Alert archive / Nebraska / Mesoscale Discussions in 2011

Mesoscale Discussion 428

April 14, 2011Phillips County, Sedgwick County, Colorado; 14 counties in Nebraska; Mellette County, Todd County, Tripp County, South Dakota

The Storm Prediction Center issued this mesoscale discussion at Apr 14, 2011, 5:19 PM MDT for Phillips County, Sedgwick County, Colorado; 14 counties in Nebraska; Mellette County, Todd County, Tripp County, South Dakota. It was in force for 4 hr.

The area

The outline as issued.

The facts

Issued
Apr 14, 2011, 5:19 PM MDT (23:19 UTC)
Expired
Apr 14, 2011, 9:15 PM MDT
In force
4 hr
Issued by
the Storm Prediction Center

Counties Phillips County, CO, Sedgwick County, CO, Arthur County, NE, Chase County, NE, Cherry County, NE, Deuel County, NE, Dundy County, NE, Garden County, NE, Grant County, NE, Hayes County, NE, Hooker County, NE, Keith County, NE, McPherson County, NE, Perkins County, NE, Sheridan County, NE, Thomas County, NE, Mellette County, SD, Todd County, SD, Tripp County, SD

The radar

The North Platte radar (KLNX), 83 km from the middle of the area, began a volume at 23:21 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, 11.3 hours before the alert went out and 100 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-pSkew-T log-p diagram, N. Platte/Lee Bi, NE at 12:00Z on 2011-04-14Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1 joules per kilogram.LCLEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, N. Platte/Lee Bi, NE at 12:00Z on 2011-04-14The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 178 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
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
1 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
541 m above ground
0-6 km bulk shear
27 kt
0-1 km storm-relative helicity
178 m²/s²
0-3 km storm-relative helicity
206 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.

444 
ACUS11 KWNS 142320
SWOMCD
SPC MCD 142319
SDZ000-NEZ000-COZ000-150315-

MESOSCALE DISCUSSION 0428
NWS STORM PREDICTION CENTER NORMAN OK
0619 PM CDT THU APR 14 2011

AREAS AFFECTED...S-CNTRL SD / WRN NEB / FAR NERN CO

CONCERNING...HEAVY SNOW

VALID 142319Z - 150315Z

SNOWFALL RATES OF 1 TO 2 INCHES PER HOUR ARE ANTICIPATED ACROSS
PORTIONS OF S-CNTRL SD...WRN NEB...AND FAR NERN CO THIS EVENING.

COMPACT DEEP-LAYER LOW PRESSURE CENTERED OVER WRN/CNTRL KS IS
ASSOCIATED WITH A PLUME OF DEEP MOIST ASCENT PIVOTING INTO THE NWRN
SEMICIRCLE OF THE CIRCULATION. IN THIS REGION...COLD AIR THROUGHOUT
THE TROPOSPHERE CONTINUES TO PLUNGE SWD...WITH SNOW ONGOING ACROSS
PORTIONS OF WRN NEB AND NERN CO. WHILE THE SFC LOW IS FORECAST TO
ONLY SLOWLY TRACK EWD TO E-SEWD DURING INTO THIS EVENING...LATEST
RUC GUIDANCE SUGGESTS THAT STRONG 850-700-MB FRONTOGENESIS WILL
SHIFT N-NEWD IN RESPONSE TO THE STRONGLY SUBSIDENT DRY CONVEYOR BELT
WRAPPING INTO THE NRN SEMICIRCLE OF THE LOW. IN TURN...THE HEAVIER
PRECIP WILL SHIFT N-NEWD INTO THE EVENING...WITH THE STRONG
FRONTOGENESIS AND DEEP-LAYER ASCENT SUPPORTING SNOWFALL RATES OF 1
TO 2 INCHES PER HOUR /HIGHEST NEAR ANY LIGHTNING-PRODUCING
CONVECTION/. WHILE THE LOWER TROPOSPHERIC PROFILE WILL INITIALLY BE
CONDUCIVE FOR RAIN ACROSS PORTIONS OF CNTRL NEB/SD...RUC FORECAST
SOUNDINGS SUGGEST THAT LOW-LEVEL COLD AIR ADVECTION WILL SUPPORT A
CHANGEOVER TO SNOW AFTER 03Z. THE SNOW WILL LIKELY PERSIST THROUGH
THE OVERNIGHT HOURS WHILE GRADUALLY SHIFTING EWD...WITH SNOW LIKELY
SHIFTING EWD OUT OF NERN CO AFTER 06Z PER EXPERIMENTAL HRRR
GUIDANCE.

..COHEN.. 04/14/2011

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

ATTN...WFO...FSD...ABR...LBF...UNR...GLD...BOU...CYS...

LAT...LON   40350273 41890280 42780223 43960050 43479947 41970041
            40610092 40050187 40350273

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 14, 5:18 PM MDTMesoscale DiscussionSPCNuckolls, Thayer, Webster117 min

Nearby

Mesoscale Discussions in Nebraska, 2011Mesoscale Discussions in South Dakota, 2011Mesoscale Discussions in Colorado, 2011Every 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.