGIONAL RADAR IMAGERY HAD
INDICATED PERSISTENT LOW LEVEL ROTATION WITH A STORM LOCATED 40 S
HSE AT 1815Z.  ALTHOUGH EFFECTIVE BULK SHEAR 30-35 KT SUPPORTS
MULTICELLS AND A LOW POTENTIAL FOR A SUPERCELL...WEAKER INSTABILITY
CLOSER TO THE COAST AND INLAND /MLCAPE AROUND 500 J/KG INVOF AND N-S
OF HSE/ SUGGESTS STORM INTENSITY MAY WEAKEN AS ACTIVITY REACHES THE
COAST.  

DESPITE THE WEAKER INSTABILITY...OBJECTIVE ANALYSES INDICATED
SURFACE VORTICITY ALONG THE CONVERGENCE ZONE AND SFC-3 KM CAPE OF
100-200 J/KG.  THIS MAY PROVE SUFFICIENT IN MAINTAINING AN ISOLATED
WATERSPOUT THREAT THROUGH THE AFTERNOON...WITH A BRIEF TORNADO
POSSIBLE...AS THE CONVERGENCE ZONE/TSTMS MOVE CLOSER TO THE COAST.

..PETERS.. 05/16/2011

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...MHX...

LAT...LON   34277635 35467589 36207556 36127483 35557458 34387539
            34127568 34277635

Nearby

Mesoscale Discussions in North Carolina, 2011 Every mesoscale discussion in 2011

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.