Alert archive / South Dakota / Mesoscale Discussions in 2003

Mesoscale Discussion 1049

May 17, 20034 counties in Nebraska; 14 counties in South Dakota; Goshen County, Niobrara County, Platte County, Wyoming

The Storm Prediction Center issued this mesoscale discussion at May 17, 2003, 2:23 PM MDT for 4 counties in Nebraska; 14 counties in South Dakota; Goshen County, Niobrara County, Platte County, Wyoming. It was in force for 3 hr.

The area

The outline as issued.

The facts

Issued: May 17, 2003, 2:23 PM MDT (20:23 UTC)
Expired: May 17, 2003, 5:00 PM MDT
In force: 3 hr
Issued by: the Storm Prediction Center

All 21 counties

Box Butte County, NE, Dawes County, NE, Sheridan County, NE, Sioux County, NE, Bennett County, SD, Custer County, SD, Dewey County, SD, Fall River County, SD, Haakon County, SD, Jackson County, SD, Jones County, SD, Meade County, SD, Oglala Lakota County, SD, Pennington County, SD, Potter County, SD, Stanley County, SD, Sully County, SD, Ziebach County, SD, Goshen County, WY, Niobrara County, WY, Platte County, WY

The watches that followed

Watches SPC issued over any of the same counties within four hours of this discussion.

Severe Thunderstorm Watch 409May 17, 2:55 PM MDT

The nearest sounding before it

Rapid City, SD (KUNR), launched 12:00Z, 8.4 hours before the alert went out and 66 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: 657 m above ground
0-6 km bulk shear: 46 kt
0-1 km storm-relative helicity: 60 m²/s²
0-3 km storm-relative helicity: 248 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.

002 
ACUS11 KWNS 172023
SWOMCD
SPC MCD 172023 
SDZ000-NEZ000-WYZ000-172300-

MESOSCALE DISCUSSION 1049
NWS STORM PREDICTION CENTER NORMAN OK
0323 PM CDT SAT MAY 17 2003

AREAS AFFECTED...ERN WY...NWRN NEB...WRN SD

CONCERNING...SEVERE THUNDERSTORM POTENTIAL 

VALID 172023Z - 172300Z

INCREASINGLY FAVORABLE ENVIRONMENTAL CONDITIONS WERE DEVELOPING FOR
A FEW SEVERE TSTMS ACROSS THE CNTRL HIGH PLAINS LATE THIS AFTERNOON
AND INTO THIS EVENING. A WEATHER WATCH MAY BE NEEDED OVER PARTS OF
EXTREME ERN WY INTO WRN NEB/SD IN THE NEXT 1-2 HOURS.

LOW LEVEL UPSLOPE FLOW OCCURRING BENEATH BROADLY DIFFLUENT UPPER
FLOW ALONG SRN EDGE OF MID LEVEL JET WILL CONTINUE TO PROMOTE LARGE
SCALE ASCENT AND DESTABILIZATION OVER ERN WY EWD OVER WRN NEB/SD.
BOUNDARY LAYER MOISTURE FOCUSED ALONG FRONT/LEE LOW INTERSECTION
NEAR SERN WY COUPLED WITH STRONG INSOLATION WAS CONTRIBUTING TO
WEAKLY CAPPED MLCAPE OF 250-750 J/KG BASED ON LATEST RUC FORECAST
SOUNDINGS ADJUSTED FOR OBSERVED SFC CONDITIONS. THIS INSTABILITY
SHOULD BE SUFFICIENT TO MAINTAIN RELATIVELY HIGH-BASED UPDRAFTS FROM
THE LEE LOW ENEWD ALONG AND NORTH OF THE SURFACE FRONT SITUATED FROM
THE NEB PANHANDLE INTO SWRN/S-CNTRL SD. STRONG DIRECTIONAL SHEAR ON
THE FRONT...AND DEEP LAYER SPEED SHEAR...WILL PROMOTE STORM ROTATION
WITH A FEW SUPERCELLS POSSIBLY PRODUCING HAIL AND/OR STRONG WINDS.
WHILE GREATEST CHANCE FOR INITIATION IN THE SHORT-TERM APPEARS TO BE
OVER SERN WY...EXPECT THE BOUNDARY WILL ALSO BE A FOCUS FOR STORM
INITIATION AS STRENGTHENING LOW LEVEL INFLOW DEVELOPS LATER EVENING.

..CARBIN.. 05/17/2003

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

ATTN...WFO...ABR...LBF...UNR...CYS...

43110142 42400249 41360503 42580498 43740449 45580149
45740091 45299987 44429997

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 17, 2:55 PM MDT	Severe Thunderstorm Watch	SPC	Banner, Box Butte, Cherry, Dawes, Morrill, Scotts Bluff and 2 more	6 hr
May 17, 5:45 PM MDT	Mesoscale Discussion	SPC	Box Butte, Cherry, Dawes, Sheridan, Sioux	2 hr

Nearby

Mesoscale Discussions in South Dakota, 2003 Mesoscale Discussions in Nebraska, 2003 Mesoscale Discussions in Wyoming, 2003 Every mesoscale discussion in 2003

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.