Alert archive / Nebraska / Mesoscale Discussions in 2003

Mesoscale Discussion 403

April 6, 20034 counties in Kansas; 60 counties in Nebraska

The Storm Prediction Center issued this mesoscale discussion at Apr 6, 2003, 6:40 AM CDT for 4 counties in Kansas; 60 counties in Nebraska. It was in force for 5 hr.

The area

The outline as issued.

The facts

Issued: Apr 6, 2003, 6:40 AM CDT (11:40 UTC)
Expired: Apr 6, 2003, 11:45 AM CDT
In force: 5 hr
Issued by: the Storm Prediction Center

All 64 counties

Decatur County, KS, Norton County, KS, Phillips County, KS, Rawlins County, KS, Adams County, NE, Blaine County, NE, Boone County, NE, Buffalo County, NE, Butler County, NE, Cass County, NE, Chase County, NE, Clay County, NE, Colfax County, NE, Custer County, NE, Dawson County, NE, Dodge County, NE, Douglas County, NE, Fillmore County, NE, Franklin County, NE, Frontier County, NE, Furnas County, NE, Gage County, NE, Garfield County, NE, Gosper County, NE, Greeley County, NE, Hall County, NE, Hamilton County, NE, Harlan County, NE, Hayes County, NE, Hitchcock County, NE, Hooker County, NE, Howard County, NE, Jefferson County, NE, Johnson County, NE, Kearney County, NE, Keith County, NE, Lancaster County, NE, Lincoln County, NE, Logan County, NE, Loup County, NE, Madison County, NE, McPherson County, NE, Merrick County, NE, Nance County, NE, Nemaha County, NE, Nuckolls County, NE, Otoe County, NE, Pawnee County, NE, Perkins County, NE, Phelps County, NE, Platte County, NE, Polk County, NE, Red Willow County, NE, Saline County, NE, Sarpy County, NE, Saunders County, NE, Seward County, NE, Sherman County, NE, Thayer County, NE, Thomas County, NE, Valley County, NE, Webster County, NE, Wheeler County, NE, York County, NE

The radar

The Grand Island radar (KUEX), 86 km from the middle of the area, began a volume at 11:40 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 00:00Z, 11.7 hours before the alert went out and 139 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: 0 J/kg
Mixed-layer LCL: 480 m above ground
0-6 km bulk shear: 59 kt
0-1 km storm-relative helicity: 108 m²/s²
0-3 km storm-relative helicity: 321 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.

363 
ACUS11 KWNS 061141
SWOMCD
SPC MCD 061140 
IAZ000-MOZ000-NEZ000-KSZ000-061645-

MESOSCALE DISCUSSION 0403
NWS STORM PREDICTION CENTER NORMAN OK
0640 AM CDT SUN APR 06 2003

AREAS AFFECTED...NRN KS/S-CNTRL INTO ERN NEB

CONCERNING...HEAVY SNOW 

VALID 061140Z - 061645Z

HEAVY SNOW WITH RATES OF ONE INCH/HOUR ARE EXPECTED TO DEVELOP
EWD ACROSS THE AREA THROUGH 18Z.



CURRENT WATER VAPOR IMAGERY SHOWS INTENSE MID-/UPPER-LEVEL
SHORTWAVE TROUGH BEGINNING TO CLOSE OFF OVER NERN CO/SWRN NEB
WITH ASSOCIATED W-E DEFORMATION ZONE STRENGTHENING ACROSS NEB. IN
THE LOW LEVELS...30-40 KT LLJ AXIS EXTENDING FROM CNTRL OK INTO
S-CNTRL NEB CONTINUES TO TRANSPORT HIGHER MOISTURE CONTENT INTO
THE AREA ABOVE SUBFREEZING SURFACE TEMPERATURES.



DIFFERENTIAL ADVECTION OF LOW-LEVEL MOISTURE BENEATH STEEP
MID-LEVEL LAPSE RATES IN DRY SLOT ROTATING AROUND ERN QUADRANT OF
SHORTWAVE TROUGH HAS CONTRIBUTED TO CONVECTIVE DEVELOPMENT ACROSS
NRN KS/SRN NEB...PER REGIONAL RADAR/LIGHTNING DATA.



COMBINATION OF SATURATED...FAVORABLE TEMPERATURE PROFILE AND DEEP
LAYER FORCING FOR LARGE SCALE ASCENT ASSOCIATED WITH WAA ALONG
LLJ AND AGEOSTROPHIC RESPONSE TO MID-LEVEL FRONTOGENESIS WILL
SUPPORT A BAND OF HEAVY PRECIPITATION FROM NWRN/N-CNTRL KS INTO
SERN/E-CNTRL NEB THROUGH 18Z. 06Z ETA POINT FORECAST SOUNDINGS
AND PLAN VIEW PRECIPITATION TYPE ALGORITHM OUTPUT SUGGEST A
NARROW SWATH OF FREEZING RAIN AND/OR SLEET FROM NWRN KS /GLD AND
HLC AREAS/ NEWD THROUGH HSI/GRI TO AROUND BIE BY EARLY AFTERNOON.
TO THE N OF THIS AREA...HEAVY SNOW /I.E. RATES OF ONE INCH/HOUR
OR GREATER/ IS EXPECTED TO EXPAND EWD FROM SWRN NEB EWD ACROSS
S-CNTRL/CNTRL NEB INTO ERN NEB...PRIMARILY S OF AN OMA TO OLU
LINE. ONGOING CONVECTION WILL LOCALLY ENHANCE PRECIPITATION
RATES.	  

..MEAD.. 04/06/2003

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

ATTN...WFO...EAX...OAX...TOP...GID...LBF...GLD...

40640198 41400161 42030108 42180005 42169863 41979755
41699657 41329592 40509567 40009603 39839766 39779922
39770136

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Apr 6, 5:41 PM CDT	Mesoscale Discussion	SPC	Burt, Cedar, Cuming, Dakota, Dixon, Pierce and 3 more	5 hr

Nearby

Mesoscale Discussions in Nebraska, 2003 Mesoscale Discussions in Kansas, 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; radar from the NEXRAD Level II archive.