Alert archive / Nebraska / Mesoscale Discussions in 2007

Mesoscale Discussion 920

May 29, 20075 counties in Colorado; 7 counties in Kansas; 16 counties in Nebraska

The Storm Prediction Center issued this mesoscale discussion at May 29, 2007, 4:34 PM MDT for 5 counties in Colorado; 7 counties in Kansas; 16 counties in Nebraska. It was in force for 3 hr.

The area

The outline as issued.

The facts

Issued: May 29, 2007, 4:34 PM MDT (22:34 UTC)
Expired: May 29, 2007, 7:30 PM MDT
In force: 3 hr
Issued by: the Storm Prediction Center

All 28 counties

Cheyenne County, CO, El Paso County, CO, Kit Carson County, CO, Lincoln County, CO, Yuma County, CO, Cheyenne County, KS, Decatur County, KS, Norton County, KS, Rawlins County, KS, Sherman County, KS, Thomas County, KS, Wallace County, KS, Buffalo County, NE, Chase County, NE, Dawson County, NE, Dundy County, NE, Frontier County, NE, Furnas County, NE, Gosper County, NE, Harlan County, NE, Hayes County, NE, Hitchcock County, NE, Kearney County, NE, Lincoln County, NE, Perkins County, NE, Phelps County, NE, Red Willow County, NE, Sherman County, NE

The radar

The Goodland radar (KGLD), 58 km from the middle of the area, began a volume at 22:37 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 watches that followed

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

The nearest sounding before it

Denver, CO (KDNR), launched 12:00Z, 10.6 hours before the alert went out and 119 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: 18 J/kg
Mixed-layer CIN: -196 J/kg
Mixed-layer LCL: 1497 m above ground
0-6 km bulk shear: 33 kt
0-1 km storm-relative helicity: -86 m²/s²
0-3 km storm-relative helicity: -23 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.2

Open this sounding in Storm Lab

The text

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

000 
ACUS11 KWNS 292234
SWOMCD
SPC MCD 292234 
NEZ000-KSZ000-COZ000-300130-

MESOSCALE DISCUSSION 0920
NWS STORM PREDICTION CENTER NORMAN OK
0534 PM CDT TUE MAY 29 2007

AREAS AFFECTED...PORTIONS E-CENTRAL/NERN CO...NWRN
KS...SWRN/S-CENTRAL NEB.

CONCERNING...HEAVY RAINFALL 

VALID 292234Z - 300130Z

ORGANIZED/MESOSCALE HEAVY RAIN EVENT WILL TAKE PLACE THROUGH AT
LEAST 2Z ACROSS SWATH FROM GRI AREA WSWWD ACROSS NWRN KS AND
E-CENTRAL CO...S THROUGH E OF LIC.  RATES 2 INCHES/HOUR WILL BE
COMMON...WITH RATES 3-5 INCHES/HOUR LOCALLY OCCURRING IN HP
SUPERCELLS AND MERGING STORMS.  2.5 INCHES IN HALF AN HOUR ALREADY
HAS BEEN MEASURED AT SFC WITH DISCRETE/SLOW MOVING TSTM OVER NRN
YUMA COUNTY CO...AND SIMILAR/VERY LOCALIZED EVENTS WILL REMAIN
POSSIBLE WITHIN LARGER HEAVY PRECIP AREA AS IT CONSOLIDATES
EWD/ESEWD ACROSS DISCUSSION AREA.

AS OF 2215Z...LINE OF TSTMS IS BECOMING BETTER ORGANIZED FROM KEITH
COUNTY NEB SWWD ACROSS LIC/COS AREAS...AND WILL MOVE EWD INTO
FAVORABLE MOISTURE AND 30-40 KT STORM-RELATIVE INFLOW ACROSS SWRN
NEB/NERN CO AND INTO NWRN KS.  MEANWHILE...OUTFLOW BOUNDARY FROM
ONGOING CONVECTION OVER SRN NEB IS ANALYZED NEAR
GRI...HDE...MCK...30 SW IML LINE...AND MAY DRIFT SWD IN SOME AREAS. 
20-25 KT SELY FLOW AT 850 MB WILL CONTINUE TO TRANSPORT FAVORABLY
MOIST LOW LEVEL AIR MASS ATOP THIS BOUNDARY FOR CONTINUED RISK OF
HEAVY RAINFALL ALONG BOUNDARY AND TO ITS N.
EXPECT WESTERN CONVECTIVE BAND TO OVERTAKE AND MERGE WITH CONVECTION
N OF OUTFLOW BOUNDARY...MAXIMIZING ADDITIONAL LIFT AND EXACERBATING
HEAVY RAIN THREAT.  GPS DATA...MODIFIED RAOBS AND RUC GUIDANCE
SUGGEST AROUND 1.25 INCH PW IN PROSPECTIVE INFLOW AIR MASS OVER MOST
OF REGION...EXPECIALLY FROM EXTREME ERN CO EWD ACROSS KS/NEB BORDER
AREA.  1500-2500 J/KG MUCAPE...STRONG STORM-RELATIVE INFLOW AND
FAVORABLE PROPAGATIONAL VECTORS WILL HELP TO MAINTAIN EFFICIENT
PRECIP PRODUCTION.

FOR SVR THREAT REF WW 304 AND RELATED MESOSCALE DISCUSSIONS.

..EDWARDS.. 05/29/2007

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

ATTN...WFO...GID...LBF...GLD...PUB...BOU...

38890473 39220365 39760299 40400239 41170167 41340024
41429882 40849861 39989921 39310074 38670221 38530380

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 29, 12:12 PM MDT	Mesoscale Discussion	SPC	Adams, Arapahoe, Bent, Broomfield, Cheyenne, Crowley and 16 more	93 min
May 29, 12:29 PM MDT	Tornado Watch	SPC	Adams, Arapahoe, Denver, Douglas, Elbert, El Paso and 9 more	8 hr
May 29, 2:52 PM MDT	Mesoscale Discussion	SPC	Adams, Arapahoe, Bent, Broomfield, Cheyenne, Crowley and 16 more	53 min
May 29, 5:08 PM MDT	Tornado Watch	SPC	Baca, Bent, Cheyenne, Crowley, Huerfano, Kiowa and 4 more	4 hr
May 29, 5:40 PM MDT	Mesoscale Discussion	SPC	Baca, Bent, Cheyenne, Crowley, Huerfano, Kiowa and 7 more	95 min
May 28, 8:03 PM MDT	Mesoscale Discussion	SPC	Hayes	87 min

Nearby

Mesoscale Discussions in Nebraska, 2007 Mesoscale Discussions in Kansas, 2007 Mesoscale Discussions in Colorado, 2007 Every mesoscale discussion in 2007

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.