Alert archive / Iowa / Mesoscale Discussions in 2015

Mesoscale Discussion 2002

November 30, 201519 counties in Iowa; 13 counties in Nebraska

The Storm Prediction Center issued this mesoscale discussion at Nov 30, 2015, 6:44 AM CST for 19 counties in Iowa; 13 counties in Nebraska. It was in force for 5 hr.

The area

The outline as issued.

The facts

Issued: Nov 30, 2015, 6:44 AM CST (12:44 UTC)
Expired: Nov 30, 2015, 11:45 AM CST
In force: 5 hr
Issued by: the Storm Prediction Center

All 32 counties

Audubon County, IA, Buena Vista County, IA, Calhoun County, IA, Carroll County, IA, Cass County, IA, Cherokee County, IA, Clay County, IA, Crawford County, IA, Harrison County, IA, Ida County, IA, Mills County, IA, Monona County, IA, O'Brien County, IA, Plymouth County, IA, Pocahontas County, IA, Pottawattamie County, IA, Sac County, IA, Shelby County, IA, Woodbury County, IA, Burt County, NE, Cass County, NE, Dakota County, NE, Dodge County, NE, Douglas County, NE, Gage County, NE, Johnson County, NE, Lancaster County, NE, Otoe County, NE, Sarpy County, NE, Saunders County, NE, Thurston County, NE, Washington County, NE

The radar

The Omaha radar (KOAX), 47 km from the middle of the area, began a volume at 12:43 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

Omaha, NE (KOAX), launched 12:00Z, 0.7 hours before the alert went out and 47 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: 438 m above ground
0-6 km bulk shear: 62 kt
0-1 km storm-relative helicity: 95 m²/s²
0-3 km storm-relative helicity: 165 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.

493 
ACUS11 KWNS 301245
SWOMCD
SPC MCD 301244 
IAZ000-NEZ000-KSZ000-SDZ000-301745-

MESOSCALE DISCUSSION 2002
NWS STORM PREDICTION CENTER NORMAN OK
0644 AM CST MON NOV 30 2015

AREAS AFFECTED...PARTS OF NORTHEAST KANSAS...EASTERN NEBRASKA AND
WESTERN IOWA

CONCERNING...WINTER MIXED PRECIPITATION 

VALID 301244Z - 301745Z

SUMMARY...MUCH OF EASTERN NEB INTO NORTHWEST IA SHOULD HAVE MOSTLY
SNOW...WITH THIS OCCURRING GENERALLY WEST OF A LINE FROM GAGE COUNTY
NEB TO IN VICINITY OF KOMA...AND INTO NORTHWEST IA THROUGH KDNS TO
KEST.  SNOWFALL RATES SHOULD INCREASE TO AROUND 1 INCH PER HOUR THIS
MORNING.  LOCATIONS WITHIN THE EASTERN PORTION OF THE DISCUSSION
AREA...AND INCLUDING THE KOMA AREA...SHOULD HAVE AN INITIAL MIXTURE
OF PRECIP TYPES WITH FREEZING RAIN BEING PREDOMINANT AT RATES OF
0.05-0.10 INCHES PER 3 HOURS.  AROUND 15Z...MOST OF THESE LATTER
LOCATIONS SHOULD CHANGE TO RAIN IN THE SOUTH AND SNOW BECOMING THE
PRIMARY PRECIP TYPE WITH NORTHWARD EXTENT.

DISCUSSION...AN AREA OF PRECIPITATION WILL CONTINUE TO EXPAND
POLEWARD IN COVERAGE FROM NORTHEAST KS INTO EASTERN NEB AND WESTERN
IA THIS MORNING...WITH EMBEDDED TRANSIENT BANDS HAVING PERIODIC
HIGHER INTENSITIES.  TRENDS IN 1/ SATELLITE IMAGERY ACROSS EASTERN
NEB/WESTERN IA AND 2/ THE 00-12Z OBSERVED SOUNDINGS IN THE UPPER MS
VALLEY INDICATED ONGOING COLUMN SATURATION.  AN INCREASE IN UPWARD
VERTICAL MOTION IS EXPECTED ACROSS THE DISCUSSION AREA...GIVEN 1/
THE APPROACH OF A MIDLEVEL SHORTWAVE TROUGH MOVING ACROSS KS AND
EASTERN NEB THIS MORNING...AND 2/ THE EXIT REGION OF AN ACCOMPANYING
70-80 KT 500-MB JET SPREADING ACROSS THE MID MO VALLEY REGION.  AN
INCREASE IN LOW-LEVEL WARM ADVECTION SHOULD BE GREATEST ACROSS
IA...SUPPORTING FREEZING RAIN AS AN INITIAL PREDOMINANT
PRECIPITATION TYPE.  THE 12Z OMA SOUNDING SUPPORTED FREEZING RAIN
PER THE WARM NOSE CENTERED AROUND 800 MB.  MEANWHILE...FARTHER
WEST...A COOLING COLUMN ATTENDANT TO AN INCREASE IN UPWARD VERTICAL
MOTION SUGGESTS MUCH OF EASTERN NEB INTO NORTHWEST IA SHOULD HAVE
MAINLY SNOW.  09Z SREF GUIDANCE SUGGESTS SNOWFALL RATES OF 1 INCH
PER HOUR WILL BE POSSIBLE AS THE DEEP-LAYER ASCENT INCREASES FROM
SOUTH TO NORTH.

..PETERS.. 11/30/2015

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

ATTN...WFO...DMX...FSD...OAX...TOP...

LAT...LON   40719695 42209671 42589658 43139567 43059432 42449422
            41339489 41049537 39999643 39999692 40719695

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Nov 30, 12:03 PM CST	Mesoscale Discussion	SPC	Buena Vista, Cherokee, Clay, Dickinson, Emmet, Ida and 9 more	6 hr

Nearby

Mesoscale Discussions in Iowa, 2015 Mesoscale Discussions in Nebraska, 2015 Every mesoscale discussion in 2015

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.