Alert archive / Nebraska / Mesoscale Discussions in 2013

Mesoscale Discussion 1908

September 23, 201311 counties in Nebraska; Todd County, South Dakota

The Storm Prediction Center issued this mesoscale discussion at Sep 23, 2013, 1:58 PM MDT for 11 counties in Nebraska; Todd County, South Dakota. It was in force for 92 min.

The area

The outline as issued.

The facts

Issued: Sep 23, 2013, 1:58 PM MDT (19:58 UTC)
Expired: Sep 23, 2013, 3:30 PM MDT
In force: 92 min
Issued by: the Storm Prediction Center
Chance of a watch: 5%

Counties Arthur County, NE, Cherry County, NE, Frontier County, NE, Furnas County, NE, Gosper County, NE, Grant County, NE, Hooker County, NE, Keith County, NE, Lincoln County, NE, McPherson County, NE, Red Willow County, NE, Todd County, SD

The radar

The North Platte radar (KLNX), 40 km from the middle of the area, began a volume at 20:02 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

N. Platte/Lee Bi, NE (KLBF), launched 12:00Z, 8.0 hours before the alert went out and 52 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: 1617 m above ground
0-6 km bulk shear: 39 kt
0-1 km storm-relative helicity: 83 m²/s²
0-3 km storm-relative helicity: 162 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.

679 
ACUS11 KWNS 231959
SWOMCD
SPC MCD 231958 
NEZ000-SDZ000-232130-

MESOSCALE DISCUSSION 1908
NWS STORM PREDICTION CENTER NORMAN OK
0258 PM CDT MON SEP 23 2013

AREAS AFFECTED...WEST-CENTRAL/SOUTHWEST NEB TO FAR SOUTHERN SD

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

VALID 231958Z - 232130Z

PROBABILITY OF WATCH ISSUANCE...5 PERCENT

SUMMARY...A FEW FUNNEL CLOUDS AND POSSIBLY A BRIEF TORNADO MAY BE
POSSIBLE ASIDE FROM GUSTY WINDS ACROSS WEST-CENTRAL/SOUTHWEST NEB
AND PERHAPS FAR SOUTHERN SD THIS AFTERNOON.

DISCUSSION...PER WATER VAPOR IMAGERY/12Z UPPER AIR ANALYSIS...A
CLOSED/VERTICALLY STACKED CYCLONE CONTINUES TO MOVE
EAST-NORTHEASTWARD OVER THE WESTERN PORTIONS OF NEB/KS THIS
AFTERNOON...WITH A CORRESPONDING 996 MB SURFACE LOW LOCATED BETWEEN
HILL CITY KS/MCCOOK NEB AS OF 19Z. NORTH-NORTHWEST OF THE SURFACE
LOW...ISOLATED SEMI-DISCRETE TSTMS HAVE DEVELOPED AS FAR NORTH AS
THE NEB/SD BORDER WITHIN THE WARM/MODESTLY MOIST AIRMASS TO THE
IMMEDIATE EAST OF A NORTH-SOUTH ORIENTED EFFECTIVE FRONTAL ZONE.
ALTHOUGH DEEP LAYER/LOW-LEVEL SHEAR ARE WEAK IN THE IMMEDIATE
PROXIMITY OF THE STACKED CYCLONE...STEEP LOW-MID LEVEL LAPSE
RATES...UPPER 40S F SURFACE DEWPOINTS...AND AMBIENT VERTICAL
VORTICITY COULD ALLOW FOR A FEW FUNNELS/PERHAPS A SHORT-DURATION
TORNADO ACROSS SOUTHWEST/WEST-CENTRAL NEB AND PERHAPS SOUTHERN SD.

..GUYER/CORFIDI.. 09/23/2013

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

ATTN...WFO...GID...LBF...UNR...GLD...

LAT...LON   43410121 43110038 41400076 40880035 40639955 40049971
            40010034 41490208 43410121

Nearby

Mesoscale Discussions in Nebraska, 2013 Mesoscale Discussions in South Dakota, 2013 Every mesoscale discussion in 2013

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.